The role of lysine-132 and arginine-136 in the receptor-binding domain of the K99 fibrillar subunit.

Abstract

The gene encoding the K99 fibrillar adhesin of Escherichia coli has been modified by oligonucleotide-directed, sitespecific, mutagenesis. The tryptophan-67, lysine-132, lysine-133 or arginine-136 were replaced by leucine, threonine, threonine and serine, respectively. The threonine-133 mutant fibrillae were indistinguishable from wild-type fibriliae. In contrast, replacement of lysine-132 or arginine-136 by threonine or serine, respectively, resulted in mutant fibrillae which had completely lost adhesive capacity, suggesting that the positive charges of these residues are essential for the interaction with the negatively charged sialic acid residue of the receptor molecules. After the replacement of tryptophan-67 with leucine neither fibrillae nor subunits were detectable, indicating that the mutant product is unstable and that tryptophan-67 has an essential structural role in the K99 subunit.

Mutational analysis of receptor binding mediated by the Dr family of Escherichia coli adhesins

“…Indeed, in the few cases where the binding domain of an adhesin has been characterized, charged amino-acids have been involved. The K99 fimbrial subunit (Jacobs et al, 1987) and the SfaS adhesin (Morschhaü ser et al, 1990) both require a lysine and an arginine residue for the recognition of the negatively charged sialic acid receptor. The mechanism by which Lys-32 and Asp-54 of the Dr haemagglutinin are involved in the recognition of the receptor is unclear.…”

Localization of a domain in the FimH adhesin of Escherichia coli type 1 fimbriae capable of receptor recognition and use of a domain-specific antibody to confer protection against experimental urinary tract infection.

“…Our studies are also consistent with earlier transposon insertion analyses of E. coli fimH that indicated mutations localized to the 5Ј region of the fimH gene were more likely to abrogate adhesive functions of the fimbriae than mutations at other sites in the gene (18). However, it is noteworthy that several other fimbrial adhesins appear to mediate binding via their carboxy terminus region (45)(46)(47)(48)(49).…”

Evolution of the Chaperone/Usher Assembly Pathway: Fimbrial Classification Goes Greek

“…Minor fimbrial subunits have been implicated in the adherence of F18 fimbriae and AF/R1 fimbriae (48,148,307). However, in the case of F4 and F5 fimbriae, minor subunits are dispensable for adherence (22,303,304), and the major fimbrial subunits (FaeG and FanC) have been implicated in determining the binding activity of their respective adhesins (21,156,250).…”