title: Correlation between the stability of tRNA tertiary structure and the catalytic efficiency of a tRNA-modifying enzyme, archaeal tRNA-guanine transglycosylase.
abstract: In many archaeal tRNAs, archaeosine is found at position 15. During archaeosine biosynthesis, archaeal tRNA-guanine transglycosylase (ArcTGT) first replaces the guanine base at position 15 with 7-cyano-7-deazaguanine (preQ0). In this study, we investigated whether modified nucleosides in tRNA substrates would affect ArcTGT incorporation of preQ0. We prepared a series of hypomodified tRNAs(Ser)(GGA) from Escherichia coli strains lacking each tRNA-modifying enzyme. Measurement of ArcTGT kinetic parameters with the various tRNAs(Ser)(GGA) as substrates showed that the Km decreased due to the lack of modified nucleosides. The tRNAs(Ser)(GGA) melting profiles resulted in experimental evidence showing that each modified nucleoside in tRNA(Ser)(GGA) enhanced tRNA stability. Furthermore, the ArcTGT K(m) strongly correlated with the melting temperature (T(m)), suggesting that the unstable tRNA containing fewer modified nucleosides served as a better ArcTGT substrate. These results show that preQ0 incorporation into tRNA by ArcTGT takes place early in the archaeal tRNA modification process.
authors.affiliation: Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Nomura
authors.affiliation: Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ohno
authors.affiliation: Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Nishikawa
authors.affiliation: Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu, 501-1193, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yokogawa
mesh_terms: D001105:Archaea / Q000201:enzymology / Q000235:genetics; D001483:Base Sequence; D055162:Biocatalysis; D004926:Escherichia coli / Q000378:metabolism; D006147:Guanine / Q000378:metabolism; D007700:Kinetics; D017020:Methanosarcina / Q000201:enzymology*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010430:Pentosyltransferases / Q000378:metabolism*; D020871:RNA Stability / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D044366:Transition Temperature
chemical_list: D012333:RNA, Messenger; D006147:Guanine; D012343:RNA, Transfer; D010430:Pentosyltransferases; C020837:queuine tRNA-ribosyltransferase