Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ability of a series of haloalkanes, haloethanols and haloacetaldehydes to induce mutations in Salmonella typhrimurium and preferentially to inhibit the growth of DNA polymerase-deficient E. coli (pol A(+)/pol A(-)) was investigated. For the haloalkanes investigated, the order of reactivities towards the E. coli pol A(+)/pol A(-), was: 1,1,2,2-tetrabromoethane > 1,1-dibromoethane > 1,1,2,2-tetrachlorethane > 1,2-dibromoethane = 1,5 dibromopentane > 1,2-dibromo-2-methylpropane > 1-bromo-2-chloroethane > 1,2-dichloroethane. In the standard Salmonella mutagenicity assay the order of these substances was 1,2-dibromoethane = 1,5-dibromopentane > 1,2-dibromo-2-methylpropane >/= 1-bromo-2-chloroethane > 1,1,2,2-tetrachloroethane = 1,1-dibromoethane > 1,2-dichloroethane. 1,1,2,2-Tetrabromoethane was negative in the standard assay but strongly mutagenic when tested in suspension. It would appear that the discrepancy between the two procedures is due to the fact that bactericidal mutagens cannot be scored reliably in the standard Salmonella assay. The order of reactivity of 2-haloethanols in E. coli pol. A(+)/pol A(-), was 2-iodo > 2-bromo-> 2-chloroethanol. In the Salmonella assay the order was 2-bromo-> 2 iodo- >2-chloro-ethanol. 2-Fluoroethanol and ethanol were devoid of activity in both assays. For the 2-haloacetaldehydes the reactivities in the E. coli system were 2-bromoethylacetate > 2-bromoacetaldehyde = acetaldehyde > 2-chloroacetaldehyde while in the Salmonella system the order was 2-bromoethylacetate > 2-chloroacetaldehyde. Acetaldehyde had minimal activity, while 2-bromoacetaldehyde was without activity but strongly bactericidal.
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PMID:Mutagenicity of halogenated alkanes and their derivatives. 34 60

2-Chloroacetaldehyde (CAA), a metabolite of the carcinogenic industrial chemical vinyl chloride, reacts with single-stranded DNA to form the cyclic etheno lesions predominantly at adenine and cytosine. In both ethenoadenine and ethenocytosine, normal Watson-Crick hydrogen-bonding atoms are compromised. We have recently shown that CAA adduction leads to efficient mutagenesis in Escherichia coli predominantly at cytosines, and less efficiently at adenines. About 80% of the mutations at cytosines were C-to-T transitions, and the remainder were C-to-A transversions, a result similar to that of many noninstructional DNA lesions opposite which adenine residues are preferentially incorporated. It is widely believed that noninstructional lesions stop replication and depend on SOS functions for efficient mutagenesis. We have examined the effects of in vitro CAA adduction of the lacZ alpha gene of phage M13AB28 on in vivo mutagenesis in SOS-(UV)-induced E. coli. CAA adduction was specifically directed to a part of the lacZ sequence within M13 replicative form DNA by a simple experimental strategy, and the DNA was transfected into appropriate unirradiated or UV-irradiated cells. Mutant progeny were defined by DNA sequencing. In parallel in vitro experiments, the effects of CAA adduction on DNA replication by E. coli DNA polymerase I large (Klenow) fragment were examined. Our data do not suggest a strong SOS dependence for mutagenesis at cytosine lesions. While adenine lesions remain much less mutagenic than cytosine lesions, mutation frequency at adenines is increased by SOS. SOS induction does not significantly alter the specificity of base changes at cytosines or adenines.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mechanisms of mutagenesis by the vinyl chloride metabolite chloroacetaldehyde. Effect of gene-targeted in vitro adduction of M13 DNA on DNA template activity in vivo and in vitro. 240 5

Chloroacetaldehyde, a rearranged metabolic product of the human carcinogen vinyl chloride, reacts with the DNA-like polymers poly(dA-dT) and poly(dC-dG) to form etheno-adducts of the adenine and cytosine bases. These treated polymers, when used as templates for E. coli DNA polymerase I in an in vitro assay, show a decreased ability to direct DNA synthesis. At the same time, increased relative levels of non-complementary nucleotides are incorporated. With the poly(dA-dT) templates 1 dGMP residue is incorporated for every approx 60 ethenoadenine residues present whilst no increased misincorporation of dCMP was detected. With the poly(dC-dG) templates 1 misincorporation of dAMP or dTMP occurred in the presence of approx 30 and 80 ethenocytosine residues respectively. A nearest neighbour analysis shows that with the modified poly(dC-dG) templates the majority of the errors were incorporated opposite cytosine (or modified cytosine) bases.
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PMID:The induction of errors during in vitro DNA synthesis following chloroacetaldehyde-treatment of poly(dA-dT) and poly(dC-dG) templates. 702 22

Chloroacetaldehyde (CAA) reacts with DNA bases, forming hydroxyethano derivatives of different stability, which are subsequently converted into etheno (epsilon) adducts: epsilon A, epsilon C, epsilon G. DNA polymerase fingerprint analysis was used to study the distribution of CAA-induced modifications in the p53 sequence. A plasmid bearing cDNA containing the human p53 gene was reacted in vitro with CAA, then dehydrated for conversion of hydroxyethano into etheno adducts, and primer extension by T7 DNA polymerase in the presence of four dNTPs was performed. The DNA repair enzymes methylpurine-DNA glycosylase and Escherichia coli exonuclease III were used to convert epsilon A residues in the template into DNA strand breaks, which enabled precise localization of the epsilon A residues within the p53 gene. Hydroxyethano derivatives of adenine and cytosine in a template blocked T7 DNA polymerase and caused premature chain termination opposite adenine or one base before cytosine. After dehydration, both epsilon A and epsilon C were much more easily by-passed by T7 DNA polymerase. Formation of epsilon G was identified as 'stop bands' one base before guanine residues. Modification of cytosine and guanine was additionally recognized by weakening or disappearance of non-specific stops on an undamaged template, probably due to steric hindrance by the tertiary DNA structure for polymerase. Etheno adduction of cytosine and guanine relaxed the compact DNA structure and enabled DNA polymerase to by-pass. In exons 5-8 of p53, 143 out of 500 sites appeared to be damaged by CAA, with four particularly densely modified regions between codons 135-147, 218-222, 234-255 and 284-292. The pattern of modification followed the pattern of p53 mutations found in vinyl chloride-associated liver angiosarcomas in humans and rats, but only in regions that showed 100% homology with the human sequence. The factors that influence DNA damage and induction of mutations in the p53 gene by CAA and vinyl chloride are discussed.
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PMID:Localization of chloroacetaldehyde-induced DNA damage in human p53 gene by DNA polymerase fingerprint analysis. 1062 28