Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The promoter, operator, and 5' and 3' ends of the mRNA of the Escherichia coli gene aroG (encoding the phenylalanine-sensitive 3-deoxy-arabinoheptulosonate-7-phosphate synthase) were located. Primer extension analysis and nuclease S1 mapping of in vivo transcripts were used to determine the 5' and 3' ends, respectively, of the mRNA. Both ends exhibited some heterogeneity with respect to length. The 3' end of the major molecular species was located within a region that has structural homology with known rho-independent terminators. The location of the aroG promoter was identified in both strands of the DNA by in vitro DNase I footprinting and methylation protection experiments with RNA polymerase. In these experiments, a region of up to 80 base pairs (bp) was protected by the binding of RNA polymerase. The location of the aroG operator was also identified in both strands of the DNA by in vitro DNase I footprinting with pure TyrR. TyrR protected 26 to 28 bp of DNA containing a 22-bp palindrome (TYR R box) and overlapping the -35 region of the promoter. Mutations in the aroG regulatory DNA were isolated by site-directed mutagenesis and cloned in a low-copy-number plasmid to generate aroG-lac fusions. The effects of the mutations on the regulation of aroG expression were determined by measuring the beta-galactosidase activities of the fusions in strains with tyrR, tyrR+, and multicopy tyrR+ genotypes. The results of this mutant analysis confirmed that the aroG operator contains a single TYR R box.
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PMID:Identification of the promoter, operator, and 5' and 3' ends of the mRNA of the Escherichia coli K-12 gene aroG. 197 May 63

The nucleotide sequence of the tyrP promoter region from Escherichia coli has been determined. Two TYR R boxes have been identified, and one of these was shown to overlap the -35 region of a major tyrP promoter (p1). S1 nuclease mapping of in vivo transcripts revealed that transcription from p1 is stimulated by phenylalanine and to a lesser extent by leucine. The demonstration that mutants in which TyrR-tyrosine-mediated repression of tyrP has been abolished have single base changes in the TYR R box which overlaps p1 suggests that TyrR-tyrosine-mediated repression of tyrP also involves p1. TyrR-independent stimulation of tyrP expression by Casamino Acids involves a second promoter 140 bases upstream of p1. There are no TYR R boxes in this region. The sequences of 10 TYR R boxes preceding the genes tyrP, tyrR, and aroG and the operons aroF tyrA and aroL aroM are compared and discussed.
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PMID:Molecular analysis of the promoter operator region of the Escherichia coli K-12 tyrP gene. 352 16