Sites of interaction of the CCA end of peptidyl-tRNA with 23S rRNA.
Oligonucleotide fragments derived from the 3' CCA terminus of acylated tRNA, such as CACCA-(AcPhe), UACCA-(AcLeu), and CAACCA-(fMet), bind specifically to ribosomes in the presence of sparsomycin and methanol [Monro, R. E., Celma, M. L. & Vazquez, D. (1969) Nature (London) 222, 356-358]. All three oligonucleotides protect a characteristic set of bases in 23S rRNA from chemical probes: G2252, G2253, A2439, A2451, U2506, and U2585. A2602 shows enhanced reactivity. These account for most of the same bases that are protected when peptidyl-tRNA analogues such as AcPhe-tRNA are bound to the ribosomal P site, and correspond precisely to those bases whose protection is abolished by removal of the 3'-CA end of tRNA. We conclude that most of the observed interactions between tRNA and 23S rRNA in the 50S ribosomal P site involve the conserved CCA terminus of tRNA. Sparsomycin may inhibit protein synthesis by stabilizing interaction between the peptidyl-CCA and the 23S P site, preventing formation of the intermediate A/P hybrid state.
Moazed
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Sinsheimer Laboratories, University of California, Santa Cruz 95064.
Noller
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D001483:Base Sequence; D001665:Binding Sites; D004926:Escherichia coli; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D014176:Protein Biosynthesis; D012338:RNA, Ribosomal, 23S / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D013033:Sparsomycin / Q000494:pharmacology; D013329:Structure-Activity Relationship
D009841:Oligonucleotides; D012338:RNA, Ribosomal, 23S; D013033:Sparsomycin; D012343:RNA, Transfer