title: Peptidase activity of Escherichia coli aminopeptidase A is not required for its role in Xer site-specific recombination.
abstract: Xer site-specific recombination is required for the stable inheritance of multicopy plasmids and the normal segregation of the bacterial chromosome in Escherichia coli. Two related recombinases and two accessory proteins are essential for Xer-mediated recombination at cer, a recombination site in the plasmid ColE1. The accessory proteins, ArgR and PepA, function in ensuring that the Xer recombination reaction acts exclusively intramolecularly, converting plasmid dimers into monomers and not vice versa. PepA is an amino-exopeptidase, but its molecular role in the Xer recombination mechanism is unclear. Here we show that a mutation directed at the presumptive active site of PepA creates a protein with no detectable peptidase activity in vitro or in vivo, but which still functions normally in Xer site-specific recombination at cer.
authors.affiliation: Department of Genetics, University of Glasgow, UK.
authors.forename: R
authors.initials: R
authors.lastname: McCulloch
authors.forename: M E
authors.initials: ME
authors.lastname: Burke
authors.forename: D J
authors.initials: DJ
authors.lastname: Sherratt
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000235:genetics / Q000502:physiology*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D001483:Base Sequence; D002417:Cattle; D004254:DNA Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D004151:Dipeptides / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins; D005136:Eye Proteins / Q000737:chemistry; D043384:Glutamyl Aminopeptidase; D019426:Integrases; D007931:Leucyl Aminopeptidase / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D045522:Recombinases; D011995:Recombination, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: C087018:ArgR protein, Bacteria; C490177:ArgR protein, E coli; D001426:Bacterial Proteins; D004151:Dipeptides; D029968:Escherichia coli Proteins; D005136:Eye Proteins; D011993:Recombinant Fusion Proteins; D045522:Recombinases; D012097:Repressor Proteins; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C115006:integron integrase IntI1; D000626:Aminopeptidases; D007931:Leucyl Aminopeptidase; D043384:Glutamyl Aminopeptidase