title: Identification of three noncontiguous regions on Bacillus anthracis plasmid pXO1 that are important for its maintenance.
abstract: Bacillus anthracis pXO1 minireplicon (MR) plasmid consisting of open reading frames (ORFs) GBAA_pXO1_0020 to GBAA_pXO1_0023 is not stably maintained in B. anthracis, whereas the full-size parent pXO1 plasmid (having 181,677 bp and 217 ORFs) is extremely stable under the same growth conditions. Two genetic tools developed for DNA manipulation in B. anthracis (Cre-loxP and Flp-FRT systems) were used to identify pXO1 regions important for plasmid stability. We localized a large segment of pXO1 that enables stable plasmid maintenance during vegetative growth. Further genetic analysis identified three genes that are necessary for pXO1 maintenance: amsP (GBAA_pXO1_0069), minP (GBAA_pXO1_0082), and sojP (GBAA_pXO1_0084). Analysis of conserved domains in the corresponding proteins indicated that only AmsP (activator of maintenance system of pXO1) is predicted to bind DNA, due to its strong helix-turn-helix domain. Two conserved domains were found in the MinP protein (Min protein from pXO1): an N-terminal domain having some similarity to the B. anthracis septum site-determining protein MinD and a C-terminal domain that resembles a baculovirus single-stranded-DNA-binding protein. The SojP protein (Soj from pXO1) contains putative Walker box motifs and belongs to the ParA family of ATPases. No sequences encoding other components of type I plasmid partition systems, namely, cis-acting centromere parS and its binding ParB protein, were identified within the pXO1 genome. A model describing the role of the MinP protein in pXO1 distribution between daughter cells is proposed.
authors.affiliation: National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Andrei P
authors.initials: AP
authors.lastname: Pomerantsev
authors.affiliation: National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Zanetta
authors.initials: Z
authors.lastname: Chang
authors.affiliation: National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Rappole
authors.affiliation: National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA sleppla@niaid.nih.gov.
authors.forename: Stephen H
authors.initials: SH
authors.lastname: Leppla
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001408:Bacillus anthracis / Q000235:genetics* / Q000254:growth & development; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D004261:DNA Replication; D005798:Genes, Bacterial; D042822:Genomic Instability; D008969:Molecular Sequence Data; D010957:Plasmids
chemical_list: D001426:Bacterial Proteins