Transfer RNA from super-suppressor mutants of Saccharomyces cerevisiae cannot suppress an amber mutation in vitro in an E. coli protein synthesizing system. It is tentatively concluded that the yeast amber suppressor does not contain a transfer RNA altered in the anticodon.

1. tRNA of Bacillus subtilis was found to be variably contaminated with membrane teichoic acid. 2. Samples with high contents of teichoic acid showed no accepting activity for tRNA(Phe) and tRNA(Tyr). 3. Removal of teichoic acid restored accepting activity and fractions containing teichoic acid, separated on Sephadex G-150, inhibited the charging of tRNA(Tyr). 4. The presence of teichoic acid d...

Edman degradations were performed on the pentapeptide bridges of peptidoglycans which were biosynthesized in vitro by using six different species of seryl-transfer ribonucleic acid (tRNA). The ratio of glycine to serine in each of the five bridge positions varied with the concentration of crude glycyl-tRNA contained in the reaction mixtures, and serine appeared to be incorporated in a random ma...

The shape of the time curve for the aminoacylation of tRNA has been investigated using five different amino acid:tRNA ligases. Four of these enzymes showed a lag in the time curve during the early phase of the first catalytic turnover of the enzyme. In each case, the lag period could be abolished by preincubating the ligase with amino acid, ATP, and Mg2+ under conditions known to give an aminoa...

The organization of seven genes located at about 38 min on the genetic map of Escherichia coli was examined; these genes included pheS and pheT, which code for the alpha and beta subunits of phenylalanyl-transfer ribonucleic acid synthetase, and thrS, the structural gene for threonyl-transfer ribonucleic acid synthetase. Deletion mutants were isolated from an F-prime-containing merodiploid stra...

Modified nucleosides in natural RNA molecules are essential for their functions. Non-natural nucleoside analogues have been introduced into RNA to manipulate its structure and function. We have recently developed a new strategy for the in situ modification of RNA based on the functionality transfer reaction between an oligodeoxynucleotide probe and an RNA substrate. 2'-Deoxy-6-thioguanosine (6-...

Transfer ribonucleic acid (tRNA) that is deficient in methyl groups may be detected in logarithmically growing Saccharomyces cerevisiae. The amount of methyl-deficient tRNA is not constant throughout the logarithmic phase, but is maximal about one generation before the onset of the late growth phase. During this latter phase, the tRNA is fully methylated. The methyl-deficient tRNA is present du...