Unassembled subunits of the photosynthetic oxygen-evolving complex present in the thylakoid lumen are long-lived and assembly-competent.
Physiologically healthy pea chloroplasts contain unassembled, soluble subunits of the oxygen-evolving complex in the thylakoid lumen. We report that the lifetimes of two of these subunits, both on and off the membrane, exceed 8 h in vitro. We also demonstrate that each of the subunits present in the thylakoid lumen is competent for assembly into the membrane-bound complex. These data are consistent with the postulate that the soluble lumen-resident subunits play a role in photosystem II homeostasis. We also demonstrate that the reconstitution of the 33 kDa subunit is inhibited by extremely low concentrations of Triton X-100, suggesting that hydrophobic interactions are involved in the binding of this subunit to the photosystem II reaction center.
Hashimoto
A
A
Section of Plant Biology, University of California, Davis 95616, USA.
Yamamoto
Y
Y
Theg
S M
SM
D002458:Cell Fractionation; D002736:Chloroplasts / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D007700:Kinetics; D046911:Macromolecular Substances; D015388:Organelles / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D018532:Pisum sativum / Q000378:metabolism*; D010788:Photosynthesis; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D013997:Time Factors
D046911:Macromolecular Substances; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010100:Oxygen