Molecular analysis of the Escherichia coli K5 kps locus: identification and characterization of an inner-membrane capsular polysaccharide transport system.
The complete nucleotide sequence has been determined of a region of the Escherichia coli K5 antigen gene cluster postulated to encode functions for the translocation of capsular polysaccharide across the inner membrane. This revealed two genes, designated kpsM and kpsT, organized in a single transcriptional unit. Analysis of the predicted amino acid sequence of the KpsM and KpsT proteins indicates that they may function as dual components in a polysaccharide export system analogous to the periplasmic binding protein-dependent transport systems of Gram-negative bacteria. We propose that the KpsT protein acts as an energizer, coupling ATP hydrolysis to the transport process mediated by the KpsM protein. Extensive sequence homology between the KpsM and KpsT proteins and the products of the bexB and bexA genes present in the capsulation (cap) locus of Haemophilus influenzae, indicates that a common mechanism for the export of polysaccharide across the inner membrane may exist in these two micro-organisms.
Smith
A N
AN
Department of Microbiology, University of Leicester, UK.
Boulnois
G J
GJ
Roberts
I S
IS
D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D005810:Multigene Family; D009693:Nucleic Acid Hybridization; D011135:Polysaccharides, Bacterial / Q000235:genetics* / Q000378:metabolism; D011487:Protein Conformation; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D011135:Polysaccharides, Bacterial; C068101:bexA protein, Haemophilus influenzae; C068104:kpsM protein, E coli; C068103:kpsT protein, E coli; C068102:bexB protein, Haemophilus influenzae