Article

PsaL subunit is required for the formation of photosystem I trimers in the cyanobacterium Synechocystis sp. PCC 6803

Division of Biology, Kansas State University, Manhattan 66506-4901.
FEBS Letters (Impact Factor: 3.34). 01/1994; 336(2):330-4. DOI: 10.1016/0014-5793(93)80831-E
Source: PubMed

ABSTRACT When membranes of the wild type strain of the cyanobacterium Synechocystis sp. PCC 6803 were solubilized with detergents and fractionated by sucrose-gradient ultracentrifugation, photosystem I could be obtained as trimers and monomers. We could not obtain trimers from the membranes of any mutant strain that lacked PsaL subunit. In contrast, absence of PsaE, PsaD, PsaF, or PsaJ did not completely abolish the ability of photosystem I to form trimers. Furthermore, PsaL is accessible to digestion by thermolysin in the monomers but not in the trimers of photosystem I purified from wild type membranes. Therefore, PsaL is necessary for trimerization of photosystem I and may constitute the trimer-forming domain in the structure of photosystem I.

Full-text

Available from: Parag R Chitnis, Mar 14, 2014
0 Followers
 · 
71 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Synechocystis sp. PCC 6803 is a model cyanobacterium extensively used to study photosynthesis. Here we reveal a novel high light-inducible carotenoid-binding protein complex (HLCC) in the thylakoid membranes of Synechocystis PCC 6803 cells exposed to high intensity light. Zeaxanthin and myxoxanthophyll accounted for 29.8% and 54.8%, respectively, of the carotenoids bound to the complex. Using Blue-Native PAGE followed by 2D SDS-PAGE and mass spectrometry, we showed that the HLCC consisted of Slr1128, IsiA, PsaD, and HliA/B. We confirmed these findings by SEAD fluorescence cross-linking and anti-PsaD immuno-coprecipitation analyses. The expression of genes encoding the protein components of the HLCC was enhanced by high light illumination and artificial oxidative stress. Deletion of these proteins resulted in impaired state transition and increased sensitivity to oxidative and/or high light stress, as indicated by increased membrane peroxidation. Therefore, the HLCC protects thylakoid membranes from extensive photooxidative damage, likely via a mechanism involving state transition. E xposure to high-intensity light (HL) adversely affects the photosynthetic performance, cell growth, and viability of photosynthetic organisms. The damage is largely attributed to oxygen-dependent destruction of the photosynthetic apparatus and other cellular components 1,2. Oxygenic photosynthetic organisms synthesize stress-associated proteins during exposure to HL. These proteins are often important for the acclimation of cells to HL. A family of HL-inducible genes, called hli or scp genes 3,4
    Scientific Reports 03/2015; 5:9480. DOI:10.1038/srep09480 · 5.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Bioenergetic reactions in chloroplasts and mitochondria are catalyzed by large multi-subunit membrane proteins. About two decades ago it became clear that several of these large membrane proteins further associate into supercomplexes and since then a number of new ones have been described. In this review we focus on supercomplexes involved in light harvesting and electron transfer in the primary reactions of oxygenic photosynthesis and on the mitochondrial supercomplexes that catalyze electron transfer and ATP synthesis in oxidative phosphorylation. Functional and structural aspects are overviewed. In addition, several relevant technical aspects are discussed, including membrane solubilization with suitable detergents and methods of purification. Some open questions are addressed, such as the lack of high-resolution structures, the outstanding gaps in the knowledge about supercomplexes involved in cyclic electron transport in photosynthesis and the unusual mitochondrial protein complexes of protists and in particular of ciliates. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.
    Micron 03/2015; 72:39-51. DOI:10.1016/j.micron.2015.03.002 · 2.06 Impact Factor
  • Source