Assembly of the photosystem II oxygen-evolving complex is inhibited in psbA site-directed mutants of Chlamydomonas reinhardtii: aspartate 170 of the D1 polypeptide

Photosystem II catalyzes the photooxidation of water to molecular oxygen, providing electrons to the photosynthetic electron transfer chain. The D1 and D2 chloroplast-encoded reaction center polypeptides bind cofactors essential for Photosystem II function. Transformation of the chloroplast genome o...

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Bibliographic Details
Published in:The Journal of biological chemistry 1995-01, Vol.270 (1), p.225-235
Main Authors: Whitelegge, J.P. (University of California, Los Angeles, CA.), Koo, D, Diner, B.A, Domian, I, Erickson, J.M
Format: Article
Language:English
Subjects:
ACIDE ASPARTIQUE
ACIDO ASPARTICO
Animals
Aspartic Acid - genetics
Aspartic Acid - metabolism
Base Sequence
Chlamydomonas reinhardtii
Chlamydomonas reinhardtii - metabolism
CHLOROPHYCEAE
Chloroplasts - metabolism
Codon
FOTOSISTEMAS
Freshwater
INHIBICION
INHIBITION
Light-Harvesting Protein Complexes
Molecular Sequence Data
MUTACION INDUCIDA
Mutagenesis, Site-Directed
MUTANT
MUTANTES
MUTATION PROVOQUEE
Oligodeoxyribonucleotides
OXIGENO
Oxygen - metabolism
OXYGENE
PEPTIDE
PEPTIDOS
Photosynthetic Reaction Center Complex Proteins - chemistry
Photosynthetic Reaction Center Complex Proteins - genetics
Photosynthetic Reaction Center Complex Proteins - metabolism
Photosystem II Protein Complex
PHOTOSYSTEME
Spectrometry, Fluorescence
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Summary:Photosystem II catalyzes the photooxidation of water to molecular oxygen, providing electrons to the photosynthetic electron transfer chain. The D1 and D2 chloroplast-encoded reaction center polypeptides bind cofactors essential for Photosystem II function. Transformation of the chloroplast genome of the eukaryotic green alga Chlamydomonas reinhardtii has allowed us to engineer site-directed mutants in which aspartate residue 170 of D1 is replaced by histidine (D170H), asparagine (D170N), threonine (D170T), or proline (D170P). Mutants D170T and D170P are completely deficient in oxygen evolution, but retain normal (D170T) or 50% (D170P) levels of Photosystem II reaction centers. D170H and D170N accumulate wild-type levels of PSII centers, yet evolve oxygen at rates approximately 45% and 16% those of control cells, respectively. Kinetic analysis of chlorophyll fluorescence in the mutants reveals a specific defect in electron donation to the reaction center. Measurements of oxygen flash yields in D170H show, however, that those reaction centers capable of evolving oxygen function normally. We conclude that aspartate residue 170 of the D1 polypeptide plays a critical role in the initial binding of manganese as the functional chloroplast oxygen-evolving complex is assembled
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.270.1.225