Identification of the initiation codon for the atpB gene in Chlamydomonas chloroplasts excludes translation of a precursor form of the beta subunit of the ATP synthase.
The chloroplast atpB gene of Chlamydomonas reinhardtii, which encodes the beta subunit of the ATP synthase, contains three in-frame ATGs that are candidate translation initiation codons. An earlier study revealed that the N terminus of the assembled beta subunit maps at the +2 position with respect to the second in-frame methionine codon (Fiedler et al. 1995). Using chloroplast transformation, we have examined the possibility that either of the two additional in-frame ATG codons is competent for translation initiation. We provide evidence that translation of atpB is initiated exclusively at the second ATG codon. We conclude that the beta subunit is not synthesized with an N-terminal leader before its assembly into a functional ATP synthase complex.
Rimbault
B
B
UPR-CNRS 1261, Institut de Biologie Physico-Chimique, Paris, France. Wollman@IBPC.fr
Esposito
D
D
Drapier
D
D
Choquet
Y
Y
Stern
D
D
Wollman
F A
FA
D020121:5' Untranslated Regions; D025181:ATP Synthetase Complexes; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000235:genetics*; D002736:Chloroplasts / Q000201:enzymology / Q000235:genetics; D018387:Codon, Initiator; D017931:DNA Primers / Q000235:genetics; D004792:Enzyme Precursors / Q000235:genetics; D015870:Gene Expression; D017125:Genes, Protozoan; D017930:Genes, Reporter; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D009154:Mutation; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000235:genetics*; D014176:Protein Biosynthesis; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D020121:5' Untranslated Regions; D018387:Codon, Initiator; D017931:DNA Primers; D004792:Enzyme Precursors; D009097:Multienzyme Complexes; D021122:Protein Subunits; D012333:RNA, Messenger; D016053:RNA, Protozoan; D025181:ATP Synthetase Complexes; D017856:Phosphotransferases (Phosphate Group Acceptor)