Skip Navigation



Briefings in Functional Genomics Advance Access published online on January 11, 2008
Briefings in Functional Genomics, doi:10.1093/bfgp/elm030
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
6/4/322    most recent
elm030v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Cerda, B. D. l.
Right arrow Articles by Rosa, M. A. D. l.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Cerda, B. D. l.
Right arrow Articles by Rosa, M. A. D. l.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© Oxford University Press, 2008, All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org

A proteomic approach to iron and copper homeostasis in cyanobacteria

Berta De la Cerda, Ornella Castielli, Raúl V. Durán, José A. Navarro, Manuel Hervás and Miguel A. De la Rosa

Corresponding author. Miguel A. De la Rosa, Instituto de Bioquímica Vegetal y Fotosíntesis, Avda. Américo Vespucio 49, 41092 Sevilla, Spain. Tel: +34-954-489-506; Fax: +34-954-460-065; E-mail: marosa{at}us.es


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 IRON-COPPER HOMEOSTASIS IN...
 SYNECHOCYSTIS PROTEOMIC STUDIES
 petE AND petJ KNOCKOUT...
 Acknowledgements
 References
 
Cyanobacteria, which are considered to be the chloroplast precursors, are significant contributors to global photosynthetic productivity. The ample variety of membrane and soluble proteins containing different metals (mainly, iron and copper) has made these organisms develop a complex homeostasis with different mechanisms and tight regulation processes to fulfil their metal requirements in a changing environment. Cell metabolism is so adapted as to synthesize alternative proteins depending on the relative metal availabilities. In particular, plastocyanin, a copper protein, and cytochrome c6, a haem protein, can replace each other to play the same physiological role as electron carriers in photosynthesis and respiration, with the synthesis of one protein or another being regulated by copper concentration in the medium. The unicellular cyanobacterium Synechocystis sp. PCC 6803 has been widely used as a model system because of completion of its genome sequence and the ease of its genetic manipulation, with a lot of proteomic work being done. In this review article, we focus on the functional characterization of knockout Synechocystis mutants for plastocyanin and cytochrome c6, and discuss the ongoing proteomic analyses performed at varying copper concentrations to investigate the cyanobacterial metal homeostasis and cell response to changing environmental conditions.

Keywords: proteomic, cyanobacteria, copper homeostasis, iron homeostasis, Synechocystis


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
IRON-COPPER HOMEOSTASIS IN...
 SYNECHOCYSTIS PROTEOMIC STUDIES
 petE AND petJ KNOCKOUT...
 Acknowledgements
 References
 
Trace metals have an important role in cell metabolism by acting as redox co-factors in enzymes involved in multiple metabolic pathways [1]. In particular, iron and copper participate in essential metabolic routes, namely photosynthesis and respiration. However, at high concentrations both metals promote the generation of reactive oxygen species (ROS) and, subsequently, oxidative damage and impaired cell function and death, which are processes involved in several pathologies and neurodegenerative diseases [2, 3]. Micronutrient (especially iron) acquisition and sequestration can be crucial for competing organisms in invading particular niches or in infecting cells in a host–pathogen interaction. Thus, the importance of metal homeostasis in maintaining intracellular bioavailability of essential metal ions within a range compatible with cell viability becomes evident. Homeostatic mechanisms comprise metal sensing, chelation and transport [4, 5].

The functioning of oxygenic photosynthesis requires several membrane complexes and soluble proteins containing either iron (including iron–sulphur clusters and haem groups) or copper as co-factors [6]. Actually, the requirement for iron and copper of photosynthetic organisms exceeds that of non-photosynthetic ones. This results in higher metal demand and in increased sensitivity to metal limitation, along with the production of ROS during photosynthetic activity [7].

Cyanobacteria, prokaryotic organisms performing oxygenic photosynthesis, are significant contributors to the global photosynthetic productivity [8]. They grow in a wide variety of marine and terrestrial environments, in which metal deficiencies can frequently occur, thereby leading to different adaptative responses to overcome metal limitations [7, 8].

In particular, the unicellular cyanobacterium Synechocystis sp. PCC 6803 (hereinafter referred to as Synechocystis) is a widely used model system to study photosynthesis and other metabolic processes. It is the first photosynthetic organism for which the complete genome sequence was determined [9]; it is suitable to be genetically manipulated, so becoming transformable by exogenous DNA upon homologous recombination and integration; and its metabolic versatility allows it not only to survive in a wide variety of environments—including those with different metal limitations—but also to live under non-photosynthetic conditions if a suitable carbon source, such as glucose, is available. All these features make Synechocystis the subject for research in many studies. In fact, several deletion mutants lacking specific genes have been analysed [10, 11], and a number of proteomic studies under different environmental conditions and stresses have been carried out [12].

