The Eight-amino Acid Internal Loop of PSI-C Mediates Association of Low Molecular Mass Iron-Sulfur Proteins with the P700-FXCore in Photosystem I

Naver, Helle; Scott, M. Paul; Golbeck, John H.; Olsen, Carl Erik; Scheller, Henrik Vibe

doi:10.1074/jbc.273.30.18778

Cited by 12 publications

(4 citation statements)

References 50 publications

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“…In the case of PsaC, the C-terminus is significantly longer (14-15 amino acids) than in typical bacterial dicluster ferredoxins, and it is this region that has been shown to orient PsaC in one of two possible configurations on the heterodimeric core of PS I (Antonkine et al 2003;Jagannathan and Golbeck 2009c). PsaC also contains an eight amino acid insertion between the Fe/S cluster binding motifs that interacts with ferredoxin and flavodoxin (Naver et al 1998). A sequence comparison of PshBI and PsaC shows that both of these features are missing in PshBI (Heinnickel et al 2007).…”

Section: Pshbi and Pshbii The Proteins Harboring The F A And F B Clumentioning

confidence: 97%

The bound iron–sulfur clusters of Type-I homodimeric reaction centers

Romberger

Golbeck

2010

Photosynth Res

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The hallmark of a Type-I photosynthetic reaction center (RC) is the presence of three [4Fe-4S](2+/1+) clusters, named F(X), F(A), and F(B) that act as terminal electron acceptors. Their function is to increase the distance, and hence the lifetime, of the initial charge-separated state so that diffusion-mediated processes, such as the reduction of ferredoxin, can occur. Type-I homodimeric RCs, such as those found in heliobacteria, green-sulfur bacteria, and Candidatus Chloracidobacterium thermophilum, are less well understood than Photosystem I, the prototypical Type-I heterodimeric RC found in cyanobacteria and plants. Here, we review recent progress that has been made in elucidating the spectroscopic and biochemical properties of the bound Fe/S clusters and their cognate proteins in homodimeric Type-I RCs. In Heliobacterium modesticaldum, the identification and characterization of two loosely bound polypeptides, PshBI and PshBII that harbor the F(A) and F(B) clusters threatens to break the long-accepted assumption that Type-I RCs harbor one tightly bound F(A)/F(B)-containing protein. Additionally, the detection of the F(X) cluster in S = 1/2 and S = 3/2 ground spin states has resolved the long-standing issue of its missing EPR spectrum. In Chlorobaculum tepidum, the focus is on the biochemical properties of the unusual extrinsic Fe/S protein, PscB, which is readily dissociable from the RC core. The C-terminal domain of PscB is constructed as a bacterial ferredoxin, harboring the F(A) and F(B) clusters, but the N-terminal domain contains a number of PxxP motifs and is rich in Lys, Pro, and Ala residues, features characteristic of proteins that interact with SH3 domains. Little is known about Candidatus Chloracidobacterium thermophilum except that the photosynthetic RC is predicted to be a Type-I homodimer with an F(X)-binding site. These findings are placed in a context that promises to unify the acceptor side of homodimeric Type-I RCs in prokaryotic phototrophs.

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Section: Pshbi and Pshbii The Proteins Harboring The F A And F B Clumentioning

confidence: 97%

The bound iron–sulfur clusters of Type-I homodimeric reaction centers

Romberger

Golbeck

2010

Photosynth Res

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“…4,24 Furthermore, the insertion of a small piece of sequence from PsaC into a soluble ferredoxin can mediate functional binding of ferredoxin and electron transfer from the PS I core to ferredoxin, even without the binding of PsaD and PsaE. 25 Therefore one may speculate that the divergent evolution of a type I reaction center may have resulted from the ancestor of PS I ''catching'' a ferredoxin, containing two 4Fe4S clusters. The PS I ancestor later permanently incorporated the protein into the PS I complex and stabilized it by the addition of the stromal subunits PsaE and PsaD.…”

Section: B the Electron Transfer Chainmentioning

confidence: 99%

Evolution of photosynthesis and oxygen evolution: Implications from the structural comparison of Photosystems I and II

Grotjohann

Jolley

Fromme

2004

Phys. Chem. Chem. Phys.

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Two large membrane protein complexes, Photosystem I and II (PS I and PS II), perform the first step in the conversion of the light energy from the sun into chemical energy: the light-induced transmembrane charge separation. They function in series; PS II provides the strong positive redox potential for water oxidation, while PS I generates a strong negative redox potential, which makes it able to reduce ferredoxin and deliver the electrons for the reduction of hydrogen in the form of NADPH. The structural comparison of PS I and PS II sheds light on the evolution of oxygenic photosynthesis. Both Photosystems show similarities in their core structure, indicating that they have been derived from a common ancestor. Striking differences in the arrangement and coordination of cofactors and in their protein environment, however, may contain the secret to the functional differences between the Photosystems. In this article, we address how the oxygen-evolving complex may have developed, and the main similarities and differences in the electron carriers and the organization of the antenna systems of these two complexes.

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“…A specific interaction of Ycf3 with all the PSI subunits appears unlikely, however, given that the assembly requirements for the different PSI subunits are diverse. The iron-sulfur clusters of PsaC are oxygen labile except when the subunit is situated on the PSI complex protected by PsaA, PsaB, and PsaD (Oh-oka et al, 1988;Mehari et al, 1991;Naver et al, 1996Naver et al, , 1998. This subunit is likely to require a chaperone to stabilize its conformation outside the PSI complex.…”

Section: Ycf3 Interacts With At Least Two Psi Subunitsmentioning

confidence: 99%

Functional Studies of Ycf3

2001

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The Ycf3 protein is essential for the accumulation of the photosystem I (PSI) complex and acts at a post-translational level. The sequence of Ycf3 is conserved in cyanobacteria, algae, and plants and contains three tetratrico-peptide repeats (TPR). TPRs have been shown to function as sites for protein-protein interactions. The mutations Y95A/Y96A and Y142A/W143A in the second and third TPR repeats lead to a modest decrease of PSI, but they prevent photoautotrophic growth and cause enhanced light sensitivity even though the accumulated PSI complex is fully functional. This phenotype can be reversed under anaerobic conditions and appears to be the result of photooxidative damage. A temperature-sensitive ycf3 mutant, generated by random mutagenesis of a conserved region near the N-terminal end of Ycf3, was used in temperature-shift experiments to show that Ycf3 is required for PSI assembly but not for its stability. Immunoblot analysis of thylakoid membranes separated by two-dimensional gel electrophoresis and immunoprecipitations shows that Ycf3 interacts directly with the PSI subunits PsaA and PsaD, but not with subunits from other photosynthetic complexes. Thus, Ycf3 appears to act as a chaperone that interacts directly and specifically with at least two of the PSI subunits during assembly of the PSI complex.

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The Eight-amino Acid Internal Loop of PSI-C Mediates Association of Low Molecular Mass Iron-Sulfur Proteins with the P700-FXCore in Photosystem I

Cited by 12 publications

References 50 publications

The bound iron–sulfur clusters of Type-I homodimeric reaction centers

The bound iron–sulfur clusters of Type-I homodimeric reaction centers

Evolution of photosynthesis and oxygen evolution: Implications from the structural comparison of Photosystems I and II

Functional Studies of Ycf3

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