Cell-free enzymic esterification of 5-carboxymethyluridine residues in bulk yeast transfer RNA

Complete nuclear magnetic resonance signal assignments and initial structural studies of [13C]methyl-enriched transfer ribonucleic acid

“…The unesterified nucleoside has between shown to occur in approximately 10% of the published E. coli tRNA sequences (Table I). However, it is highly likely that esterification occurs in vivo with methionine as the methyl donor (Kwong & Lane, 1970) and can be lost during isolation of the tRNA as has been shown for a similar nucleoside in yeast tRNA (Kuntzel et al, 1975;Bronskill et al, 1972). Chemical shifts for similar methyl esters occur in the range of 51.0-51.3 ppm (Stothers, 1972).…”

Structural analysis of O2'-methyl-5-carbamoylmethyluridine, a newly discovered constituent of yeast transfer RNA

“…15, NO. 14, side chains of mcm5U and s2cm5U in yeast tRNA are known to be derived from S-adenosylmethionine both in vivo (Tumaitis and Lane, 1970; Kwong and Lane, 1970) and in vitro (Bronskill et al, 1972;Kennedy and Lane, 1975;Kuntzel et al, 1975). It is not yet known whether there exists a comparable enzyme system capable of carrying out the amidation of the carboxyl function of cm5U residues in tRNA, and which, therefore, might be involved in the biosynthesis of ncm5U and ncm5Um.…”

Regulation of tRNA

“…All modification reactions seem to occur after the polynudeotide chain has been synthesized. Several reports have described the isolation and characterization of tRNA-modifying enzymes that catalyze the following reactions on the polynudeotide level: methylation (76-82, and reviews 72, 83); thiolation (84)(85)(86); isopentenylation (87, 88, review 2-thiomethyl-6-isopentenyl adenosine (2MSiPA) formation (80); pseudouridine (~b) formation (47); and esterification of 5-carboxymethyluridine (90). In labeling studies show that in both E. coli (91)(92)(93) and rat liver (93) threonine is precursor of the threonine moiety of N-(purin-6-yl carbamoyl) threonine residues.…”