In this article, we focus on the functional characterization of Synechocystis knockout mutants for plastocyanin (Pc) and cytochrome c6 (Cyt), the two alternative soluble proteins involved in electron transport both in photosynthesis and respiration. We also discuss the comparative proteomic analysis of the native strain and the deletion mutants grown with or without copper, thus yielding relevant information on the metal homeostasis in cyanobacteria and the response of these organisms to changing environmental conditions.


   IRON–COPPER HOMEOSTASIS IN CYANOBACTERIA
TOP
 ABSTRACT
 INTRODUCTION
 IRON-COPPER HOMEOSTASIS IN...
SYNECHOCYSTIS PROTEOMIC STUDIES
 petE AND petJ KNOCKOUT...
 Acknowledgements
 References
 
Life on our planet started up in a reductive environment, but after the development of oxygenic photosynthesis, oxygen enrichment modified the composition of the atmosphere. This event changed the bio-availability of trace mineral elements and made iron a limiting nutrient because soluble ferrous ions were oxidized to the insoluble ferric species as the prevalent form of iron in the biosphere. Simultaneously, copper changed from highly insoluble sulphides to soluble cupric salts [13]. Iron biochemistry persistence was due to the further development of Fe(III) chelators, which rendered iron once again available, and prevented potential iron toxicity by its storage in ferritin. Whereas enzymes involved in anaerobic metabolism function at low redox potential, the biochemistry of copper can take advantage of the oxidizing power of oxygen to perform reactions at higher redox potentials [13]. Furthermore, there are a number of similar reactions catalysed by analogue enzymes containing either copper or iron (Table 1).


View this table:
[in this window]
[in a new window]

  		Table 1: Equivalent physiological roles played by copper and iron proteins

 
In some cases, metabolic adaptation allows the organisms to use one catalyst over the other depending on metal availability [14]. In particular, many algae and cyanobacteria synthesize the soluble electron carrier Pc or Cyt depending on copper availability, thus suggesting that these organisms can experience copper-deficiency in nature [15, 16]. Similarly, iron limitation induces the expression of new proteins, namely chlorophyll-binding proteins, and the replacement of the iron-containing protein ferredoxin by the flavin-containing protein flavodoxin to transfer electrons from photosystem I (PSI) to ferredoxin-NADP+ reductase [6]. Regulation of these switches involves different mechanisms (apoprotein degradation, transcriptional regulation) depending on the organism. For instance, the amount of mRNA for the Pc-encoding petE and Cyt-encoding petJ genes seem to be regulated by copper at the level of the initiation of transcription in Synechocystis and other cyanobacteria [17, 18]. Actually, Pc-mRNA is detected only in the presence of copper and Cyt-mRNA is detected only in the absence of copper [18].

Cyanobacteria contain internal compartments called thylakoids, which are distinct from the periplasm. Thylakoids are the site for both photosynthetic and respiratory electron transports, involving the copper proteins Pc and cytochrome c oxidase, the latter containing a binuclear copper centre oriented towards the thylakoidal lumen. Pc is imported inside the thylakoid via the typical prokaryotic Sec (for secretion) pathway for unfolded proteins [5]. Cyanobacterial thylakoids are currently the only location for copper enzymes known to require this metal entering into the bacterial cytoplasm. Consequently, copper is transported across the plasma and thylakoidal membranes by the consecutive action of two different P-type ATPases, the so-called CtaA and PacS complexes (Figure 1) [7]. Inside the cell, copper is chaperoned by Atx1, a small soluble protein that contains the typical copper-binding motif CXXC [7]. Atx1 is presumed to acquire copper from CtaA and donate it to PacS (Figure 1), although only the latter process has been demonstrated to occur [5]. Atx1 can also function, to a certain extent, in the absence of CtaA, indicating that it may acquire copper from another unknown importer [5]. Basically, a similar copper transport mechanism has been conserved in higher plants [7].


