Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An enzyme, 8-oxo-7,8-dihydrodeoxyguanosine triphosphatase (8-oxo-dGTPase), is present in various organisms and plays an important role in the control of spontaneous mutagenesis. The enzyme hydrolyzes 8-oxo-dGTP, an oxidized form of dGTP, to 8-oxo-dGMP, thereby preventing the occurrence of A:T to C:G transversion, caused by misincorporation. We isolated the mouse genomic sequence encoding the enzyme and elucidated its structure. The gene, named MTH1 for mutT homologue 1, is composed of at least five exons and spans approximately 9 kilobase pairs. A genomic region containing the pseudogene was also isolated. The promoter region for the gene is GC-rich, contains many AP-1 and AP-2 recognition sequences, and lacks a typical TATA box. Primer extension and S1 mapping analyses revealed the existence of multiple transcription initiation sites, among which a major site was defined as +1. The putative promoter region was placed upstream of the chloramphenicol acetyltransferase reporter gene, and control of expression of the gene was examined by introducing the construct into mouse NIH 3T3 cells. Deletion analysis indicated that a sequence from -321 to +9 carries the basic promoter activity while an adjacent region, spanning from +352 to +525 stimulates the frequency of transcription.
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PMID:Organization and expression of the mouse MTH1 gene for preventing transversion mutation. 901 34

The murine MTH1 gene codes for MTH1, an 8-oxo-2'-deoxyguanosine 5'-triphosphate pyrophosphohydrolase (8-oxo-dGTPase) which hydrolyzes 8-oxo-dGTP, a promutagenic product of reactive oxygen species' attack on the nucleotide pool. This gene is regulated by oxidative stress. Therefore, we hypothesized that MTH1 expression can be affected by carcinogenic nickel(II), known to induce such stress. Three plasmid constructs, carrying different upstream regions of the mouse MTH1 and the chloramphenicol acetyltransferase (CAT) reporter gene, were transiently transfected into NIH 3T3 cells and the CAT protein was measured in nickel(II) acetate-treated and untreated cells. Nickel concentration-dependent increase of CAT protein level was observed for low Ni(II) concentrations, up to 400 microM Ni(II), in cells transfected with pHI103 plasmid (-5969 to +530 of the MTH1 sequence) only. Cells transfected with the pHI104 (-1331 to +530) or pHI108 (-151 to +530) plasmids did not respond to nickel(II) whatsoever. This finding demonstrated that the MTH1 sequence between -5969 and -1331 contained element(s) responsive to nickel(II) treatment. DNA sequencing revealed the presence of AP-1, NF-kappaB, and ATF-1 binding sites in both the -5969 to -1331 and -1331 to +530 regions. In contrast, two (CA)n repeats (-5642 to -5582 and -2078 to -2031), a family of B2 (-5428 to -5247) and B1 (-4559 to -4420) short interspersed repeated elements, and an (AT)n repeat (-5243 to -5230) were identified only in the -5969 to -1331 sequence. The results suggest that up-regulation of murine MTH1 expression by nickel(II) is controlled by the repeat sequences, potential candidates for nickel-responsive elements.
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PMID:Presence of potential nickel-responsive element(s) in the mouse MTH1 promoter. 1131 67