Interaction between Photosystem I and Flavodoxin from the Cyanobacterium <i>Synechococcus</i> sp. PCC 7002 as Revealed by Chemical Cross‐Linking

Mühlenhoff, Ulrich; Zhao, Jindong; Bryant, Donald A.

doi:10.1111/j.1432-1033.1996.00324.x

Cited by 42 publications

(47 citation statements)

References 59 publications

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“…The PsaC-D cross-link induced with the zero-length cross-linker EDC (see Fig. 3) indicates a close proximity of these two subunits, which has already been suggested by cross-linking experiments with PS1 from S. elongatus (35) and (with a 12-Å cross-linker) in PS1 from higher plants (43). For PS1 from (Fig.…”

Section: Discussionsupporting

confidence: 66%

“…7), is also in agreement with the formation of a cross-link complex between PsaE and PsaF using EDC. Such a cross-link complex was also found in other cyanobacteria and in higher plants (35,43). The existence of a hydrophobic "anchor" for PsaF was also deduced from the absence of extracted subunit upon treatment of purified PS1 with chaotropes (4,50,51).…”

Section: Discussionmentioning

confidence: 67%

“…6, A-H), which is consistent with only one specific subunit missing in each case. This allowed the localization of subunits PsaC, -D, -E, -F, and -J, a localization supported by biochemical (33)(34)(35) and mutagenesis experiments (13,30,36,37). Based on this set of new data we developed a model for the arrangement of the major subunits of PS1 (Fig.…”

Section: Discussionmentioning

confidence: 95%

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Structural Organization of the Major Subunits in Cyanobacterial Photosystem 1

Kruip¹,

Chitnis²,

Lagoutte³

et al. 1997

Journal of Biological Chemistry

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Based on an improved isolation procedure using perfusion chromatography, trimeric Photosystem 1 (PS1) complexes have been isolated from various deletion mutants of the mesophilic cyanobacterium Synechocystis PCC 6803. These mutants are only deficient in the deleted subunits, which was carefully checked by high resolution gel electrophoresis in combination with immunoblotting. These highly purified and well characterized PS1 particles were then examined by electron microscopy, followed by computer-aided image processing with single particle averaging techniques as described earlier (Kruip, J., Boekema, E. J., Bald, D., Boonstra, A. Photosystem 1 (PS1) 1 is one of the two transmembrane pigment-protein complexes of oxygenic photosynthesis located in the thylakoid membrane of chloroplasts and cyanobacteria. Its main function is the light-dependent electron transfer from plastocyanin (or cytochrome c 6 ) on the lumen side to soluble ferredoxin (or flavodoxin) on the cytoplasmic or stroma side, thereby transforming light energy into reducing power for various biosynthetic pathways (see Refs. 1-3 for reviews). Cyanobacterial PS1 consists of 11 subunits, named PsaA to PsaM, with PsaG and PsaH missing, as they are found only in chloroplasts (3); all their sequences are known (1). The hydrophilic subunits PsaC, -D, and -E are localized on the cytoplasmic side (4), and PsaF is supposed to sit on the lumenal side of the thylakoid membrane. All the other subunits are integral membrane proteins.In terms of function the initial steps of light harvesting and charge separation are carried out by only three proteins. The PsaA/PsaB heterodimer harbors the primary electron donor P700 (a chlorophyll dimer) and the electron acceptors A 0 (a monomeric chlorophyll), A 1 (a phylloquinone), and F X (a [4Fe4S] iron-sulfur cluster) in addition to about 100 -130 antenna chlorophyll molecules (5). PsaC contains the terminal electron acceptors F A and F B (both [4Fe4S] iron-sulfur clusters). The other proteins do not bind any cofactors, but fulfill important functional and structural roles: PsaD and -F have been shown to be candidates for ferredoxin (6, 7) and plastocyanin docking (8, 9), respectively. PsaE plays an important role in cyclic electron flow (10) and ferredoxin reduction (11,12), while PsaL and PsaD are important for trimer formation (4,13,14).To elucidate the function of all subunits on a molecular level, a high resolution structure is necessary. Despite several crystallization reports (15-17), a low-resolution x-ray analysis (6 Å) for PS1 from the thermophilic cyanobacterium Synechococcus elongatus became available only in 1993 (18). Recently this x-ray analysis was extended to 4 Å (19, 57). In this study, 31 transmembrane, 9 surface, and 3 stromal ␣-helices, 65 chlorophyll a molecules, and three [4Fe4S] clusters could be fitted into the electron density map. Due to the medium resolution it is not possible to attribute the identified structural elements * The costs of publication of this article were defrayed in part by the pay...

