title: An attenuated strain of Bacillus anthracis (CDC 684) has a large chromosomal inversion and altered growth kinetics.
abstract: BACKGROUND
  An isolate originally labeled Bacillus megaterium CDC 684 was found to contain both pXO1 and pXO2, was non-hemolytic, sensitive to gamma-phage, and produced both the protective antigen and the poly-D-glutamic acid capsule. These phenotypes prompted Ezzell et al., (J. Clin. Microbiol. 28:223) to reclassify this isolate to Bacillus anthracis in 1990.
  
  
  RESULTS
  We demonstrate that despite these B. anthracis features, the isolate is severely attenuated in a guinea pig model. This prompted whole genome sequencing and closure. The comparative analysis of CDC 684 to other sequenced B. anthracis isolates and further analysis reveals: a) CDC 684 is a close relative of a virulent strain, Vollum A0488; b) CDC 684 defines a new B. anthracis lineage (at least 51 SNPs) that includes 15 other isolates; c) the genome of CDC 684 contains a large chromosomal inversion that spans 3.3 Mbp; d) this inversion has caused a displacement of the usual spatial orientation of the origin of replication (ori) to the termination of replication (ter) from 180° in wild-type B. anthracis to 120° in CDC 684 and e) this isolate also has altered growth kinetics in liquid media.
  
  
  CONCLUSIONS
  We propose two alternative hypotheses explaining the attenuated phenotype of this isolate. Hypothesis 1 suggests that the skewed ori/ter relationship in CDC 684 has altered its DNA replication and/or transcriptome processes resulting in altered growth kinetics and virulence capacity. Hypothesis 2 suggests that one or more of the single nucleotide polymorphisms in CDC 684 has altered the expression of a regulatory element or other genes necessary for virulence.
authors.affiliation: Center for Microbial Genetics and Genomics, Northern Arizona University, Flagstaff, AZ 86011, USA. Richard.Okinaka@nau.edu
authors.forename: Richard T
authors.initials: RT
authors.lastname: Okinaka
authors.forename: Erin P
authors.initials: EP
authors.lastname: Price
authors.forename: Spenser R
authors.initials: SR
authors.lastname: Wolken
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Gruendike
authors.forename: Wai Kwan
authors.initials: WK
authors.lastname: Chung
authors.forename: Talima
authors.initials: T
authors.lastname: Pearson
authors.forename: Gary
authors.initials: G
authors.lastname: Xie
authors.forename: Chris
authors.initials: C
authors.lastname: Munk
authors.forename: Karen K
authors.initials: KK
authors.lastname: Hill
authors.forename: Jean
authors.initials: J
authors.lastname: Challacombe
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Ivins
authors.forename: James M
authors.initials: JM
authors.lastname: Schupp
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Beckstrom-Sternberg
authors.forename: Arthur
authors.initials: A
authors.lastname: Friedlander
authors.forename: Paul
authors.initials: P
authors.lastname: Keim
mesh_terms: D001408:Bacillus anthracis / Q000145:classification / Q000235:genetics* / Q000254:growth & development*; D001483:Base Sequence; D007446:Chromosome Inversion; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide