Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.3 (RNase T1)
 1,228 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Incubation of isolated rat liver mitochondria with radioactive amino acids resulted in the charging of tRNAs for arginine, asparagine, leucine, lysine, methionine, proline and valine. The aminoacyl-tRNAs were shown to be distinct from their cytosolic counterparts by chromatography on RPC-5. By electrophoresis on urea polyacrylamide slab gels it was found that all these mitochondrial aminoacyl-tRNAs were about 70-76 nucleotides long. The unique mitochondrial asparaginyl- and prolyl-tRNAs, not previously identified in mammalian cells, were shown to hybridize to mtDNA. Mitochondrial leucyl-tRNA separated into 3 peaks on RPC-5 and the first species was shown to be different than a combination of the other two by molecular size and partial RNase T1 digestion patterns. Each was coded by a separate gene on mtDNA as shown by partial additivity of hybridization. Separate genes for mitochondrial tRNAMetm and tRNAMetf, separated by RPC-5 chromatography, were also demonstrated. These results bring to 21 the number of individual tRNAs coded by mammalian mtDNA.
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PMID:Mammalian mitochondrial transfer RNAs: chromatographic properties, size and origin. 42 2

In order to investigate the role of nonpolar side chains in determining protein stability, we have carried out a molecular dynamics simulation study of the thermodynamics of interconverting isoleucine and valine side chains in the core of ribonuclease T1. The free energy change in the unfolded state, which we take to be fully solvated, was small and agrees qualitatively with experimental studies of alkane solvation. In the two Ile----Val mutations studied, the protein was able to relax around the smaller side chains, while in the case of the two Val----Ile mutations, the ability of the core to accommodate the extra methylene group depended on where the mutation took place. We argue that the experimentally observed decrease in stability for mutating isoleucine into valine results from a loss of favorable packing interactions of the side chain in the folded form of the protein. This supports the view that packing interactions in the folded state are an important contributor to the overall stability of the folded protein and that the core of the native protein is packed efficiently and almost completely.
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PMID:The role of packing interactions in stabilizing folded proteins. 154 26

A human genomic DNA clone hybridizing to mammalian valine tRNA(IAC) contained a cluster of three tRNA genes. Two valine tRNA genes with anticodons of AAC and CAC, encoding the major and minor cytoplasmic valine tRNA isoacceptors, respectively, and a lysine tRNA(CUU) gene were identified by Southern blot hybridization and DNA sequence analysis of a 7.1-kb region. At least nine Alu family members were interspersed throughout the 18.5-kb human DNA fragment, with three Alu elements in the intergenic region between the valine tRNA(AAC) gene and the lysine tRNA gene. Each of the five Alu family members in the sequenced region can be categorized into one of the four Alu subfamilies. The coding regions of all three tRNA genes contain characteristic internal split promoter sequences and typical RNA polymerase III termination signals in the 3'-flanking regions. The tRNA genes are accurately transcribed by RNA polymerase III in a HeLa cell extract, since the RNase T1 fingerprints of the mature-sized tRNA transcription products are consistent with the structural genes. The lysine tRNA(CUU) gene was transcribed only slightly more efficiently than the valine tRNA(CAC) gene in the homologous in vitro transcription system. Surprisingly, the valine tRNA(CAC) gene was transcribed about eightfold more efficiently than the valine tRNA(AAC) gene, implicating the presence of a modulatory element in the upstream region flanking the tRNA(CAC) gene.
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PMID:A human tRNA gene cluster encoding the major and minor valine tRNAs and a lysine tRNA. 276 31

A conformational analysis of the valine side chains of ribonuclease T1 (RNase T1) was performed using NMR spectroscopy, in particular homonuclear (1H, 1H and 13C, 13C) and heteronuclear (1H, 15N and 1H, 13C) vicinal spin-spin coupling constants as obtained from E.COSY-type NMR experiments. The coupling constants related to the chi 1 dihedral angle in valine, 3JH alpha H beta, 3JNH beta, 3JC'H beta, 3JH alpha C gamma 1, 3JH alpha C gamma 2, 3JC'C gamma 1, and 3JC'C gamma 2, were evaluated in a quantitative manner. The analysis of 3J data allowed for the stereospecific assignment of the valine methyl resonances. On the basis of various models for motional averaging of coupling constants, a fit of the torsion angles chi 1 to a set of the experimental 3J coupling constants (3JH alpha H beta, 3JNH beta, 3JC'H beta) was carried out. The resulting side-chain conformations were examined with respect to NOE distance informations. Single rotameric states emerged for Val16, Val67, Val79, and Val101, while conformational equilibria between staggered rotamers were found for Val33 and Val78. Using a different model approach, Val52 and Val89 are also likely to exhibit unimodal chi 1 angle distributions. The analysis was found to depend critically on the set of Karplus parameters used. Except for Val52 and Val78, the predominant rotamers obtained from 3J coupling informations agree with the conformation in the crystal structure of ribonuclease T1 (Martinez-Oyanedel et al., 1991).
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PMID:Conformation of valine side chains in ribonuclease T1 determined by NMR studies of homonuclear and heteronuclear 3J coupling constants. 818 Jan 70

The Escherichia coli RNase G is known as an endoribonuclease responsible for the 5'-end maturation of 16S rRNA and degradation of several specific mRNAs such as adhE and eno mRNAs. In this study, we found that an RNase G mutant derived from the MC1061 strain did not grow on a glucose minimal medium. Genetic analysis revealed that simultaneous defects of cra and ilvIH, encoding a transcriptional regulator of glycolysis/gluconeogenesis and one of isozymes of acetohydroxy acid synthase, respectively, were required for this phenomenon to occur. The results of additional experiments presented here indicate that the RNase G mutation, in combination with cra mutation, caused the increased production of pyruvic acid from glucose, which was then preferentially converted to valine due to the ilvIH mutation, resulting in depletion of isoleucine. In fact, the rng cra double mutant produced increased amount of pyruvate in the medium. These results suggest that the RNase G mutation could be applied in the breeding of producer strains of pyruvate and its derivatives such as valine.
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PMID:Increased production of pyruvic acid by Escherichia coli RNase G mutants in combination with cra mutations. 1748 40