Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Record number 430808
Title Regulation of Photosystem II Electron transport by Bicarbonate
Author(s) Rensen, J.J.S. van
Source In: Photosynthesis: Plastid Biology, Energy Conversion and Carbon Assimilation, Advances in Photosynthesis and Respiration / Eaton-Rye, J.J., Tripathy, B.C., Sharkey, T.D., - p. 475 - 500.
DOI http://dx.doi.org/10.1007/978-94-007-1579-0_20
Department(s) Laboratory of Plant Physiology
EPS-3
Publication type Chapter in book aimed at a professional audience
Publication year 2012
Abstract In oxygenic photosynthesis, carbon dioxide is fixed by ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) and further reduced to carbohydrates. However, CO2, in the form of carbonate or bicarbonate, is also directly involved in the “light reactions” through structural and regulatory roles within Photosystem II (PS II). A notable feature is antagonistic interactions between bicarbonate (carbonate) and monovalent anions such as formate within PS II. Incubation of PS II-containing samples with formate results in the inhibition of electron flow activity, which can be restored only by the addition of bicarbonate. This “bicarbonate effect” influences molecular processes associated with both the electron acceptor and electron donor sides of PS II. The bicarbonate interaction on the acceptor side is located in the region of the primary and secondary quinones and contributes to the protonation states associated with quinol formation. At physiological pH, bicarbonate (carbonate) is a ligand to the non-heme iron and forms hydrogen bonds to several amino acids of the D1 and D2 proteins. Bicarbonate may stabilize, through conformational means, the reaction center proteins by protonation of certain amino acids near the secondary quinone electron acceptor. A possible functional role in vivo is that it controls PS II electron flow in order to ameliorate the impact of stress conditions leading to, for instance, photoinhibition or thermoinactivation. The role of bicarbonate on the donor of PS II has been the subject of renewed interest and bicarbonate has been suggested to play a role in the assembly of the Mn4Ca cluster during photoactivation. Additionally, a role as a catalytic base or proton transporter on the donor side of PS II has been proposed. However, while clear evidence for bicarbonate’s role on the acceptor side has been established, experiments designed to elucidate the putative role of bicarbonate on the donor side of PS II have not yet provided convincing evidence.
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