Membrane protein damage and repair: selective loss of a quinone-protein function in chloroplast membranes. [Chlamydomonas]
A loss of electron transport capacity in chloroplast membranes was induced by high-light intensities (photoinhibition). The primary site of inhibition was at the reducing side of photosystem II (PSII) with little damage to the oxidizing side or to the reaction center core of PSII. Addition of herbicides (atrazine or diuron) partially protected the membrane from photoinhibition; these compounds displace the bound plastoquinone (designated as Q/sub B/), which functions as the secondary electron acceptor on the reducing side of PSII. Loss of function of the 32-kilodalton Q/sub B/ apoprotein was demonstrated by a loss of binding sites for (/sup 14/C)atraazine. We suggest that quinone anions, which may interact with molecular oxygen to produce an oxygen radical, selectively damage the apoprotein of the secondary acceptor of PSII, thus rendering it inactive and thereby blocking photosynthetic electron flow under conditions of high photon flux densities. 21 references, 4 figures, 2 tables.
- Research Organization:
- Michigan State Univ., East Lansing, MI (United States)
- DOE Contract Number:
- AC02-76ER01338
- OSTI ID:
- 5888120
- Journal Information:
- Proc. Natl. Acad. Sci. U.S.A.; (United States), Vol. 81:13
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CELL MEMBRANES
DAMAGE
CHLAMYDOMONAS
PHOTOSYNTHETIC REACTION CENTERS
CHLOROPLASTS
PHOTOSENSITIVITY
INACTIVATION
BIOLOGICAL EFFECTS
BIOLOGICAL REPAIR
CARBON 14 COMPOUNDS
CHEMICAL BONDS
PHOTOSYNTHESIS
PROTEINS
TRACER TECHNIQUES
VISIBLE RADIATION
ALGAE
BIOLOGICAL RECOVERY
CELL CONSTITUENTS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MEMBRANES
MICROORGANISMS
ORGANIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PLANTS
RADIATIONS
RECOVERY
REPAIR
SENSITIVITY
SYNTHESIS
UNICELLULAR ALGAE
560302* - Chemicals Metabolism & Toxicology- Microorganisms- (-1987)