The coding properties of methyl-deficient leucyl-transfer RNA.
Escherichia coli 58-161, a methionine auxotroph with "relaxed control", synthesizes methyl-deficient transfer RNA (tRNA) when subjected to methionine deprivation. Whereas [14C]leucyl-tRNA from normally grown bacteria fractionates into two peaks (I and II) on methylated albumin-kieselguhr columns, methyl-deficient [14C]leucyl-tRNA shows an additional component (peak III). A ribosome-binding assay shows a marked difference in the coding response to poly UC and poly UG between normal and methyl-deficient [14C]leucyl-tRNA. Compared to normal E. coli 58-161 [14C]leucyl-tRNA, the leucine-tRNA isolated from methionine-deprived cells, manifests a twofold increase in poly UG response and a fivefold increase in poly UC response. Chromatography on methylated albumin-kieselguhr columns localized the increase in poly UG reactive tRNA to peak II. The chromatographic component of leucyl-tRNA characteristic of methyl-deficiency (peak III) responded exclusively to poly UC. These results are discussed in terms of a possible requirement for methylated bases in tRNA for specific codon recognition.
Capra
J D
JD
Laboratory of Biochemistry, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20014, USA.
Peterkofsky
A
A
D003062:Codon / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005815:Genetic Code; D008274:Magnesium / Q000378:metabolism; D008715:Methionine / Q000378:metabolism*; D008745:Methylation; D011066:Poly C / Q000235:genetics / Q000378:metabolism; D011072:Poly U / Q000235:genetics / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism
D003062:Codon; D012346:RNA, Transfer, Amino Acyl; D011072:Poly U; D011066:Poly C; D008715:Methionine; D008274:Magnesium