Dynamic flexibility in the light reactions of photosynthesis governed by both electron and proton transfer reactions.
Plant photosynthesis performs the remarkable feat of converting light energy into usable chemical forms, which involves taming highly reactive intermediates without harming plant cells. This requires an apparatus that is not only efficient and robust but also flexible in its responses to changing environmental conditions. It also requires that the output of the energy-storing reactions be matched with the demands of metabolism. This article addresses the mechanisms by which this flexibility is achieved for short-term environmental changes. We argue that chloroplasts need two types of flexible mechanisms: one for modulating the output ratio of ATP:NADPH, which involves cyclic electron flux around photosystem I; and another for changing the regulatory sensitivity of the light-harvesting antenna to electron (and proton) flow.
Kramer
David M
DM
Institute of Biological Chemistry, Washington State University, Pullman, WA 99164, USA. dkramer@wsu.edu
Avenson
Thomas J
TJ
Edwards
Gerald E
GE
D000255:Adenosine Triphosphate / Q000378:metabolism; D001692:Biological Transport / Q000528:radiation effects; D004579:Electron Transport / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology / Q000528:radiation effects*; D045331:Photosystem I Protein Complex / Q000378:metabolism; D010944:Plants / Q000378:metabolism / Q000528:radiation effects*; D017494:Proton Pumps / Q000378:metabolism*
D045342:Light-Harvesting Protein Complexes; D045331:Photosystem I Protein Complex; D017494:Proton Pumps; D009249:NADP; D000255:Adenosine Triphosphate