title: Genetic and physical mapping of the mcrA (rglA) and mcrB (rglB) loci of Escherichia coli K-12.
abstract: We have genetically analyzed, cloned and physically mapped the modified cytosine-specific restriction determinants mcrA (rglA) and mcrB (rglB) of Escherichia coli K-12. The independently discovered Rgl and Mcr restriction systems are shown to be identical by three criteria: 1) mutants with the RglA- or RglB- phenotypes display the corresponding McrA- or McrB- phenotypes, and vice versa; 2) the gene(s) for RglA and McrA reside together at one locus, while gene(s) for RglB and McrB are coincident at a different locus; and 3) RglA+ and RglB+ recombinant clones complement for the corresponding Mcr-deficient lesions. The mcrA (rglA) gene(s) is on the excisable element e14, just clockwise of purB at 25 min. The mcrB (rglB) gene(s), at 99 min, is in a cluster of restriction functions that includes hsd and mrr, determinants of host-specific restriction (EcoK) and methyladenine-specific restriction respectively. Gene order is mcrB-hsdS-hsdM-hsdR-mrr-serB. Possible models for the acqusition of these restriction determinants by enteric bacteria are discussed.
authors.affiliation: New England BioLabs, Beverly, Massachusetts 01915-9990.
authors.forename: E A
authors.initials: EA
authors.lastname: Raleigh
authors.forename: R
authors.initials: R
authors.lastname: Trimarchi
authors.forename: H
authors.initials: H
authors.lastname: Revel
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002874:Chromosome Mapping; D004262:DNA Restriction Enzymes / Q000235:genetics* / Q000378:metabolism; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D005796:Genes; D005798:Genes, Bacterial; D008957:Models, Genetic; D014161:Transduction, Genetic
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D004262:DNA Restriction Enzymes; C060629:endodeoxyribonuclease McrA; C059678:mcrB protein, E coli