Photosystem I reaction‐centre proteins contain leucine zipper motifs

Webber, Andrew N.; Malkin, Richard

doi:10.1016/0014-5793(90)80749-9

Cited by 46 publications

(23 citation statements)

References 22 publications

(13 reference statements)

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“…This result suggests that the hydrophobic helices of CPI must have high binding affinity. Perhaps this stability also supports the postulation of a leucine zipper binding the two subunits together, in the region of helix VIII and the following sequence that leads to the conserved Cys-containing region (28). The shared Fx, which might stabilize the dimer, is lost during preparation of CPI by the method used here.…”

Section: Cpisupporting

confidence: 71%

Organization and Topology of Photosystem I Subunits

Zilber¹,

Malkin²

1992

Plant Physiol.

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Intact spinach (Spinacia oleracea) thylakoid membranes were treated with various proteases and photosystem I (PSI) complexes were isolated from these membranes to define the membrane topology of specific PSI subunits. Trypsin treatment caused cleavage of the PSI-D and E subunits. Thermolysin treatment cleaved the PSI-D, E, H, and K subunits, and also caused limited degradation of the reaction center core PSI-A and B subunits. Pronase treatment produced the most dramatic results as the PSI-A and B subunits were cleaved to 47-, 45-, 26-, and 24-kilodalton products. In addition, pronase degraded the PSI-D, E, H, K, and L subunits. Proteolytic cleavage sites for several of the products were identified by amino acid sequencing. The results indicate that PSI-A, B, D, E, H, K, and L subunits all have stroma-exposed regions, and these findings are summarized in a model describing the subunit organization of PSI.

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Section: Cpisupporting

confidence: 71%

Organization and Topology of Photosystem I Subunits

Zilber¹,

Malkin²

1992

Plant Physiol.

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“…Therefore, we must rely on the current body of biochemical and biophysical data and analysis of evolutionary conservation to identify residues that may serve as important structural and/or functional components in the complex. The most convincing evidence for the roles of particular residues in the PSI reaction center addresses the possible ligands to the [4Fe4S] center Fx (5) and the role of a putative leucine zipper in the PsaA and PsaB proteins (6,7). Cysteine residues, with few exceptions, serve as the ligands to [4Fe-4S] centers (5).…”

mentioning

confidence: 99%

“…1). The cysteine residues proposed to coordinate Fx lie in a position analogous to the DNA-binding region of regulatory proteins (6,7).…”

mentioning

confidence: 99%

Mutational analysis of the structure and biogenesis of the photosystem I reaction center in the cyanobacterium Synechocystis sp. PCC 6803.

Smart

Warren

Golbeck

et al. 1993

Proc. Natl. Acad. Sci. U.S.A.

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We have utilized the unicellular cyanobacterium Synechocystis sp. PCC 6803 to incorporate site-directed amino acid substitutions into the photosystem I (PSI) reactioncenter protein PsaB. A cysteine residue (position 565 of PsaB) proposed to serve as a ligand to the [4Fe-4S] center Fx was changed to serine, histidine, and aspartate. These three mutants--C565S, C565H, and C565D--all exhibited greatly reduced accumulation of PSI reaction-center proteins and failed to grow autotrophically, indicating that this cysteine most likely does coordinate Fx, which is crucial for PSI biogenesis. Interestingly, the strain C565S accumulated significantly more PSI than the other two cysteine mutants and displayed photoreduction of the [4Fe-4S] terminal electron acceptors FA and FB. Mutations were also introduced into a leucine zipper motif of PsaB, proposed to participate in reaction-center dimerization. The mutants L522V, L536M, and L522V/L536M all exhibited wild-type characteristics and grew autotrophically, whereas the L522P mutation prevented PSI accumulation. These data do not provide support for a major structural role of the leucine zipper in reaction-center dimerization or in assembly of Fx. However, the amino acid substitutions incorporated were conservative and might not have perturbed the leucine zipper.

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“…The intervening amino acid residues are highly conserved in oxygenic photosynthetic organisms [1 ] and possibly contain residues involved in binding the primary electron donor, P700 and electron transport components Ao and A~. In addition, Webber and Malkin [16] have proposed that a leucine zipper motif in this region facilitates interaction of the reaction center heterodimer. Therefore, we will be able to utilize the StuI site as a transformation marker and the ac-u-g-2.3 strain as a convenient recipient of further site-directed mutations designed to elucidate those residues coded in psaB which are directly involved in photosystem I assembly and function.…”

Section: Discussionmentioning

confidence: 99%

Transformation of chloroplasts with thepsaB gene encoding a polypeptide of the photosystem I reaction center

Bingham

Webber

1991

FEBS Letters

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A chloroplast photosystem I reaction center mutation, at-u-g-2.3, of Chlamydomonas reinhardtii has been complemented with a wild type psaB gene to restore photosynthetic competence. The mutation was mapped in the psaB coding sequence by chloroplast transformation using subcloned restriction fragments ofpsaB. The mutation was found to be a single base pair deletion resulting in a reading frame shift and premature termination of the polypeptide. Transformants were verified by insertion of a site-directed mutation which created a new restriction enzyme site. These transformations demontrate the feasibility of insertion of site-directed mutations into the psaB gene in order to elucidate amino acid residues involved in photosystem I assembly and function.

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Photosystem I reaction‐centre proteins contain leucine zipper motifs

Cited by 46 publications

References 22 publications

Organization and Topology of Photosystem I Subunits

Organization and Topology of Photosystem I Subunits

Mutational analysis of the structure and biogenesis of the photosystem I reaction center in the cyanobacterium Synechocystis sp. PCC 6803.

Transformation of chloroplasts with thepsaB gene encoding a polypeptide of the photosystem I reaction center

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