Functional analysis of the minor subunits of S fimbrial adhesion (SfaI) in pathogenic Escherichia coli.
S fimbrial adhesins I and II (SfaI and II), produced by extraintestinal Escherichia coli pathogens that cause urinary tract infections (UTI) and newborn meningitis (NBM), respectively, mediate bacterial adherence to sialic acid-containing glycoprotein receptors present on host epithelial cells and extracellular matrix. The S fimbrial adhesin complexes consist of four proteins: SfaI-A, the major subunit protein and the minor subunit proteins SfaI-G, SfaI-S and SfaI-H. Sialic acid-specific binding is mediated by the minor subunit protein SfaI-S. In order to determine whether the minor subunit proteins SfaI-G, -S and -H play a role in the modulation of adherence and the degree of fimbriation, a trans-complementation system was developed. A non-adhesive E. coli K-12 derivative, harbouring the sfaI-A gene but lacking sfaI-G, -S and -H, was transformed with sfaI-G, -S or -H. Only SfaI-S was able to increase the degree of fimbriation and to confer adhesion properties on the recombinant E. coli K-12 strains. Amino acid residues in SfaI-S that are involved in modulation of fimbriation as well as in receptor recognition were localized by random and site-directed mutagenesis.
Khan
A S
AS
Institut für Molekulare Infektionsbiologie, Universität Würzburg, Germany. s.khan@mail.uni-wuerzburg.de
Mühldorfer
I
I
Demuth
V
V
Wallner
U
U
Korhonen
T K
TK
Hacker
J
J
D018830:Adhesins, Escherichia coli / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000472:pathogenicity / Q000502:physiology*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006801:Humans; D007231:Infant, Newborn; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000235:genetics
D018830:Adhesins, Escherichia coli; D017931:DNA Primers