Figure 1
View larger version (34K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Figure 1: Pathways for copper and iron intake in Synechocystis cells and proteins requiring them to play their role in photosynthesis and respiration. FutA1, A2, B and C are the components of the FutABC ferric iron transporter; FeoB is responsible for ferrous iron transport; CtaA and PacS are two P-type ATPases for copper transport to the cytoplasm and thylakoidal lumen, respectively. Bacterioferritin (Bfr) is the iron-storing molecule, and the anti-oxidant protein 1 (Atx1) is a metallochaperone that functions by delivering copper to PacS. The abbreviations for the photosynthetic and respiratory components are as follows: PSI and PSII, photosystem I and II; PQ, plastoquinone; b6f, cytochrome b6f complex; Pc, plastocyanin; Cyt, cytochrome c6; Fd, ferredoxin; Fld, flavodoxin; NDH, NADH dehydrogenase; COX, cytochrome c oxidase. The scheme has been adapted from [7, 19, 20].

 
In Synechocystis, the iron ATP-binding cassette (ABC) transporter FutABC has been identified as a major contributor to ferric iron transport across the plasma membrane (Figure 1) [19]. This transporter is composed of four polypeptides: FutA1 and FutA2, localized in the periplasm, and FutB and FutC, probably forming an inner-membrane bound unit [19]. On the other hand, ferrous iron uptake depends on the FeoB iron transporter, although it is not essential for iron acquisition unless the ferric pathway is disabled [19]. In plants, it is not yet known whether a similar ABC transporter is involved in iron uptake [7]. Once inside the cyanobacterial cell, up to 50% of the stored Fe(II) is associated to bacterioferritin, where it is oxidized to the insoluble Fe(III) form before being transferred to the different protein substrates [7].


   SYNECHOCYSTIS PROTEOMIC STUDIES
TOP
 ABSTRACT
 INTRODUCTION
 IRON-COPPER HOMEOSTASIS IN...
 SYNECHOCYSTIS PROTEOMIC STUDIES
petE AND petJ KNOCKOUT...
 Acknowledgements
 References
 
After genome sequencing, Synechocystis soon became an excellent candidate for an in-depth proteomic analysis. In the classical proteomic approach, proteins are first separated in one dimension according to their isoelectric point by isoelectric focusing, and after in the second dimension by standard SDS-PAGE. The resulting spots are stained and excised from the gel, digested by trypsin and subjected to mass spectrometry (MS) for protein identification by comparing the data obtained with the theoretical trypsin digestion products in databases [20]. The first proteomic studies [21, 22] did allow the construction of a linkage map between 2D-gels and gene expression, with the spot identification being based on micro-sequencing rather than on MS methods. Up to 234 proteins were identified in Synechocystis and were placed in the Cyano2Dbase as a source for future studies [9].

Subcellular fractionation can also be performed to further increase the number of proteins identified. In this way, separate data can be attained for the subproteomes of soluble and periplasmic fractions, for the plasma membrane, for the outer and thylakoidal membranes and even for the peripheral proteins associated with the latter membrane [23–28]. However, more interesting than revealing the whole catalogue of proteins that constitute the proteome of a given organism is the comparison of quantitative protein profiles when the cells are subjected to varying environmental conditions, thus allowing the identification of differentially expressed proteins. This is a much simpler way to get insight into the metabolic changes resulting from cellular adaptation to changes in the environment and from stress response.

One of the first studies aimed at identifying induced or repressed proteins in Synechocystis cells concerned the light-induced proteins, with changes in the expression of photosynthetic proteins and of chaperones related to general stress response being identified by micro-sequencing and MS [29]. The proteomic study of soluble proteins in cells growing heterotrophically indeed revealed a shift in central carbon metabolism and down-regulation of the photosynthetic machinery [30]. In addition, the analysis of the cytoplasmic and periplasmic proteomes of cells under acidic stress demonstrated that the proteins involved in the response to general stresses are not affected, and that the periplasmic proteome undergoes much greater changes than the cytoplasmic one [31].

In the particular case of hyperosmotic stress, it was shown that the cells face salt stress by increasing not only specific salt-responsive proteins but also many other general stress proteins [32]. The hyperosmotic response of the periplasmic proteome actually results in the salt-enhanced expression of proteins that alter the cell-wall composition and structure [33]. The subsequent analysis of changes in the plasma membrane proteome [34] showed that most ABC transporters are affected. Notwithstanding, it was only possible to identify the more soluble components of the membrane proteins because of the difficulty in separating the integral membrane proteins by classical protocols. Further efforts resulted in the identification of 51 membrane proteins containing transmembrane helices in a range from 1 to 12 [35], whereas the membrane protein complexes were investigated under different culture conditions by using an adapted protocol (Blue native/SDS-PAGE) that allowed the study of 20 distinct protein complexes [36].

