Plastoquinone redox control of chloroplast thylakoid protein phosphorylation and distribution of excitation energy between photosystems: discovery, background, implications

Chloroplast thylakoid protein phosphorylation was discovered, and the most conspicuous phosphoproteins identified, by John Bennett at Warwick University. His initial findings were published in 1977. The phosphoproteins included apoproteins of chloroplast light harvesting complex II. Thylakoid protein phosphorylation was shown to influence distribution of excitation energy between Photosystems I and II in 1979, during a visit by Bennett to the laboratory of Charles J. Arntzen at the University of Illinois at Urbana-Champaign. That work was published by Bennett, Katherine E. Steinback and Arntzen in 1980. Control of both protein phosphorylation and excitation energy distribution by the redox state of the plastoquinone pool was first established in 1980 during the author's visit to Arntzen's laboratory. The experiments were prompted by the realization that coupling between redox state of an inter-photosystem electron carrier and excitation energy distribution provides a concrete mechanism for adaptations known as state transitions. This work was published by Allen, Bennett, Steinback, and Arntzen in 1981. This discovery and its background are discussed, together with some implications for photosynthesis and for research generally. This minireview is a personal account of the Urbana-Warwick and related collaborations in 1979-83: it includes impressions, conjectures, and acknowledgements for which the author is solely responsible.