The Escherichia coli G-fimbrial lectin protein participates both in fimbrial biogenesis and in recognition of the receptor N-acetyl-D-glucosamine.
The gafD gene encoding the N-acetyl-D-glucosamine-specific fimbrial lectin (adhesin) protein GafD of uropathogenic Escherichia coli was cloned and subjected to genetic analysis. The corresponding gene product was isolated as a MalE fusion protein. The lectin gene was identified with the aid of deletion mutagenesis; mutations in gafD impaired either receptor binding or both receptor binding and fimbria production, depending on the mutation created. All mutants converted to wild-type expressors when complemented in trans with the cloned intact gafD gene. The predicted 354-amino-acid sequence of GafD, deduced from the nucleotide sequence, is closely related to those of the fimbria-associated F17-G and F17b-G proteins coded for by enterotoxigenic and invasive E. coli strains. Isolated GafD was shown to recognize N-acetyl-D-glucosamine by virtue of specific binding to an immobilized receptor, thus proving directly that GafD is a sugar-binding protein. Our results indicate that GafD as such is sufficient for receptor recognition and that the protein also participates in fimbrial biogenesis.
Saarela
S
S
Department of Pharmacy (Microbiology Division), University of Helsinki, Finland.
Taira
S
S
Nurmiaho-Lassila
E L
EL
Makkonen
A
A
Rhen
M
M
D000117:Acetylglucosamine / Q000378:metabolism*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion / Q000235:genetics / Q000502:physiology; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D005798:Genes, Bacterial / Q000235:genetics; D006386:Hemagglutination Tests; D037102:Lectins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D009024:Morphogenesis; D011956:Receptors, Cell Surface / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D037102:Lectins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D000117:Acetylglucosamine