Chihade J W, Horne D A
Department of Chemistry, Columbia University, New York, New York 10027, USA.
J Mol Recognit. 1996 Sep-Dec;9(5-6):524-7. doi: 10.1002/(sici)1099-1352(199634/12)9:5/6<524::aid-jmr295>3.0.co;2-4.
E. coli pseudouridine synthase I (PSUI) catalyzes the rearrangement of uridine residues in positions 38, 39 and 40 of tRNA transcripts to pseudouridine. These positions are located in the anticodon stem-loop of the tRNA molecule. Fourteen different E. coli tRNAs are substrates for the enzyme, whereas four other tRNAs which contain uridine in position 38 are not. Investigations were focused on the basis of enzyme differentiation between substrate and non-substrate tRNAs. Comparison of modification reactions with mutant and wild-type tRNA transcripts demonstrates that the presence of a G36 residue modulates modification by PSUI at position 38. In addition to local sequence effects, steady-state kinetic analyses suggest the existence of other recognition elements distinct from the immediate vicinity of modification.
大肠杆菌假尿苷合酶I（PSUI）催化tRNA转录本中第38、39和40位的尿苷残基重排为假尿苷。这些位置位于tRNA分子的反密码子茎环中。14种不同的大肠杆菌tRNA是该酶的底物，而另外4种在第38位含有尿苷的tRNA则不是。研究集中在该酶区分底物和非底物tRNA的基础上。对突变型和野生型tRNA转录本修饰反应的比较表明，G36残基的存在调节了PSUI对第38位的修饰。除了局部序列效应外，稳态动力学分析表明存在与修饰位点紧邻区域不同的其他识别元件。
