Moazed D, Noller H F
Sinsheimer Laboratories, University of California, Santa Cruz 95064.
Proc Natl Acad Sci U S A. 1991 May 1;88(9):3725-8. doi: 10.1073/pnas.88.9.3725.
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.
来源于酰化tRNA 3' CCA末端的寡核苷酸片段，如CACCA-(AcPhe)、UACCA-(AcLeu)和CAACCA-(fMet)，在稀疏霉素和甲醇存在的情况下能特异性结合核糖体[蒙罗，R.E.，塞尔马，M.L. & 巴斯克斯，D.（1969年）《自然》（伦敦）222, 356 - 358]。所有这三种寡核苷酸都能保护23S rRNA中一组特定的碱基免受化学探针作用：G2252、G2253、A2439、A2451、U2506和U2585。A2602的反应性增强。这些碱基与当肽基 - tRNA类似物如AcPhe - tRNA结合到核糖体P位点时被保护的大多数碱基相同，并且恰好对应于那些因tRNA的3'-CA末端被去除而保护作用消失的碱基。我们得出结论，在50S核糖体P位点观察到的tRNA与23S rRNA之间的大多数相互作用涉及tRNA保守的CCA末端。稀疏霉素可能通过稳定肽基 - CCA与23S P位点之间的相互作用来抑制蛋白质合成，从而阻止中间A/P杂交状态的形成。
