Light activates binding of membrane proteins to chloroplast RNAs in Chlamydomonas reinhardtii |
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Authors: | Zerges William Wang Shengwu Rochaix Jean-David |
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Affiliation: | (1) Biology Department, Concordia University, 1445 Maisonneuve W., Montreal, Canada, H3G 1M8;(2) Departments of Molecular Biology and Plant Biology, University of Geneva, 30 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland |
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Abstract: | Several membrane proteins were previously shown to bind to the 5 leader of the chloroplast psbC mRNA in the unicellular eukaryotic alga Chlamydomonas reinhardtii. This study showed that these proteins have affinity for AU-rich RNAs, as determined by competition experiments. In addition, their binding activities are enhanced 13–15-fold by light, and a 46 kDa protein is activated within 1–10 min. This activation could be mediated by the modulation of ADP pools by the light-dependent reactions of photosynthesis and ATP synthase because (1) two inhibitors that block ATP synthesis also prevent this activation and (2) ADP inhibits the RNA-binding activity of this protein in vitro. An inhibitor of Photosystem II diminishes this induction, suggesting that reducing potential generated by the photosynthetic electron transport chain modulates this RNA-binding activity. The RNA-binding activities of two proteins (of 46 and 47 kDa) are inhibited by Mg-protoporphyrin IX methyl ester in vitro suggesting they could be regulated by these intermediates in the chlorophyll biosynthetic pathway. |
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Keywords: | chloroplast light organelle photosynthesis RNA RNA-binding protein |
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