ADP-dependent phosphorylation regulates RNA-binding in vitro: implications in light-modulated translation.
Light-regulated translation of chloroplastic mRNAs in the green alga Chlamydomonas reinhardtii requires nuclear encoded factors that interact with the 5'-untranslated region (5'-UTR) of specific mRNAs to enhance their translation. We have previously identified and characterized a set of proteins that bind specifically to the 5'-UTR of the chloroplastic psbA mRNA. Accumulation of these proteins is similar in dark- and light-grown cells, whereas their binding activity is enhanced during growth in the light. We have identified a serine/threonine protein phosphotransferase, associated with the psbA mRNA-binding complex, that utilizes the beta-phosphate of ADP to phosphorylate and inactivate psbA mRNA-binding in vitro. The inactivation of mRNA-binding in vitro is initiated at high ADP levels, levels that are attained in vivo only in dark-grown chloroplasts. These data suggest that the translation of psbA mRNA is attenuated by phosphorylation of the mRNA-binding protein complex in response to a rise in the stromal concentration of ADP upon transfer of cells to dark.
Danon
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A
Department of Cell Biology, Scripps Research Institute, La Jolla, CA 92037.
Mayfield
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SP
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D007438:Introns; D008027:Light; D010766:Phosphorylation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000528:radiation effects*; D011494:Protein Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism
D001426:Bacterial Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011494:Protein Kinases