In order to increase the throughput and access to proteins difficult to study with the traditional gel-based proteomics, shotgun proteomics has also been applied to Synechocystis. This technique involves sample pre-fractionation and separation, usually by liquid chromatography, before MS [12, 37]. Several sets of proteins have thus been obtained by using different protocols, indicating that the most complete proteomes are obtained when combining different fractionation approaches. Nevertheless, quantification in shotgun proteomics is a complex task as compared with classical proteomics, and no comparative studies regarding measurement of expression levels of cyanobacterial proteins have been completed [12].

Taking all this into account, the proteomic analysis of knockout mutants is an interesting approach to understand how the absence of any specific protein may affect the whole cell metabolism. In this context, a number of studies have been performed with deletion mutants of Synechocystis proteins, namely the FtsH protease (salt-sensitive phenotype), the LepB1 leader peptidase (essential for photoautotrophic growth) and the Hik34 histidine kinase (increased thermal tolerance) [38–40].


   petE AND petJ KNOCKOUT MUTANTS
TOP
 ABSTRACT
 INTRODUCTION
 IRON-COPPER HOMEOSTASIS IN...
 SYNECHOCYSTIS PROTEOMIC STUDIES
 petE AND petJ KNOCKOUT...
Acknowledgements
 References
 
In this context, the effect of copper deprivation on the Synechocystis proteome, with particular emphasis on Pc and Cyt, was analysed because of the relevance of copper and iron homeostasis in cyanobacteria and the ample use of these organisms as model systems for higher plants [6, 41]. We thus constructed the so-called {Delta}petE and {Delta}petJ deletion mutants—the first lacking the Pc-coding petE gene, the second lacking the Cyt-coding petJ gene—and their behaviour when growing in the absence or presence of copper was investigated. Copper is not strictly required by Synechocystis under photoautotrophic conditions, as the wild-type (WT) cells do grow at similar rates with or without copper. Notwithstanding, the two deletion mutants grow at the same rate as the WT strain when cultured in media that allow them to express one of the two electron donor proteins. In fact, {Delta}petJ is only able to grow at a standard rate in the absence of copper, when Cyt is being produced, whereas {Delta}petE only grows when Pc is synthesized upon copper induction. However, when the {Delta}petE and {Delta}petJ strains are growing under conditions at which neither Pc nor Cyt is being expressed, they both show growth rates that are much lower than that of WT cells [10]. This is an interesting observation, and several proposals have been made to explain how these cultures can survive in the absence of both Pc and Cyt. Some authors have suggested the existence of a third (but relatively inefficient) electron donor to PSI [42]. Some others have proposed the formation of a supercomplex between cytochrome b6f and PSI to allow direct electron transfer without requirement of any redox carrier [43]. And others have even discussed the existence of an alternative electron transfer pathway [44].

Taking into account that the cyanobacterial respiratory and photosynthetic electron transfer chains share a number of redox components, namely Cyt, Pc, plastoquinone and cytochrome b6f (Figure 1) [45, 46], the ability of the WT, {Delta}petE and {Delta}petJ strains to grow in glucose-supplemented culture media was also investigated. Under such heterotrophic conditions, glucose is used as an organic carbon source [47] and the electrons are transported from the sugar molecule to dioxygen throughout the respiratory pathway. None of the cell strains (including the WT one) can grow in copper-free medium, as expected from the specific requirement for copper of cytochrome c oxidase [46]. In copper-supplemented medium, however, the WT and {Delta}petJ strains synthesize Pc and show a normal growth level, but the {Delta}petE strain produces neither Cyt nor Pc and is thus unable to grow because of the absence of any electron donor to cytochrome c oxidase.

The in vivo PSI reduction kinetics of the Synechocystis WT and mutant strains were indeed specifically analysed [10]. When the WT cells grow in copper-supplemented culture medium, PSI reduction is just due to Pc (as Cyt synthesis is repressed) and the PSI reduction kinetics are well fitted to the monoexponential curves typical of simple collisional mechanisms [10]. When the WT cells grow in copper-depleted medium, in which Pc synthesis is repressed, the Cyt-dependent PSI reduction follows a biphasic kinetic, which corresponds to a more evolved mechanism [10, 48]. In {Delta}petE and {Delta}petJ cells, growing under conditions that allow the expression of just one of the two electron donor proteins, the in vivo PSI reduction follows kinetics similar to those observed in the WT strain for the same donor protein, but no PSI reduction is detected in mutant cells in which neither Pc nor Cyt is expressed.

