Role of different genes in the CS6 operon for surface expression of Enterotoxigenic Escherichia coli colonization factor CS6.
Coli surface antigen 6, CS6, is one of the most prevalent colonization factors (CFs) associated with Enterotoxigenic Escherichia coli (ETEC) bacteria, the most common cause of diarrhea among infants and children in developing countries. The CS6 operon encodes two structural subunit proteins, CssA and CssB, a chaperon, CssC, and an usher, CssD. Since little is known about the relationship of the genes and their role in expression and surface assembly of CS6, the operon was cloned into a laboratory E. coli strain, and mutants were constructed by creating deletions in each of the genes. Examination of protein expression by different methods, using monoclonal antibodies with specificities for the individual CS6 structural proteins, suggested that the usher (CssD) was not involved in assembly or surface expression of CS6 whereas deletion of the chaperon (CssC) significantly reduced levels of CssA, but not of CssB. Binding studies with CaCo-2 cells demonstrated that there is a combined effect of CssC and CssD on receptor binding, presumably associated with their activities in assembly and transport of the structural subunits. These findings may have important implications for the construction of strains expressing high levels of CS6 on the surface for eventual use in an ETEC vaccine.
Tobias
Joshua
J
WHO Collaborating Centre for Research on Enterotoxigenic Escherichia coli (ETEC), and Department of Microbiology and Immunology, Institute of Biomedicine, Göteborg University, 40530 Göteborg, Sweden. Joshua.Tobias@microbio.gu.se
Lebens
Michael
M
Källgård
Susanne
S
Nicklasson
Matilda
M
Svennerholm
Ann-Mari
AM
D000907:Antibodies, Bacterial / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000942:Antigens, Bacterial / Q000235:genetics* / Q000378:metabolism; D001422:Bacterial Adhesion; D002460:Cell Line; D003001:Cloning, Molecular; D054307:Enterotoxigenic Escherichia coli / Q000235:genetics* / Q000378:metabolism; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D036781:Fimbriae Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006801:Humans; D009154:Mutation; D009876:Operon
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; C098406:CS6 antigen, E coli; D029968:Escherichia coli Proteins; C022924:colonization factor antigens; D036781:Fimbriae Proteins