Photosynthetic electron transport in genetically altered photosystem II reaction centers of chloroplasts

Using a cotransformation system to identity chloroplast transformants in Chlamydomonas reinhardtii, we converted histidine-195 of the photosystem II reaction center D1 protein to a tyrosine residue. The mutants were characterized by a reduced quantum efficiency for photosynthetic oxygen evolution, w...

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Bibliographic Details
Published in:	Proceedings of the National Academy of Sciences - PNAS Vol. 88; no. 20; pp. 9122 - 9126
Main Authors:	Roffey, R.A. (Ohio State University, Columbus, OH), Golbeck, J.H, Hille, C.R, Sayre, R.T
Format:	Journal Article
Language:	English
Published:	Washington, DC National Academy of Sciences of the United States of America 15-10-1991 National Acad Sciences
Subjects:	ADN Animals Biological and medical sciences Cell structures and functions Chlamydomonas - genetics Chlamydomonas - metabolism Chlamydomonas reinhardtii CHLOROPHYCEAE Chloroplast, photosynthetic membrane and photosynthesis CHLOROPLASTE Chloroplasts Chloroplasts - metabolism CLOROPLASTO DNA - genetics DNA - isolation & purification Electron Spin Resonance Spectroscopy Electron Transport Electrons FOTOSINTESIS Fundamental and applied biological sciences. Psychology genes GENETICA GENETIQUE Genome Genomes Kinetics Light Light-Harvesting Protein Complexes Molecular and cellular biology Mutagenesis, Site-Directed MUTANT MUTANTES Oxidation OXIRREDUCION OXYDOREDUCTION Oxygen Phenotype PHOTOSYNTHESE Photosynthesis Photosynthetic Reaction Center Complex Proteins - genetics Photosynthetic Reaction Center Complex Proteins - metabolism Photosystem II Photosystem II Protein Complex Plant cells Plasmids reaction centers Restriction Mapping Thylakoids TIROSINA TYROSINE Oxidation reduction Genetic transformation Reaction center Algae Chlorophycophyta Site directed mutagenesis EPR spectrometry Electron transfer Structure function relationship Photosystem 2 Chlamydomonas reinhardtii Photosynthesis Chloroplast Thallophyta
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Summary:	Using a cotransformation system to identity chloroplast transformants in Chlamydomonas reinhardtii, we converted histidine-195 of the photosystem II reaction center D1 protein to a tyrosine residue. The mutants were characterized by a reduced quantum efficiency for photosynthetic oxygen evolution, which varied in a ph-dependent manner, a reduced capacity to oxidize artificial donors to photosystem II, and P680+ reduction kinetics (microsecond) that were essentially similar to wild type. In addition, a dark-stable radical was detected by ESR in mutant photosystem II particles but not in wild-type particles. This radical was similar in g value and lineshape to chlorophyll or carotenoid cations but could have arisen from a tyrosine-195 cation. The ability of the photosystem 11 trap (P680+) to oxidize tyrosine residues suggests that the mutant tyrosine residue could be used as a redox-sensitive probe to investigate the environment around the photosystem II trap
Bibliography:	F60 F30 9173346 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0027-8424 1091-6490
DOI:	10.1073/pnas.88.20.9122