The WT and mutant species can be further characterized by fractionation of cells grown either in the absence or in the presence of copper. In the WT strain, in which the soluble fraction and the thylakoidal and plasma membranes can be clearly resolved upon sucrose gradient centrifugation, the absence or presence of copper does not significantly affect the gradient pattern. As regards the deletion mutants, both {Delta}petE in the absence of copper and {Delta}petJ in the presence of copper show a fractional pattern similar to that of WT cells. The extracts of mutant cells in which neither Pc nor Cyt is expressed do exhibit neither the band corresponding to thylakoidal membranes nor the blue colour typical of soluble phycobiliproteins, thereby suggesting that both the membrane organization and the synthesis of accessory pigments are significantly modified because of the lack of electron donors to PSI and to the terminal oxidase [49].

A comparative scheme summarizing the whole proteomic analysis of WT and mutant Synechocystis cells is shown in Figure 2. The soluble fractions of the cell extracts, upon photoautotrophic growth in the absence or presence of copper, are subjected to 2D-electrophoresis, and some of the differentially expressed proteins are selected and analysed by MS. The mutants grown under restrictive conditions show a pattern of over-expressed proteins (thioredoxins, superoxide dismutase, etc.) similar to that induced by oxidative stress. This is as expected because the lack of any redox carrier transferring electrons from cytochrome b6f to PSI blocks the photosynthetic chain, with the concomitant accumulation of photooxidized chlorophyll P700 in PSI, the over-reduction of the quinone pool, the oxidation of the final acceptors and the over-production of ROS. The response of the mutants to such an oxidative stress is the over-expression of peroxiredoxin [50] and the DnaK protein [51]. Moreover, the over-expression of enzymes involved in the main metabolic pathways has also been observed, as expected from the metabolic alteration induced by oxidative stress.


Figure 2
View larger version (27K):
[in this window]
[in a new window]
[Download PowerPoint slide]
  		Figure 2: Proteomic approach to the study of Synechocystis knockout mutants lacking either the petJ or petE genes, which respectively code for cytochrome c6 and plastocyanin. Upon construction of the deletion mutant, an antibiotic-resistance cassette is inserted for the selection of the variant strain. The WT and mutant cells are grown phototrophically in the absence or presence of copper, and the soluble and membrane fractions of the respective cell extracts are analysed by 2D gel-based methods. The overlapping regions of the circles stand for the seven one-to-one comparisons of proteomes that are being analysed. The differences in the patterns of protein expression, in at least three replicates, are determined by using specialized software, with the different proteins being identified by MS.

 
It must also be noted that the {Delta}petJ and {Delta}petE mutants are frequently able to revert spontaneously under restrictive metal conditions, despite they were constructed by using the technique of gene deletion by homologous recombination with an antibiotic-resistance cassette. Thus, the revertants are probably affected in the copper-dependent regulation of some metabolic processes and/or in the metal intake itself. The in-depth characterization of such mutant strains, along with a detailed proteomic analysis of the differential expression of proteins in the WT and knockout mutants at different metal availabilities, will let us understand the complex process of copper homeostasis in cyanobacteria.


Key Points

  • Similar redox chemistries can be performed by either iron or copper containing enzymes, so allowing some organisms to switch between iron or copper proteins under metal starvation.
  • In cyanobacteria, copper is first transported into the cell by a P-type ATPase in the plasma membrane, then chaperoned by Atx1 in the cytoplasm and finally transported into the lumen by a second P-type ATPase in the thylakoidal membrane. In addition, iron intake is mediated by an ABC transporter and chaperoned by bacterioferritin.
  • The cyanobacterium Synechocystis is able to grow photoautotrophically both in the absence and presence of copper by synthesizing copper or iron proteins, respectively, as is the case of the plastocyanin/cytochrome c6 couple.
  • The synergistic use of proteomic techniques and knockout mutants of Synechocystis in which the gene expression is regulated by copper is a powerful strategy to study metal homeostasis in cyanobacteria and get relevant information on their subproteomes and comparative expression profiles.

 


   Acknowledgements
TOP
 ABSTRACT
 INTRODUCTION
 IRON-COPPER HOMEOSTASIS IN...
 SYNECHOCYSTIS PROTEOMIC STUDIES
 petE AND petJ KNOCKOUT...
 Acknowledgements
References
 
This study was funded by Spanish Ministry of Education and Science (BMC2003-00458, BFU2006-01361); European Commission (HPRN-CT-1999-00095); Andalusian Government (CVI-0198).


   FOOTNOTES
 
Berta De la Cerda is a Postdoctoral Researcher at the Instituto de Bioquímica Vegetal y Fotosíntesis (IBVF), a joint centre between the University of Seville and the National Research Council (CSIC).

Ornella Castielli holds a PhD fellowship from the Andalusian Government.