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Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 95%

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Structural Organization of the Major Subunits in Cyanobacterial Photosystem 1

Kruip¹,

Chitnis²,

Lagoutte³

et al. 1997

Journal of Biological Chemistry

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“…Rates of ferredoxin-mediated NADP ϩ photoreduction were measured in a 1.3-ml volume using 5 M spinach ferredoxin and 0.8 M spinach ferredoxin:NADP ϩ oxidoreductase (Sigma), and DM-PS I at 5 g ml Ϫ1 of chlorophyll in 50 mM Tricine, pH 8.0, 10 mM MgCl 2 , 15 M cytochrome c 6 from S. maxima, 6 mM sodium ascorbate, 0.05% DM, 0.5 mM NADP ϩ , 0.1% ␤-mercaptoethanol. The flavodoxin was purified from the a strain of E. coli containing the gene by DEAE-Sepharose CL-6B and Sephadex G-75 (both from Sigma) (26,27). NADP ϩ reduction were measured by monitoring the rate of change in the absorption of NADPH at 340 nm.…”

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confidence: 99%

Strains of Synechocystis sp. PCC 6803 with Altered PsaC

Vassiliev

Jung

et al. 1997

Journal of Biological Chemistry

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“…However, its structure contains an SH3 domain, suggesting that it may interact with other proteins (Cesareni et al, 2002). Protein cross-linking studies show that PsaE strongly influences the interaction of proteins on the acceptor side of PSI (Muhlenhoff et al, 1996).…”

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confidence: 99%

FesM, a Membrane Iron-Sulfur Protein, Is Required for Cyclic Electron Flow around Photosystem I and Photoheterotrophic Growth of the Cyanobacterium Synechococcus sp. PCC 7002

Liu

Zhao

et al. 2005

Plant Physiology

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While it is known that cyclic electron flow around photosystem I is an important pathway of photosynthetic electron transfer for converting light energy to chemical energy, some components of cyclic electron flow remain to be revealed. Here, we show that fesM, encoding a novel membrane iron-sulfur protein, is essential to cyclic electron flow in the cyanobacterium Synechococcus sp. PCC 7002. The FesM protein is predicted to have a cAMP-binding domain, an NtrC-like domain, a redox sensor motif, and an iron-sulfur (4Fe-4S) motif. Deletion of fesM (fesM-D) led to an inability for Synechococcus cells to grow in the presences of glycerol and 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Photoheterotrophic growth was restored by a complete fesM gene present on a replicable plasmid. A mutant fesM gene encoding a truncated FesM protein lacking the cAMP domain failed to restore the phenotype, suggesting this domain is important to the function of FesM. Measurements of reduction of P700+ and the redox state of interphotosystem electron carriers showed that cells had a slower rate of respiratory electron donation to the interphotosystem electron transport chain, and cyclic electron flow around photosystem I in fesM-D was impaired, suggesting that FesM is a critical protein for respiratory and cyclic electron flow. Phosphatase fusion analysis showed that FesM contains nine membrane-spanning helices, and all functional domains of FesM are located on the cytoplasmic face of the thylakoid membranes.

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Interaction between Photosystem I and Flavodoxin from the Cyanobacterium Synechococcus sp. PCC 7002 as Revealed by Chemical Cross‐Linking

Cited by 42 publications

References 59 publications

Structural Organization of the Major Subunits in Cyanobacterial Photosystem 1

Structural Organization of the Major Subunits in Cyanobacterial Photosystem 1

Strains of Synechocystis sp. PCC 6803 with Altered PsaC

FesM, a Membrane Iron-Sulfur Protein, Is Required for Cyclic Electron Flow around Photosystem I and Photoheterotrophic Growth of the Cyanobacterium Synechococcus sp. PCC 7002

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