Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mutants of Pseudomonas aeruginosa PAO deficient in their utilization of DL-valine have been found to have lost their capacity to utilize DL-alanine and L-proline. Use of conjugal and transductional mediated gene transfers have established the chromosomal location of this gene and also its pleotropic function in the induction of the D-amino acid oxidase, involved in the oxidative utilization of DL-valine, DL-alanine and L-proline. These point mutations are clustered in a single locus designated as Val D and mapped around the 19th minute on the chromosome.
Mol Gen Genet 1978 Aug 04
PMID:Mapping of the locus involved in the catabolic oxidation of D-amino acids in Pseudomonas aeruginosa PAO. 3 39

The pH-dependence of the reduction rate of ferricytochrome C by intact and chemically modified oxymyoglobins has been studied. The modification was performed with respect to histidine residues and alpha-aminogroup of N-terminal valine. Two histidine residues of myoglobin, His A10 and His GH1, are shown to take part in the realization of the "active" contact between the molecules in the course of the reaction. The deprotonation of the first residue contributes to the acceleration and that of the second to the reduction of the reaction. The found orientation of the Mb molecules in the "active complex" implies that at any orientation of cytochrome C the distance between the haemes of the both molecules should be more than 30 A. This makes highly probable that a structure-dependent mechanism of electron transfer in the system under study can be proposed.
Mol Biol (Mosk)
PMID:[Electron transfer to hemoproteins. II. pH-dependence of the reduction rate of ferricytochrome c by oxymyoglobin]. 3 34

Mutants of an aminopterin-resistant strain of pneumococcus possessing four different suppressor genes have been isolated after mutagenesis with 5-BUdR. The suppressed strains exhibit a partial revertant phenotype since the parental aminopterin resistance remained unchanged but the associated sensitivity to an excess concentration of the branched chain amino acids L-isoleucine, L-valine and L-leucine was diminished almost to the level of the wild-type strain C13. The suppressor mutations had therefore dissociated the two properties associated with a mutation in the amiA cistron, namely aminopterin resistance and isoleucine sensitivity. The suppressor genes reduced the sensitivity to isoleucine of a number of amiA mutants, but had no effect on the level of resistance to a number of unrelated genes conferring resistance to other antibacterial substances. The suppressor mutations themselves did not confer resistance to aminopterin. Mapping of the suppressor mutations by recombination analysis and by clonal analysis showed them to be intragenic lying in the region near to the amiA-r19, amiA-r23, amiA-r17 loci.
Mol Gen Genet 1979 Jul 24
PMID:Suppressor mutations causing partial reversion in the amiA region of Pneumococcus. 3 21

1. The metabolic responses to an oral glucose tolerance test (100 g) and an intravenous insulin provocation test (0-1 i.u./kg) were studied in nine control subjects and nine patients with Huntington's chorea. 2. Plasma glucose responses to these stimuli were identical in both groups. 3. High fasting concentrations of non-esterified fatty acid (NEFA) were recorded in the choreic patients when compared with control subjects. This difference was maintained under hypoglycaemic conditions. However, during hyperglycaemia the differences in NEFA concentrations between the groups was abolished. 4. Total plasma tryptophan concentrations were equal in the two groups. Free plasma tryptophan, however, was markedly reduced in the choreic group, and this appeared to be a result of a disturbed relationship between free tryptophan and NEFA concentrations. The abnormalities in free tryptophan values were sensitive to plasma glucose concentrations, as hyperglycaemic conditions markedly reduced the differences between the choreic and control group. 5. Patients with Huntington's chorea showed reduced fasting plasma concentrations of leucine, isoleucine and valine.
Clin Sci Mol Med 1977 Mar
PMID:Plasma glucose, non-esterified fatty acids and amino acids in Huntington's chorea. 13 25

A hybridization assay using Escherichia coli K-12 DNA isolated from the specialized transducing bacteriophage gammaCI857St68h80 dilv was used to examine the rate of synthesis of the messenger RNA's (mRNA) derived from the isoleucine-valine (ilv) gene cluster of Salmonella typhimurium. In all cases examined, changes in ilv enzyme levels could be correlated with changes in the rate of synthesis of ilv mRNA. Several well characterized regulatory mutants of S. typhimurium had rates of synthesis of ilv mRNA 3 to 8-fold higher than the repressed wild-type strain. The increased rates of ilv mRNA synthesis found in a hisT strain as well as in isoleucyl-and leucyl-tRNA SYNTHETASE MUTANTS, STRONGLY SUGGESTS A ROLE FOR BRANCHED-CHAIN AMINOACYL-TRNA's in transcriptional control.
Mol Gen Genet 1977 Mar 07
PMID:Detection of messenger RNA from the isoleucine--valine operons of Salmonella typhimurium by heterologous DNA-RNA hybridization: involvement of transfer RNA in transcriptional repression. 32 61