Raúl V. Durán was formerly a PhD student at the IBVF and currently is a Postdoctoral Researcher at Beatson Institute for Cancer Research at Glasgow.

José A. Navarro is a CSIC Tenure Scientist.

Manuel Hervás is Associate Professor of the Seville University.

Miguel A. De la Rosa is Full Professor of the Seville University, and Head of the Unit of Structural and Functional Proteomics at the IBVF.


   References
TOP
 ABSTRACT
 INTRODUCTION
 IRON-COPPER HOMEOSTASIS IN...
 SYNECHOCYSTIS PROTEOMIC STUDIES
 petE AND petJ KNOCKOUT...
 Acknowledgements
 References
 

  1. Messerschmidt A, Huber R, Poulos T, et al, eds. Handbook of Metalloproteins (2001) Chichester, UK: John Wiley & Sons.
  2. Halliwell B, Gutteridge JM. Oxygen toxicity, oxygen radicals, transition metals, & disease. Biochem J (1984) 219:1–14.[Web of Science][Medline]
  3. Crichton RR, Ward RJ, eds. Metal-based Neurodegeneration: From Molecular Mechanisms to Therapeutic Strategies (2006) Chichester, UK: John Wiley & Sons.
  4. Núñez MT, Garrick MD, eds. Special issue-third international workshop on iron, & copper homeostasis. Biol Res (2006) 39:1–201.
  5. Tottey S, Harvie DR, Robinson NJ. Understanding how cells allocate metals using metal-sensors and metallochaperones. Acc Chem Res (2005) 38:775–83.[CrossRef][Web of Science][Medline]
  6. Hervás M, Navarro JA, De la Rosa MA. Electron transfer between membrane complexes and soluble proteins in photosynthesis. Acc Chem Res (2003) 36:798–805.[CrossRef][Web of Science][Medline]
  7. Shcolnick S, Keren N. Metal homeostasis in cyanobacteria and chloroplasts. Balancing benefits and risks to the photosynthetic apparatus. Plant Physiol (2006) 141:805–10.[Free Full Text]
  8. Bryant DA, ed. The Molecular Biology of Cyanobacteria. Advances in Photosynthesis, & Respiration Series (1994) 1. Dordrecht: Kluwer Academic Publishers.
  9. Kaneko T, Sato S, Kotani H, et al. Sequence analysis of the genome of the unicellular cyanobacterium Synechocystis sp. strain PCC6803. II. Sequence determination of the entire genome and assignment of potential protein-coding regions. DNA Res (1996) 3:109–36. available at http://www.kazusa.or.jp/cyano/cyano.html.[Abstract]
  10. Durán RV, Hervás M, De la Rosa MA, et al. The efficient functioning of photosynthesis and respiration in Synechocystis sp. PCC 6803 strictly requires the presence of either cytochrome c6 or plastocyanin. J Biol Chem (2004) 279:7229–33.[Abstract/Free Full Text]
  11. Waldron KJ, Tottey S, Yanagisawa S, et al. Periplasmic iron-binding protein contributes toward inward copper supply. J Biol Chem (2007) 282:3837–46.[Abstract/Free Full Text]
  12. Barrios-Llerena ME, Chong PK, Gan CS, et al. Shotgun proteomics of cyanobacteria - applications of experimental and data-mining techniques. Brief Funct Genom Proteom (2006) 5:121–32.[CrossRef]
  13. Crichton RR, Pierre JL. Old iron, young copper: from Mars to Venus. Biometals (2001) 14:99–112.[CrossRef][Web of Science][Medline]
  14. Merchant S, Allen MD, Kropat J, et al. Between a rock and a hard place: trace element nutrition in Chlamydomonas. Biochim Biophys Acta (2006) 1763:578–94.[Medline]
  15. Ho KK, Krogmann DW. Electron-donors to P700 in cyanobacteria and algae - an instance of unusual genetic-variability. Biochim Biophys Acta (1984) 766:310–6.
  16. Sandmann G, Reck H, Kessler E, et al. Distribution of plastocyanin and soluble plastidic cytochrome c in various classes of algae. Arch Microbiol (1983) 134:23–7.[CrossRef][Web of Science]
  17. Briggs LM, Pecoraro VL, McIntosh L. Copper-induced expression, cloning, and regulatory studies of the plastocyanin gene from the cyanobacterium Synechocystis sp. PCC 6803. Plant Mol Biol (1990) 15:633–42.[CrossRef][Web of Science][Medline]
  18. Zhang L, McSpadden B, Pakrasi HB, et al. Copper-mediated regulation of cytochrome c553 and plastocyanin in the cyanobacterium Synechocystis 6803. J Biol Chem (1992) 267:19054–59.[Abstract/Free Full Text]
