Use of a wild-type gene fusion to determine the influence of environmental conditions on expression of the S fimbrial adhesin in an Escherichia coli pathogen.
S fimbrial adhesins (Sfa) enable pathogenic Escherichia coli strains to bind to sialic acid-containing eucaryotic receptor molecules. In order to determine the influence of culture conditions on the expression of the sfa determinant in a wild-type strain, we fused the gene lacZ, coding for the enzyme beta-galactosidase, to the sfaA gene, responsible for the major protein subunit of S fimbriae. By using a plasmid which carries an R6K origin, the sfaA-lac hybrid construct was site-specifically integrated into the chromosome of the uropathogenic E. coli strain 536WT. The expression of lacZ, which was under the control of the sfa wild-type promoters, was now equivalent to the sfa expression of strain 536WT. With the help of this particular wild-type construct, it was demonstrated that the sfa determinant is better expressed on solid media than in liquid broth. The growth rate had a strong influence on Sfa expression under aerobic but not under anaerobic conditions. Production of Sfa was further regulated by catabolite repression, osmolarity, and temperature.
Schmoll
T
T
Institut für Genetik und Mikrobiologie, University of Würzburg, Federal Republic of Germany.
Ott
M
M
Oudega
B
B
Hacker
J
J
D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics*; D015139:Blotting, Southern; D003001:Cloning, Molecular / Q000379:methods*; D015342:DNA Probes; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity; D007700:Kinetics; D009876:Operon; D010957:Plasmids; D014176:Protein Biosynthesis; D015183:Restriction Mapping; D013696:Temperature; D014774:Virulence / Q000235:genetics; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins; D015342:DNA Probes; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D001616:beta-Galactosidase