Site-directed mutagenesis in photosystem II of the cyanobacterium Synechocystis sp. PCC 6803: Donor D is a tryosine residue in the D2 protein

Journal Article · Tue Nov 01 00:00:00 EST 1988 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.85.22.8477· OSTI ID:5563304

Vermaas, W F.J.; Rutherford, A W; Hansson, O ^[1]

---

1. Arizona State Univ., Tempe (USA)

The chemical nature of electron donor(s) in photosystem II in photosynthetic membranes was analyzed by site-directed mutagenesis of the gene encoding the protein D2 of the photosystem II reaction center. Mutation of the Try-160 residue of the D2 protein into phenylalanine results in the disappearance of the electron paramagnetic resonance signal II{sub s} originating from D{sup +}, the oxidized form of the slow photosystem II electron donor D. Signal II{sub s} is still present if a neighboring residue in D2, Met-159, is mutated into arginine. Both mutants have normal rereduction kinetics of the oxidized primary electron donor, P680{sup +}, in octyl glucoside-extracted thylakoids, indicating that D is not directly involved in P680{sup +} reduction. However, overall photosystem II activity appears to be impaired in the Try-160-Phe mutant: photosystem II-dependent growth of this mutant is slowed down by a factor of 3-4, whereas photoheterotrophic growth rates in wild type and mutant are essentially identical. Binding studies of diuron, a photosystem II herbicide, show that there is no appreciable decrease in the number of photosystem II centers in the Tyr-160-Phe mutant. The decrease in photosystem II activity in this mutant may be interpreted to indicate a role of D in photoactivation, rather than one as an important redox intermediate in the photosynthetic electron-transport chain.

• DOE Contract Number: FG02-88ER13969
• OSTI ID: 5563304
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 85:22; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
CYANOBACTERIA
MUTAGENESIS
HERBICIDES
BIOLOGICAL EFFECTS
PHOTOSYNTHETIC REACTION CENTERS
BIOPHYSICS
ARGININE
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
GENES
OXIDATION
PHENYLALANINE
PHOTOSYNTHETIC MEMBRANES
TYROSINE
WATER
AMINO ACIDS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
HYDROGEN COMPOUNDS
HYDROXY ACIDS
MAGNETIC RESONANCE
MEMBRANES
MICROORGANISMS
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PESTICIDES
RESONANCE
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)