Dihydrouridine residues in bakers’ yeast transfer RNA were reductively cleaved with sodium borohydride. The amino acid acceptor activity of three species of transfer RNA and the ribosoma binding of one species of transfer RNA were determined for these modified transfer RNAs. The data indicate that the reductive cleavage of the dihydrouridine residues in these transfer RNAs has no effect upon th...

Using a novel chemical tritium derivative method, we have determined the base composition of 4S RNA isolated from an RNA tumor virus, the avian myeloblastosis virus, and from normal and neoplastic host cells. Extensive differences were detected, particularly with respect to the amount of methylated bases in the viral RNA. The viral 4S RNA, which fulfills the criteria for designation as transfer...

We are attempting to determine the nature of specific RNA-protein interactions by study of tRNA charging by homologous and heterologous enzymes. tRNAklatRNARNA3 t were prepared by phenoxyacetylation of alanyl-tRNA and separation on benzoylated DEAE-cellulose (Gillam, Blew, Warrington, von Tigerstrom & Tener, 1968). A partially purified alanyl-tRNA synthetase from yeast forms alanyl-tRNAAla tand...

The use of tRNA affinity columns for the purification of aminoacyl-tRNA synthetases was investigated. A purification method for valyl-tRNA synthetase from Bacillus stearothermophilus is described that uses two affinity columns, one containing the pure cognate tRNA, and the other containing all tRNA species except the cognate tRNA. A method for the rapid preparation of the two columns was develo...

Treatment of Escherichia coli CA265 phenylalanyl-tRNA with 3M-NaHSO3, pH6.0, at 25 degrees C resulted in modification of four bases and in the deacylation of the charged tRNAphe. The similarity of the rates of base modification and of the deacylation of the phenylalanyl-tRNA permitted the isolation of partially modified phenylalanyl-tRNAphe and partially modified deacylated tRNAphe. The sites a...

Some conditions of RNA synthesis in vitro in isolated mitochondria of Tetrahymena pyriformis were investigated. Sucrose gradient centrifugation analyses and methylated albumin-coated Kieselguhr column chromatography of the RNA synthesized in vitro demonstrate that RNA ranging from 14 S to 18 S, not transfer RNA, was synthesized. Furthermore, the RNA is hybridizable with mitochondrial DNA, and t...

RNA performs a multitude of essential cellular functions involving the maintenance, transfer, and processing of genetic information. The reason probably is twofold: (a) Life started as a prebiotic RNA World, in which RNA served as the genetic information carrier and catalyzed all chemical reactions required for its proliferation and (b) some of the RNA World functions were conserved throughout ...

Evidence for the presence of rapidly labeled short-lived RNA species, presumed to be precursors to transfer RNA (tRNA), in the silk glands of Bombyx mori is presented. These precursors, which migrate between 4S and 5S markers on acrylamide gels, can be converted in vitro into molecules indistinguishable in size from tRNA. The conversion is also catalyzed by a crude enzyme fraction isolated from...

The question whether aminoacyl-tRNA synthetases act in a stepwise or in a concerted mechanism has been investigated kinetically with the valine enzyme of Escherichia coli, which had been used in previous studies by others who concluded that the physiological mechanism is concerted. An exchange between aminoacyl-tRNA and tRNA, dependent upon AMP, was studied. PP-i inhibits this exchange complete...

Four recent studies suggest that cleavages of transfer RNAs generate products with microRNA-like features, with some evidence of function. If their regulatory functions were to be confirmed, these newly revealed RNAs would add to the expanding repertoire of small noncoding RNAs and would also provide new perspectives on the coevolution of transfer RNA and messenger RNA.