Artículo
Oxidizing Side of the Cyanobacterial Photosystem I
Autor/es | Sun, J.
Xu, W. Hervás Morón, Manuel Navarro Carruesco, José Antonio Rosa Acosta, Miguel Ángel de la Chitnis, Parag R. |
Departamento | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular |
Fecha de publicación | 1999 |
Fecha de depósito | 2022-06-07 |
Publicado en |
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Resumen | Photosystem I (PSI) interacts with plastocyanin or cytochrome c 6 on the luminal side. To identify sites of interaction between plastocyanin/cytochromec 6 and the PSI core, site-directed mutations were generated in the ... Photosystem I (PSI) interacts with plastocyanin or cytochrome c 6 on the luminal side. To identify sites of interaction between plastocyanin/cytochromec 6 and the PSI core, site-directed mutations were generated in the luminal J loop of the PsaB protein fromSynechocystis sp. PCC 6803. The eight mutant strains differed in their photoautotrophic growth. Western blotting with subunit-specific antibodies indicated that the mutations affected the PSI level in the thylakoid membranes. PSI proteins could not be detected in the S600R/G601C/N602I, N609K/S610C/T611I, and M614I/G615C/W616A mutant membranes. The other mutant strains contained different levels of PSI proteins. Among the mutant strains that contained PSI proteins, the H595C/L596I, Q627H/L628C/I629S, and N638C/N639S mutants showed similar levels of PSI-mediated electron transfer activity when either cytochrome c 6 or an artificial electron donor was used. In contrast, cytochromec 6 could not function as an electron donor to the W622C/A623R mutant, even though the PSI activity mediated by an artificial electron donor was detected in this mutant. Thus, the W622C/A623R mutation affected the interaction of the PSI complex with cytochrome c 6. Biotin-maleimide modification of the mutant PSI complexes indicated that His-595, Trp-622, Leu-628, Tyr-632, and Asn-638 in wild-type PsaB may be exposed on the surface of the PSI complex. The results presented here demonstrate the role of an extramembrane loop of a PSI core protein in the interaction with soluble electron donor proteins. |
Cita | Sun, J., Xu, W., Hervás Morón, M., Navarro Carruesco, J.A., Rosa Acosta, M.Á.d.l. y Chitnis, P.R. (1999). Oxidizing Side of the Cyanobacterial Photosystem I. Journal of Biological Chemistry, 274 (27), 19048-19054. |
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