caa a22 4500 477136346 CHVBK 20180405111719.0 cr unu---uuuuu 170330e19970401xx s 000 0 eng 10.1023/A:1018618606857 doi (NATIONALLICENCE)springer-10.1023/A:1018618606857 The dynamic NMR structure of the TΨC-loop: Implications for the specificity of tRNA methylation [Elektronische Daten] [Letitia Yao, Thomas James, James Kealey, Daniel Santi, Uli Schmitz] tRNA (m5U54)-methyltransferase (RUMT) catalyzes the S-adenosylmethionine-dependentmethylation of uridine-54 in the TΨC-loop of all transfer RNAs in E. coli to form the 54-ribosylthymine residue. However, in all tRNA structures, residue 54 is completely buried andthe question arises as to how RUMT gains access to the methylation site. A 17-mer RNAhairpin consisting of nucleotides 49-65 of the TΨ-loop is a substrate for RUMT.Homonuclear NMR methods in conjunction with restrained molecular dynamics (MD)methods were used to determine the solution structure of the 17-mer T-arm fragment. Theloop of the hairpin exhibits enhanced flexibility which renders the conventional NMR averagestructure less useful compared to the more commonly found situation where a molecule existsin predominantly one major conformation. However, when resorting to softer refinementmethods such as MD with time-averaged restraints, the conflicting restraints in the loop canbe satisfied much better. The dynamic structure of the T-arm is represented as an ensembleof 10 time-clusters. In all of these, U54 is completely exposed. The flexibility of the TΨ-loop in solution in conjunction with extensive binding studies of RUMT with the TΨC-loop and tRNA suggest that the specificity of the RUMT/tRNA recognition is associated withtRNA tertiary structure elements. For the methylation, RUMT would simply have to breakthe tertiary interactions between the D- and T-loops, leading to a melting of the T-armstructure and making U54 available for methylation. Kluwer Academic Publishers, 1997 Dynamic NMR refinement nationallicence MD with time-averaged restraints nationallicence TΨC-loop nationallicence RUMT nationallicence RNA/protein recognition nationallicence Yao Letitia Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut James Thomas Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut Kealey James Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut Santi Daniel Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut Schmitz Uli Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut Journal of Biomolecular NMR Kluwer Academic Publishers 9/3(1997-04-01), 229-244 0925-2738 9:3<229 1997 9 10858 https://doi.org/10.1023/A:1018618606857 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1018618606857 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Yao Letitia Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut NATIONALLICENCE 700 1- James Thomas Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut NATIONALLICENCE 700 1- Kealey James Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut NATIONALLICENCE 700 1- Santi Daniel Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut NATIONALLICENCE 700 1- Schmitz Uli Department of Pharmaceutical Chemistry, University of California, 94143-0446, San Francisco, CA, U.S.A aut NATIONALLICENCE 773 0- Journal of Biomolecular NMR Kluwer Academic Publishers 9/3(1997-04-01), 229-244 0925-2738 9:3<229 1997 9 10858 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer