A Nuclear-Encoded Function Essential for Translation of the Chloroplast <i>psaB</i> mRNA in Chlamydomonas

Article Article scientifique Article A Nuclear-Encoded Function Essential for Translation of the Chloroplast <i>psaB</i> mRNA in Chlamydomonas eng 1997 author Stampacchia Otello 28882 author Girard-Bascou Jacqueline author Zanasco Jean-Luc 27383 author Zerges William 27937 author Bennoun Pierre author Rochaix Jean-David 25289 773-782 10.1105/tpc.9.5.773 1040-4651 http://www.plantcell.org/lookup/doi/10.1105/tpc.9.5.773 We report the analysis of a photosystem I-deficient mutant of Chlamydomonas reinhardtii, F15, that contains a mutation at the TAB1 (for translation of psaB mRNA) nuclear locus. Pulse labeling of chloroplast proteins revealed that the synthesis of the two photosystem I reaction center polypeptides PSAA and PSAB was undetectable in this mutant. The mRNA levels of these proteins were only moderately reduced, suggesting that the primary defect occurs at a step during or after translation. We constructed chimeric genes consisting of the psaA and psaB 5' untranslated region (5' UTR) fused to the aminoglycoside adenyltransferase (aadA) coding sequence, which confers spectinomycin resistance. Insertion of these genes into the chloroplast genome through biolistic transformation and analysis of their expression in the TAB1 mutant nuclear background revealed that the psaB (but not the psaA) 5' UTR is the target of the wild-type TAB1 function. This suggests that TAB1 is required for the initiation of psaB mRNA translation. The dependence of PSAA synthesis or accumulation on PSAB synthesis is strongly suggested by the identification of a suppressor mutation within the psaB 5' UTR. The suppressor specifically restores the synthesis of both proteins in the presence of the tab1-F15 mutation. The location of the suppressor mutation within a putative base-paired region near the psaB initiation codon suggests a role for TAB1 in the activation of translation of the psaB mRNA. Dewey 570 Dewey 580 Swiss National Science Foundation 31.34014.92 CH Autre UPR 9072 CNRS 43 Département de biologie moléculaire 161 45 Département des sciences végétales 163 false Plant Cell 9 5 bd94e568-7fc5-4e03-9bf2-c62d5a3c9b44 Article (Published version) Restricted 773.full.pdf 2205664 application/pdf restrictedAccess Faculté des sciences / Section de biologie / Département de biologie moléculaire Faculté des sciences / Section de biologie / Département des sciences végétales

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A Nuclear-Encoded Function Essential for Translation of the Chloroplast psaB mRNA in Chlamydomonas	Plant Cell			1997	326	0

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Zanasco, Jean-Luc