  19. Katoh H, Hagino N, Grossman AR, et al. Genes essential to iron transport in the cyanobacterium Synechocystis sp. strain PCC 6803. J Bacteriol (2001) 183:2779–84.[Abstract/Free Full Text]
  20. Aebersold R, Mann M. Mass spectrometry-based proteomics. Nature (2003) 422:198–207.[CrossRef][Medline]
  21. Sazuka T, Ohara O. Towards a proteome project of cyanobacterium Synechocystis sp. strain PCC6803: linking 130 protein spots with their respective genes. Electrophoresis (1997) 18:1252–8.[CrossRef][Web of Science][Medline]
  22. Sazuka T, Yamaguchi M, Ohara O. Cyano2Dbase updated: linkage of 234 protein spots to corresponding genes through N-terminal microsequencing. Electrophoresis (1999) 20:2160–71.[CrossRef][Web of Science][Medline]
  23. Norling B, Mirzakhanian V, Nilsson F, et al. Subfractional analysis of cyanobacterial membranes and isolation of plasma membranes by aqueous polymer two-phase partitioning. Anal Biochem (1994) 218:103–11.[CrossRef][Web of Science][Medline]
  24. Norling B, Zak E, Andersson B, et al. 2D-isolation of pure plasma and thylakoid membranes from the cyanobacterium Synechocystis sp. PCC 6803. FEBS Lett (1998) 436:189–92.[CrossRef][Web of Science][Medline]
  25. Huang F, Parmryd I, Nilsson F, et al. Proteomics of Synechocystis sp. strain PCC 6803: identification of plasma membrane proteins. Mol Cell Proteomics (2002) 1:956–66.[Abstract/Free Full Text]
  26. Wang Y, Sun J, Chitnis PR. Proteomic study of the peripheral proteins from thylakoid membranes of the cyanobacterium Synechocystis sp. PCC 6803. Electrophoresis (2000) 21:1746–54.[CrossRef][Web of Science][Medline]
  27. Huang F, Hedman E, Funk C, et al. Isolation of outer membrane of Synechocystis sp. PCC 6803 and its proteomic characterization. Mol Cell Proteomics (2004) 3:586–95.[Abstract/Free Full Text]
  28. Simon WJ, Hall JJ, Suzuki I, et al. Proteomic study of the soluble proteins from the unicellular cyanobacterium Synechocystis sp. PCC 6803 using automated matrix-assisted laser desorption/ionization-time of flight peptide mass fingerprinting. Proteomics (2002) 2:1735–42.[CrossRef][Web of Science][Medline]
  29. Choi JS, Kim DS, Lee J, et al. Proteome analysis of light induced proteins in Synechocystis sp. PCC 6803: identification of proteins separated by 2D-PAGE using N-terminal sequencing and MALDI-TOF MS. Mol Cell (2000) 10:705–11.[CrossRef][Web of Science]
  30. Kurian D, Jansen T, Mäenpäa P. Proteomic analysis of heterotrophy in Synechocystis sp. PCC 6803. Proteomics (2006) 6:1483–94.[CrossRef][Web of Science][Medline]
  31. Kurian D, Phadwal K, Mäenpää P. Proteomic characterization of acid stress response in Synechocystis sp. PCC 6803. Proteomics (2006) 6:3614–24.[CrossRef][Web of Science][Medline]
  32. Fulda S, Mikkat S, Huang F, et al. Proteome analysis of salt stress response in the cyanobacterium Synechocystis sp. strain PCC 6803. Proteomics (2006) 6:2733–45.[CrossRef][Web of Science][Medline]
  33. Fulda S, Huang F, Nilsson F, et al. Proteomics of Synechocystis sp. PCC 6803. Identification of periplasmic proteins in cells grown at low and high salt concentrations. Eur J Biochem (2000) 267:5900–7.[Web of Science][Medline]
  34. Huang F, Fulda S, Hagemann M, et al. Proteomic screening of salt-stress-induced changes in plasma membranes of Synechocystis sp. strain PCC 6803. Proteomics (2006) 6:910–20.[CrossRef][Web of Science][Medline]
  35. Pisareva T, Shumskaya M, Maddalo G, et al. Proteomics of Synechocystis sp. PCC 6803. Identification of novel integral plasma membrane proteins. FEBS J (2007) 274:791–804.[CrossRef][Medline]
  36. Herranen M, Battchikova N, Zhang PP, et al. Towards functional proteomics of membrane protein complexes in Synechocystis sp. PCC 6803. Plant Physiol (2004) 134:470–81.[Abstract/Free Full Text]
