Chloroplast ribosomal protein S7 of Chlamydomonas binds to chloroplast mRNA leader sequences and may be involved in translation initiation.
Certain mutations isolated in the 5' untranslated region (5'UTR) of the chloroplast rps7 gene in Chlamydomonas reduce expression of reporter genes. Second site suppressors in this 5'UTR sequence restore reporter expression. 5'UTR sequences with the original mutations fail to bind a 20-kD protein, one of five proteins that bind to leaders of several chloroplast genes. However, 5'UTRs from suppressed mutants restore binding to this protein but do not bind a 47-kD protein present on the wild type and the original mutant 5'UTRs. The 20-kD protein was shown to be the S7 protein of the chloroplast ribosomal small subunit encoded by rps7, whereas the 47-kD protein was shown to be RB47, a poly(A) binding protein. Our data are consistent with the hypothesis that the S7 protein plays either a general or a specific regulatory role in translation initiation in the chloroplast.
Fargo
D C
DC
Developmental, Cell and Molecular Biology Group, Duke University LSRC Building, Box 91000 Research Drive, Durham, North Carolina 27708, USA. dcf2@duke.edu
Boynton
J E
JE
Gillham
N W
NW
D020121:5' Untranslated Regions; D000818:Animals; D001483:Base Sequence; D002696:Chlamydomonas / Q000378:metabolism*; D002736:Chloroplasts / Q000235:genetics*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D014176:Protein Biosynthesis / Q000502:physiology*; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics*; D011994:Recombinant Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism* / Q000502:physiology
D020121:5' Untranslated Regions; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012269:Ribosomal Proteins; C037442:ribosomal protein S7