title: Very-short-patch repair in Escherichia coli requires the dam adenine methylase.
abstract: Strains of Escherichia coli which lack the dam-encoded adenine methylase are mutators due to a reduction in the efficiency of postreplication mismatch repair. In this study, we show that Dam(-) strains are also defective in very-short-patch repair, the system which corrects T/G mismatches arising from the deamination of 5-methylcytosine. This defect is associated with decreased levels of Vsr, the endonuclease which initiates short-patch repair. We also show that production of the dcm-encoded cytosine methylase is unaffected in Dam(-) strains. Since the dcm and vsr genes are cotranscribed, the regulation of Vsr by Dam is probably posttranscriptional.
authors.affiliation: Biology Department, Concordia University, Montréal, Québec H3G 1M8, Canada.
authors.forename: D C
authors.initials: DC
authors.lastname: Bell
authors.forename: C G
authors.initials: CG
authors.lastname: Cupples
mesh_terms: D044503:5-Methylcytosine; D000251:Adenosine Triphosphatases; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D020137:Base Pair Mismatch; D015153:Blotting, Western; D003596:Cytosine / Q000031:analogs & derivatives / Q000378:metabolism; D019175:DNA Methylation; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D003641:Deamination; D004706:Endodeoxyribonucleases / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; D009154:Mutation; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C074770:MutL protein, E coli; D044503:5-Methylcytosine; D003596:Cytosine; C058693:Dam methyltransferase; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific); C499294:dam protein, E coli; D004706:Endodeoxyribonucleases; C059682:methyl-directed mismatch repair protein, E coli; C071421:vsr endonuclease; D000251:Adenosine Triphosphatases; D000070956:MutL Proteins; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli; D045643:DNA Repair Enzymes