The tRNA-(m5U54)-methyltransferase of Escherichia coli is present in two forms in vivo, one of which is present as bound to tRNA and to a 3'-end fragment of 16 S rRNA.
The enzyme tRNA-(m5U54)-methyltransferase (EC 2.1.1.35) of Escherichia coli catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to uridine in position 54 of the T psi-loop of all E. coli tRNA species, forming 5-methyluridine (m5U). In vivo, this enzyme is present both as a native polypeptide of 42 kDa and as a TrmA.RNA complex. The TrmA.RNA complex is not dissociated during strong denaturing conditions such as boiling in 8 M urea or 6 M guanidine HCl, consisting with that the RNA is covalently bound to the protein. After sequencing and Southern blot analyses, the RNA was identified to be a subset of undermodified tRNA species as well as the 3' terminus of 16 S rRNA. However, the complex is not associated with the ribosome and the covalently bound RNA does not affect the tRNA methylating activity of the enzyme.
Gustafsson
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Department of Microbiology, University of Umeå, Sweden.
Björk
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D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D002499:Centrifugation, Density Gradient; D002852:Chromatography, Ion Exchange; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D008961:Models, Structural; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009876:Operon; D011485:Protein Binding; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D012436:S-Adenosylmethionine / Q000494:pharmacology; D012359:tRNA Methyltransferases / Q000302:isolation & purification / Q000378:metabolism*
D012336:RNA, Ribosomal, 16S; D012436:S-Adenosylmethionine; D012343:RNA, Transfer; D012359:tRNA Methyltransferases; C022769:tRNA(uracil-5)-methyltransferase