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The balancing act: redox poise and signalling JF Allen, J Forsberg

Summary: PL-004
The balancing act: redox poise and signalling
JF Allen, J Forsberg
Plant Biochemistry, Lund University, Box 117, SE-221 00 Lund, Sweden
john.allen@plantbio.lu.se, jens.forsberg@plantbio.lu.se, fax+46 46 2224009
Keywords: state transitions, photosystem stoichiometry, redox signalling, molecular
recognition, two-component systems
Biological electron transfer requires continual monitoring and adjustment of redox state
of electron carriers. Maintenance of optimal efficiency is exemplified in photosynthesis
by light-state transitions and by adjustment of photosystem stoichiometry.
Adjustment of relative and absolute light-harvesting antenna size and density of
photosynthetic units takes place in response to changing light quality or quantity, and in
response to altered metabolic demand for ATP relative to reducing power. Plastoquinone
redox state governs both antenna size and the relative rates of synthesis and breakdown of
the two photosystems. Plastoquinone and its binding sites in the cytochrome b6-f complex
and in photosystem II are located between the two photosystems, and the redox signals
emanating from this point in the photosynthetic electron transport chain form part of
homeostatic negative feedback loops that operate at a number of levels of gene
expression. These redox signalling pathways serve to maintain an optimal redox state of


Source: Allen, John F. - School of Biological and Chemical Sciences, Queen Mary, University of London


Collections: Renewable Energy; Biology and Medicine