We studied the production of the ilvG gene product, the valine resistant acetolactate synthase isoenzyme II, in an ilvO+ G+ ilvB ilvHI derivative of Escherichia coli K-12. This strain contains mutations in the structural genes for the valine sensitive acetolactate synthase isoenzymes I and III. We find that the ilvG gene is not expressed in this strain when gworn with either isoleucine and valine or with isoleucine, leucine and valine, or when limited for either isoleucine or valine. Since we previously found that the ilvG gene is expressed in an ilvO603 containing strain (Favre et al., 1976), we presume that the mechanism by which E. coli K-12 regulates the ilv gene cluster is responsible for the lack of ilvG expression in the ilvO+ strain. The valine sensitivity of E. Coli K-12 is a consequence of this regulatory pattern.
Mol Gen Genet 1977 Nov 04
PMID:Growth inhibition of Escherichia coli K-12 by L-valine: a consequence of a regulatory pattern. 34 Aug 87

We describe the regulatory properties of two strains carrying either the ilvA624 or the ilvA625 mutations, located in the structural gene for threonine deaminase. Crude extracts of both these strains possess a threonine deaminase activity migrating on polyacrylamide gels, differently from the wild type enzyme. Growth studies demonstrate that these mutations do not cause a limitation of isoleucine biosynthesis, suggesting normal catalytic activity of deaminase. A regulatory consequence of the ilvA624 allele is a derepression of the isoleucine-valine biosynthetic enzymes, which is recessive to an ilvA+ allele. The ilvA625 mutation causes a derepression which is dominant in an ilvA625/ILVA+ diploid. We interpret these data assuming that threonine deaminase, previously shown to be an autogenous regulator of the ilv genes, lacks a repressor function in the ilvA624 mutant, while in the ilvA625 mutant it is a better activator than wild type threonine deaminase. The data are discussed in terms of a model requiring that threonine deaminase, or a precursor of it, is in equilibrium between two forms, one being an activator of gene expression and the other being a repressor.
Mol Gen Genet 1978 Feb 07
PMID:Dual autogenous regulatory role of threonine deaminase in Escherichia coli K-12. 34 81

Transfer RNA (tRNA), rho factor threonine deaminase and the ilvO locus are molecular participants in the regulation of isoleucine-valine (ilv) biosynthesis. Isogenic strains have been constructed with the hisT76 mutation in pairwise combination with ilvO mutations, the rho221 mutation and the ilvDAC115 deletion mutation. The role of the altered tRNA of the hisT76 mutation was found to be independent of the sites of action of the ilvO- mutation, rho factor, and threonine deaminase. The expression of the ilvOEDA operon is stimulated 2-fold when the hisT76 mutation is present in strains containing either ilvO- or rho221 mutations. The expression of the ilvOEDA operon remains nonrepressed in a hisT76 strain deleted for threonine deaminase. These results indicate that the hisT76 undermodified tRNAs are influencing the initiation of transcription of the ilvOEDA operon.
Mol Gen Genet 1978 Nov 29
PMID:A site of action for tRNA mediated regulation of the ilvOEDA operon of Escherichia coli K12. 36 86

A set of lambdadilv phage has been examined that carry overlapping segments of isoleucine-valine structural and regulatory genes derived from the ilv cluster at 83 min on the Escherichia coli K-12 chromosome. The ilv genes present in these phage, and their order, have been determined by transduction of auxotrophs, escape synthesis, and deletion mapping. The order of ilv genes in the phage, and hence the order in the host chromosome, was found to be ilvG-ilvO-ilvEDA-ilvC. Lysogens containing lambdadilv phage were constructed for dominance analysis of regulatory mutations in the ilvO and ilvA genes. The ilvO671 allele is cis-dominant to ilvO+, while the ilvA538 allele is trans-recessive to ilvA+. Thus, the ilvO gene, that is identified by cis-dominant regulatory mutations that result in increased ilvG and ilvEDA expression, is situated between and may be contiguous with ilvG and ilvEDA.
Mol Gen Genet 1979 Feb 01
PMID:Deletion mapping of the ilvGOEDAC genes of Escherichia coli K-12. 37 51

Genetic mapping experiments have established that two recently isolated valine-resistant mutants of the K-12 strain of Escherichia coli have lesions lying between ilvE and rbs. These lesions allowed expression of the ilvG gene, specifying the valine-insensitive acetohydroxy acid synthase (synthase II) and an increased expression of the ilvEDA operon. In this respect, they resembled an earlier described ilvO lesion that was reported to lie between ilvA and ilvC. All three lesions were cis-dominant in cis-trans tests. Reexamination of the earlier studied ilvO lesion revealed that it, too, lies between ilvE and rbs. Valine-sensitive derivatives with lesions presumed to be in ilvG were selected from each of the valine-resistant strains. In two of the valine-resistant strains, the ilvG mutations were on the rbs side of ilvO, indicating a gene order rbs-ilvG-ilvO-ilvE-ilvD-ilvA-ilvC. In one of the recently isolated valine-resistant stocks, however, the apparent ilvG mutation was found to be between ilvE and the aline resistance marker. This finding suggests that either ilvO and ilvG mutations are interspersed or there is another locus, ilvR, that behaves phenotypically like ilvO and which lies between ilvG and rbs.
Mol Gen Genet 1979 Feb 01
PMID:Mutations affecting the formation of acetohydroxy acid synthase II in Escherichia coli K-12. 37 52


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