Directed mutagenesis indicates that the donor to P sup + sub 680 in photosystem II is tyrosine-161 of the D1 polypeptide

Journal Article · Tue Dec 27 00:00:00 EST 1988 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00426a001· OSTI ID:5565116

Debus, R J; Barry, B A; Sithole, I; Babcock, G T; McIntosh, L ^[1]

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1. Michigan State Univ., East Lansing (USA)

Photosystem II contains two redox-active tyrosines. One of these, Y{sub Z}, reduces the reaction center chlorophyll, P680, and transfers the oxidizing equivalent to the oxygen-evolving complex. The second, Y{sub D}, has a long-lived free radical state of unknown function. The authors, recently established that Y{sub D} is Tyr-160 of the D2 polypeptide by site-directed mutagenesis of a psbD gene in the unicellular cyanobacterium Synechocystis 6803. Y{sub Z} is most likely the symmetry-related Tyr-161 of the D1 polypeptide. To test this hypothesis, they have changed Tyr-161 to phenylalanine by site-directed mutagenesis of a psb A gene in Synechocystis. The resulting mutant assembles PSII, as judged by its ability to produce the stable Y{sup +}{sub D} radical, but is unable to grow photosynthetically and exhibits altered fluorescence properties. The nature of the fluorescence change indicates that forward electron transfer to P{sup +}{sub 680} is disrupted in the mutant. These results provide strong support for our identification of Tyr-161 in the D1 polypeptide with Y{sub Z}.

• OSTI ID: 5565116
• Journal Information: Biochemistry; (USA), Vol. 27:26; ISSN 0006-2960
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
DNA
HYBRIDIZATION
PHOTOSYNTHETIC REACTION CENTERS
ELECTRON TRANSFER
POLYPEPTIDES
MUTAGENESIS
CHLOROPHYLL
GENES
MUTANTS
PHENYLALANINE
PHOSPHORUS 32
TYROSINE
AMINO ACIDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROXY ACIDS
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PEPTIDES
PHOSPHORUS ISOTOPES
PHYTOCHROMES
PIGMENTS
PORPHYRINS
PROTEINS
RADIOISOTOPES
550201* - Biochemistry- Tracer Techniques