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 genes for dichloromethane utilization by Methylobacterium sp. strain DM4 are encoded on a 2.8-kb sequenced DNA fragment, the dcm region. This fragment contains dcmA, the structural gene of dichloromethane dehalogenase and, upstream of dcmA, a 1.5-kb region responsible for inducibility of dichloromethane dehalogenase by dichloromethane. A fragment of the dcm region covering dcmA and 230 bp of its upstream region was integrated into the chromosome of a Methylobacterium sp. strain DM4 mutant deleted for the dcm region. This yielded a strain expressin dichloromethane dehalogenase constitutively at the induced level. Plasmids carrying various segments of the 1.5-kb regulatory region were tested for their ability to restore regulation. The data obtained led to the identification of dcmR, the structural gene of a putative dcm-specific repressor. Transcription of dcmR was divergent from dcmA. dcmR encoded a 30-kDa protein with a helix-turn-helix motif near the amino terminus. The transcription start sites of dcmA and dcmR were identified by nuclease S1 mapping. The promoter regions of these genes contained nearly identical 12-bp sequences covering positions -14 to -25 relative to the mRNA start sites. Experiments with dcmR'-'lacZ fusions demonstrated that dcmR expression was markedly autoregulated at the level of transcription and less so at the protein level. These findings are compatible with both dcmA and dcmR expression being negatively controlled at the transcriptional level by the DcmR protein.
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PMID:Identification of dcmR, the regulatory gene governing expression of dichloromethane dehalogenase in Methylobacterium sp. strain DM4. 193 78

The nucleotide sequence of a cloned 2.8-kilobase-pair BamHI-PstI fragment containing dcmA, the dichloromethane dehalogenase structural gene from Methylobacterium sp. strain DM4, was determined. An open reading frame with a coding capacity of 287 amino acids (molecular weight, 37,430) was identified as dcmA by its agreement with the N-terminal amino acid sequence, the total amino acid composition, and the subunit size of the purified enzyme. Alignment of the deduced dichloromethane dehalogenase amino acid sequence with amino acid sequences of the functionally related eucaryotic glutathione S-transferases revealed three regions containing highly conserved amino acid residues and indicated that dcmA is a member of the glutathione S-transferase supergene family. The 5' terminus of in vivo dcmA transcripts was determined by nuclease S1 mapping to be 82 base pairs upstream of the GTG initiation codon of dcmA. Despite a putative promoter sequence with high resemblance to the Escherichia coli -10 and -35 consensus sequences, located at an appropriate distance from the transcription start point, dcmA was only marginally expressed in E. coli. The strong induction of dichloromethane dehalogenase in Methylobacterium sp. by dichloromethane was abolished by deleting the 1.3-kilobase-pair upstream region of dcmA. Plasmid constructs devoid of this region directed expression of dichloromethane dehalogenase at a constitutively induced level.
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PMID:Sequence analysis and expression of the bacterial dichloromethane dehalogenase structural gene, a member of the glutathione S-transferase supergene family. 210 2