DNA sequence of both chromosomes of the cholera pathogen Vibrio cholerae

Abstract

Here we determine the complete genomic sequence of the gram negative, gamma-Proteobacterium Vibrio cholerae El Tor N16961 to be 4,033,460 base pairs (bp). The genome consists of two circular chromosomes of 2,961,146 bp and 1,072,314 bp that together encode 3,885 open reading frames. The vast majority of recognizable genes for essential cell functions (such as DNA replication, transcription, translation and cell-wall biosynthesis) and pathogenicity (for example, toxins, surface antigens and adhesins) are located on the large chromosome. In contrast, the small chromosome contains a larger fraction (59%) of hypothetical genes compared with the large chromosome (42%), and also contains many more genes that appear to have origins other than the gamma-Proteobacteria. The small chromosome also carries a gene capture system (the integron island) and host 'addiction' genes that are typically found on plasmids; thus, the small chromosome may have originally been a megaplasmid that was captured by an ancestral Vibrio species. The V. cholerae genomic sequence provides a starting point for understanding how a free-living, environmental organism emerged to become a significant human bacterial pathogen.

The bacterial nucleoid: A highly organized and dynamic structure

“…Chromosome I contains most of the essential genes, while chromosome II only carries a few essential functions and is probably derived from a megaplasmid [Heidelberg et al, 2000]. The replication origins of these two chromosomes localize to distinct positions during all stages of the cell cycle .…”

Independent Segregation of the Two Arms of theEscherichia coli oriRegion Requires neither RNA Synthesis nor MreB Dynamics

“…Later, it was found that many bacterial chromosomes also utilize parABS systems for their segregation, for example, Bacillus subtilis (23,37), Caulobacter crescentus (41), and both chromosomes of Vibrio cholerae (22). The typical chromosomal par locus consists of two genes, parA and parB (soj and spo0J in B. subtilis), and a cis-acting parS DNA element.…”

“…The latter requirement may be due to the fact that chromosome II has many properties of a large plasmid and its Par proteins are more closely related to plasmid-encoded ones than to those encoded on chromosomes (22). In C. crescentus, the par system may be essential only indirectly, as it is used for proper localization of the cell division machinery through at least two other proteins, PopZ (6,13) and MipZ (53).…”

Proteomics of marine bacteria

“…The causative agent of cholera occurs naturally attached to the phyto-and zooplankton of fresh, brackish and salt water. The complete DNA sequence of the two chromosomes of V. cholerae was published in 2000 [93]. Proteome reference maps have been established for two strains [88,89], providing the basis for further comparative analyses.…”