title: The Vibrio cholerae genome contains two unique circular chromosomes.
abstract: Vibrio cholerae, the etiologic agent of the diarrheal disease cholera, is a Gram-negative bacterium that belongs to the gamma subdivision of the family Proteobacteriaceae. The physical map of the genome has been reported, and the genome has been described as a single 3.2-Mb chromosome [Majumder, R., et al. (1996) J. Bacteriol. 178, 1105-1112]. By using pulsed-field gel electrophoresis of genomic DNA immobilized in agarose plugs and digested with the restriction enzymes I-CeuI, SfiI, and NotI, we have also constructed the physical map of V. cholerae. Our analysis estimates the size of the genome at 4.0 Mb, 25% larger than the physical map reported by others. Our most notable finding is, however, that the V. cholerae chromosome appears to be not the single chromosome reported but two unique and separate circular megareplicons.
authors.affiliation: Center for Vaccine Development, Division of Geographic Medicine, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA. mtrucks@umppa1.ab.umd.edu
authors.forename: M
authors.initials: M
authors.lastname: Trucksis
authors.forename: J
authors.initials: J
authors.lastname: Michalski
authors.forename: Y K
authors.initials: YK
authors.lastname: Deng
authors.forename: J B
authors.initials: JB
authors.lastname: Kaper
mesh_terms: D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial / Q000235:genetics* / Q000648:ultrastructure*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D004270:DNA, Circular / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification; D015252:Deoxyribonucleases, Type II Site-Specific; D016521:Electrophoresis, Gel, Pulsed-Field; D016680:Genome, Bacterial; D012093:Replicon; D015183:Restriction Mapping; D014734:Vibrio cholerae / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D004270:DNA, Circular; C041749:endodeoxyribonuclease SfiI; D015252:Deoxyribonucleases, Type II Site-Specific