5-Carboxymethyluridine, a novel nucleoside derived from yeast and wheat embryo transfer ribonucleates

Abstract

A carboxyl-containing nucleoside, 5-carboxymethyluridine, has been isolated from the transfer ribonucleates of bakers' yeast, brewers' yeast, and wheat embryo. The 2'-and 3'-nucleotides of 5-carboxymethyluridine were isolated from alkali hydrolysates of the purified transfer ribonucleate preparations. A phosphodiesterase hydrolysate of wheat embryo transfer ribonucleates was examined for the presence of 5-carboxymethyluridine 5'-phosphate, but none could be detected. However, after alkali treatment of the 5'-nucleotides produced by the action of phosphodiesterase on wheat embryo transfer ribonucleates, a compound having the properties of the 5'-nucleotide of 5-carboxyinethyluridine was isolated. This observation suggests A lkali hydrolysis of tRNA or rRNA releases nucleosides (N) and nucleoside 2'(3 '),5 '-bisphosphates (pNp) from chain termini, and nucleoside 2'(3 ')-monophosphates (Np) and alkali-stable dinucleotides (NmpNp)' from internal positions of the ribonucleate chains. By ion-exchange chromatography on DEAEcellulose columns, using urea-containing eluents (Tomlinson and Tener, 1963), these four types of product can be resolved from one another according to their different net charges at pH 7.8 (N, 0; Np, -2; NmpNp, -3; and pNp, -4). Stepwise elution with urea-containing eluents of increasing ionic strength cleanly resolves the

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

“…262 (pH l ) , 264 (pH 7), and 289 (pH 13); Ami,, 232 (pH l ) , 234 (pH 7), 245 (pH 13)) of the base liberated by acid hydrolysis of cm5Um were the same as those of synthetic 5-carboxymethyluracil (Gray and Lane, 1968). The two compounds were also chromatographically and electrophoretically identical ( Table V).…”

“…The ultraviolet absorption spectra of cmSUm ( Figure 2A) were essentially identical with those of cmsU (Gray and Lane, 1968). In particular, both cmSU and cm5Um displayed the slight but distinctive spectral shift, which is associated with the ionization of the carboxyl function (Kwong and Lane, 1970) between acidic and neutral pH values.…”

“…Uridine (U) and 02,-methyluridine (Um) were commercial products (Calbiochem and ICN Pharmaceuticals, respectively). 5-Carboxymethyluridine (from yeast transfer RNA) and 5-carboxymethyluracil (cm5u) were prepared by published methods (Gray and Lane, 1968). The amide and methyl ester derivatives of cm5U, synthesized by the procedures of Fissekis and Sweet (1970), were kindly provided by Dr.J.…”

“…Among the hypermodified nucleosides occupying the "Wobble" position of the anticodon sequence are derivatives of 5-carboxymethyluridine (cm5U, l)1, a carboxyl-containing nucleoside originally isolated as the 2'(3/)nucleotide from alkaline hydrolysates of yeast and wheat embryo transfer RNA Lane, 1967, 1968). In native tRNA, this nucleoside is present primarily (if not exclusively) in a carboxyl-blocked form (Gray and Lane, 1968), and both the methyl ester (5-carbomethoxymethyluridine, mcm5U, 2) (Tumaitis ) and the amide (5-carbamoylmethyluridine, ncm5U, 3) (Dunn and Trigg, 1975) derivatives of cm5U have been identified as constituents of tRNA. The occurrence of mcm5U in the "Wobble" position in brewer's yeast tRN AArg3 has recently been demonstrated (Kuntzel et al, 1975), and there is evidence that the same compound is present in other species of yeast tRNA (Kennedy and Lane, 1975).…”

Aminoacyl nucleosides. VII. N-(purin-6-ylcarbamoyl)threonine. A new component of transfer ribonucleic acid

“…A precedent exists for the esterification of other components of tRNA that contain carboxyl groups. 2-Thio-5-carboxymethyluridine is isolated as the methyl ester (Baczynskyj et al, 1968) and 5carboxymethyluridine isolated by Gray and Lane (1968) appears to exist in the tRNA in an esterified form.…”