Putative O-antigen transport genes within the rfb region of Vibrio cholerae O1 are homologous to those for capsule transport.
The nucleotide sequence of that part of the Vibrio cholerae (Vc) O1 rfb region encompassing rfbG, rfbH and rfbI is presented. Expression of these genes has enabled the products for rfbG and rfbI to be confirmed, but the rfbH product has not been detected. Comparisons with the sequences of known proteins reveals that RfbH and RfbI are likely to be involved in the export of lipopolysaccharide (LPS). RfbH shows considerable homology to a number of integral membrane proteins, some of which have been identified as possibly having a role as an export channel for capsular polysaccharides. RfbI corresponds to an ATP-binding protein usually found linked to the membrane protein and is thought to be required for energizing this export process. Thus, we propose that RfbH and RfbI form a complex for the export of Vc O1 LPS. The function of RfbG is unknown, but it would appear to be a relatively hydrophilic protein and we can only speculate that it may be either a specific transferase or possibly the O-antigen polymerase.
Manning
P A
PA
Department of Microbiology and Immunology, University of Adelaide, Australia.
Stroeher
U H
UH
Karageorgos
L E
LE
Morona
R
R
D000595:Amino Acid Sequence; D016667:Bacterial Capsules / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001692:Biological Transport / Q000235:genetics; D004269:DNA, Bacterial; D008969:Molecular Sequence Data; D019081:O Antigens; D011135:Polysaccharides, Bacterial / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D014734:Vibrio cholerae / Q000235:genetics*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D019081:O Antigens; D011135:Polysaccharides, Bacterial; C079397:rfb protein, Bacteria