Glycine transfer RNA of Escherichia coli. II. Impaired GGA-recognition in strains containing a genetically altered transfer RNA; reversal by a secondary suppressor mutation.

摘要: Abstract The glycine-specific tRNA from Escherichia coli is separable into three components (tRNAIGly, tRNAIIGly and tRNAIIIGly) by chromatography over BD-ellulose. ‡ Triplet binding studies reveal that tRNAIGly recognizes predominantly GpGpG, both GpGpG GpGpA, tRNAIIIGly GpGpU GpGpC. Strains carrying a suppressor (glyTsu) of the trpA36 mutation (Gly → Arg, GGA AGA) lack functional and, as result, exhibit severe pleiotropic effects. As expected, [14C]glycyl-tRNA glyTsu strains to ribosomes only weakly stimulated GpGpA (8% control), while in presence GpGpC relatively normal. On other hand, suppressed (glyUsu) lacking do not show these adverse effects, displays nearly normal codon recognition pattern. effects seen are reversed either (a) glyT+ gene same organism, or (b) secondary mutations (ins) unlinked glyT region. GpGpA-stimulated ins partially restored Transfer RNA contains new tRNAGly species (tRNAIIIGly), easily detectable BD-cellulose chromatography. This tRNAIIIGly, binds but results indicate formed genetically induced alteration portion tRNAIIIGly. It seems likely GGU/C GGA/G change redundant species, thus relieving pleiotropy loss tRNAIIGly.