4we2

Publication Abstract from PubMed

Enterotoxigenic Escherichia coli (ETEC) strains are important causes of intestinal disease in man and lead to severe production losses in animal farming. A range of fimbrial adhesins in ETEC strains determine host and tissue tropism. ETEC strains expressing F4 fimbriae are associated with neonatal and post-weaning diarrhea in piglets. Three naturally occurring variants of F4 fimbriae (F4ab, F4ac and F4ad) exist that differ in the primary sequence of their major adhesive subunit FaeG and each feature a related but yet distinct receptor binding profile. Here the X-ray structure of FaeGad bound to lactose provides the first structural insight in the receptor specificity and mode of binding by the poly-adhesive F4 fimbriae. A small D'-D'-alpha1-alpha2 subdomain grafted on the immunoglobulin-like core of FaeG hosts the carbohydrate binding site. Two short amino acid stretches Phe150-Glu152 and Val166-Glu170 of FaeGad bind the terminal galactose in the lactosyl unit and provide affinity and specificity to the interaction. A haemagglutination based assay with E. coli expressing mutant F4ad fimbriae confirmed the elucidated co-complex structure. Interestingly the crucial D'-alpha1 loop that borders the FaeGad binding site adopts a different conformation in the two other FaeG variants and hints at a heterogeneous binding pocket amongst the FaeG serotypes.

Structural and Functional Insight in the Carbohydrate Receptor Binding of F4 Fimbriae Producing Enterotoxigenic Escherichia coli.,Moonens K, Van den Broeck I, De Kerpel M, Deboeck F, Raymaekers H, Remaut H, De Greve H J Biol Chem. 2015 Jan 28. pii: jbc.M114.618595. PMID:25631050^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.