Site-specific recombinase genes in three Shigella subgroups and nucleotide sequences of a pinB gene and an invertible B segment from Shigella boydii.
Inversional switching systems in procaryotes are composed of an invertible DNA segment and a site-specific recombinase gene adjacent to or contained in the segment. Four related but functionally distinct systems have previously been characterized in detail: the Salmonella typhimurium H segment-hin gene (H-hin), phage Mu G-gin, phage P1 C-cin, and Escherichia coli e14 P-pin. In this article we report the isolation and characterization of three new recombinase genes: pinB, pinD, and defective pinF from Shigella boydii, Shigella dysenteriae, and Shigella flexneri, respectively. The genes pinB and pinD were detected by the complementation of a hin mutation of Salmonella and were able to mediate inversion of the H, P, and C segments. pinB mediated H inversion as efficiently as the hin gene did and mediated C inversion with a frequency three orders of magnitude lower than that of the cin gene. pinD mediated inversion of H and P segments with frequencies ten times as high as those for the genes intrinsic to each segment and mediated C inversion with a frequency ten times lower than that for cin. Therefore, the pinB and pinD genes were inferred to be different from each other. The invertible B segment-pinB gene cloned from S. boydii is highly homologous to the G-gin in size, organization, and nucleotide sequence of open reading frames, but the 5' constant region outside the segment is quite different in size and predicted amino acid sequence. The B segment underwent inversion in the presence of hin, pin, or cin. The defective pinF gene is suggested to hae the same origin as P-pin on e14 by the restriction map of the fragment cloned from a Pin+ transductant that was obtained in transduction from S. flexneri to E. coli delta pin.
Tominaga
A
A
Department of Biology, Faculty of Science, Okayama University, Japan.
Ikemizu
S
S
Enomoto
M
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D015139:Blotting, Southern; D007446:Chromosome Inversion; D004254:DNA Nucleotidyltransferases / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D019426:Integrases; D008969:Molecular Sequence Data; D045522:Recombinases; D012486:Salmonella typhimurium / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D012761:Shigella boydii / Q000201:enzymology / Q000235:genetics*; D012762:Shigella dysenteriae / Q000235:genetics; D014161:Transduction, Genetic
D045522:Recombinases; D004254:DNA Nucleotidyltransferases; D019426:Integrases; C115006:integron integrase IntI1