Novel Vibrio cholerae O139 genes involved in lipopolysaccharide biosynthesis

Abstract

The sequence of part of the rfb region of Vibrio cholerae serogroup O139 and the physical map of a 35-kb region of the O139 chromosome have been determined. The O139 rfb region presented contains a number of open reading frames which show similarities to other rfb and capsular biosynthesis genes found in members of the Enterobacteriaceae family and in V. cholerae O1. The cloned and sequenced region can complement the defects in O139 antigen biosynthesis in transposon insertions within the O139 rfb cluster. Linkage is demonstrated among IS1358 of V. cholerae O139, the rfb region, and the recently reported otnA and otnB genes (E. M. Bik, A. E. Bunschoten, R. D. Gouw, and F. R. Mooi, EMBO J. 14:209-216, 1995). In addition, the whole of this region has been linked to the rfaD gene. Furthermore, determination of the sequence flanking IS1358 has revealed homology to other rfb-like genes. The exact site of insertion with respect to rfaD is defined for the novel DNAs of both the Bengal and the Argentinian O139 isolates.Until recently only Vibrio cholerae strains of the O1 serogroup have been known to cause widespread epidemics of cholera, but with the emergence of the O139 serogroup, this is no longer true (22,36,38,43). Extensive studies have shown that V. cholerae O139 has most probably been derived from an El Tor O1 strain by the acquisition of new polysaccharide genes and the subsequent or simultaneous deletion of the V. cholerae O1 rfb genes (26, 33). It is the rfb gene cluster which determines the serogroup in V. cholerae. Southern hybridization and PCR analysis of the O139 chromosome has revealed that there exist several regions of homology linked to the O1 rfb region (33, 45). The rfaD gene thought to be responsible in part for core biosynthesis (47) remains as do regions 3Ј of rfaD. The other homologous region comprises the three open reading frames (ORFs) known as rfbQ, -R, and -S (IS1358dl) in V. cholerae O1, which correspond to a defective form of IS1358 which shows homology to the Hinc repeat (H-rpt) of the rearrangement hot spot (RHS) element found in Escherichia coli (6,18,45).

Use of chromosomal integron arrays as a phylogenetic typing system for Vibrio cholerae pandemic strains

“…A deletion in O1 El Tor C31 compared to other O1 V. cholerae in a region now identified as the MGC array has been reported in earlier studies (Barker & Clark, 1994;van Dongen & DeGraaf, 1986). Earlier studies have concluded that, unlike O139 Bengal strains, Arg3 is not derived from a V. cholerae O1 parent and has evolved independently (Stroeher et al, 1995(Stroeher et al, , 1997. This is supported by the recA phylogenetic analysis (Stine et al, 2000;Fig.…”

Functional analysis of genes responsible for the synthesis of the B-band O antigen of Pseudomonas aeruginosa serotype O6 lipopolysaccharide The GenBank accession number for the sequence reported in this paper is AF035937.

“…WbfT has been putatively assigned the UDP-galactose-4-epimerase function (Comstock et al, 1996 ;Stroeher & Manning, 1997). WbpV also has 34n4 % identity to P. aeruginosa WbpK O& , which has been proposed to be required for the biosynthesis of UDP-Fuc2NAc (Burrows et al, 1996).…”

Molecular evolution of Vibrio pathogenicity island-2 (VPI-2): mosaic structure among Vibrio cholerae and Vibrio mimicus natural isolates

“…The V. cholerae O139 serogroup first emerged in 1992 as a cause of epidemic cholera (Albert et al, 1993;Cholera Working Group, 1993). It is now believed that O139 serogroup isolates arose from an O1 strain that acquired the O139 antigen (Berche et al, 1994;Bik et al, 1995;Stroeher et al, 1997;Waldor & Mekalanos, 1994). All V. cholerae O1 and O139 serogroup isolates encode two main virulence factors: toxin co-regulated pilus (TCP) and cholera toxin (CT).…”