  37. Gan CS, Reardon KF, Wright PC. Comparison of protein and peptide prefractionation methods for the shotgun proteomic analysis of Synechocystis sp. PCC 6803. Proteomics (2005) 5:2468–78.[CrossRef][Web of Science][Medline]
  38. Stirnberg M, Fulda S, Huckauf J, et al. A membrane-bound FtsH protease is involved in osmoregulation in Synechocystis sp. PCC 6803: the compatible solute synthesizing enzyme GgpS is one of the targets for proteolysis. Mol Microbiol (2007) 63:86–102.[CrossRef][Web of Science][Medline]
  39. Zhbanko M, Zinchenko V, Gutensohn M, et al. Inactivation of a predicted leader peptidase prevents photoautotrophic growth of Synechocystis sp. strain PCC 6803. J Bacteriol (2005) 187:3071–8.[Abstract/Free Full Text]
  40. Slabas AR, Suzuki I, Murata N, et al. Proteomic analysis of the heat shock response in Synechocystis PCC 6803 and a thermally tolerant knockout strain lacking the histidine kinase 34 gene. Proteomics (2006) 6:845–64.[CrossRef][Web of Science][Medline]
  41. Malakhov MP, Malakhova OA, Murata N. Balanced regulation of expression of the gen for cytochrome cM and that of genes for plastocyanin and cytochrome c6 in Synechocystis. FEBS Lett (1999) 444:281–4.[CrossRef][Web of Science][Medline]
  42. Metzger SU, Pakrasi HB, Whitmarsh J. Characterization of a double deletion mutant that lacks cytochrome c6 and cytochrome cM in Synechocystis 6803. In: Photosynthesis: From Light to Biosphere—Mathis P, ed. (1995) Dordrecht, The Netherlands: Kluwer Academic Publishers. 823–6.
  43. Schmetterer G. Cyanobacterial respiration. In: The Molecular Biology of Cyanobacteria—Bryant DA, ed. (1994) Dordrecht, The Netherlands: Kluwer Academic Publishers. 409–35.
  44. Berry S, Schneider D, Vermaas WF, et al. Electron transport routes in whole cells of Synechocystis sp. PCC 6803: the role of the cytochrome bd-type oxidase. Biochemistry (2002) 4:3422–9.
  45. Paumann M, Regelsberger G, Obinger C, et al. The bioenergetic role of dioxygen and the terminal oxidase(s) in cyanobacteria. Biochim Biophys Acta (2005) 1707:231–53.[Medline]
  46. Pils D, Gregor W, Schmetterer G. Evidence for in vivo activity of three distinct respiratory terminal oxidases in the cyanobacterium Synechocystis sp. PCC 6803. FEMS Microbiol Lett (1997) 152:83–8.[CrossRef][Web of Science]
  47. Anderson SL, McIntosh L. Light-activated heterotrophic growth of the cyanobacterium Synechocystis sp. PCC 6803: a blue-light-requiring process. J Bacteriol (1991) 173:2761–7.[Abstract/Free Full Text]
  48. Durán RV, Hervás M, De la Rosa MA, et al. A laser flash-induced kinetic analysis of in vivo photosystem I reduction by site-directed mutants of plastocyanin and cytochrome c6 in Synechocystis sp. PCC 6803. Biochemistry (2006) 45:1054–60.[CrossRef][Web of Science][Medline]
  49. Castielli O, Durán RV, Hervás M, et al. A proteomic study of knockout mutants of Synechocystis sp. PCC 6803 lacking either cytochrome c6 or plastocyanin. In: Abstracts of the Workshop on Trends in Transient Interactions between Biological Macromolecules (2007) Seville, Spain: Federation of European Biochemical Societies. Abstract P-7.
  50. Kobayashi M, Ishizuka T, Katayama M, et al. Response to oxidative stress involves a novel peroxiredoxin gene in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Plant Cell Physiol (2004) 45:290–9.[Abstract/Free Full Text]
  51. Deuerling E, Schulze-Specking A, Tomoyasu T, et al. Trigger factor and DnaK cooperate in folding of newly synthesized proteins. Nature (1999) 400:693–6.[CrossRef][Medline]

Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?



This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
6/4/322    most recent
elm030v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Cerda, B. D. l.
Right arrow Articles by Rosa, M. A. D. l.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Cerda, B. D. l.
Right arrow Articles by Rosa, M. A. D. l.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?