Adhesins fimbrial

The initial adherence of pathogens to host cell surfaces is considered an essential step in colonization and infection (Savage, 1977, 1984). Therefore, identifying the bacterial molecules that mediate adherence has been a major area of research, especially since these molecules may serve as targets for anfi-adherence strategies. As discussed previously (Section VI), the detailed interactions between a pathogen and a host cell are often mediated by proteinaceous surface structures on the bacterial surface. These bacterial proteins are referred to as adhesins (Finlay and Falkow, 1989), and are most often foimd on the tips of bacterial fimbriae or pili (fimbrial adhesins), but may also be anchored in the bacterial membrane so that it can be presented on the bacterial outer membrane (afimbrial adhesins) (Sharon and Ofek, 1986). Models of fimbrial and afimbrial adhesins of some human pathogens are discussed here. 

Recently, a non-fimbrial adhesin, SiiE, has been identified in S. enterica serovar T)q)himurim. Although little is known about SiiE, it has been found to mediate contact-dependent adhesion to HeLa cell surfaces (Gerlach et al., 2007). SiiE is a type 1 secretion system (TISS) secreted protein encoded m the Salmonella pathogenicity island 4 and might functionally resemble the type 1 fimbrial adhesins. More work is needed to elucidate the true role of SiiE in adherence in vivo. 

Baumler, A. J., Tsolis, R. M., and Heffron, F. (1997). Fimbrial adhesins of Salmonella typhimurium. Role in bacterial interactions with epithelial cells. Adv. Exp. Med. Biol. 412,149-158. 

Bilge, S. S., Clausen, C. R., Lau, W., and Moseley, S. L. (1989). Molecular characterization of a fimbrial adhesin, F1845, mediating diffuse adherence of diarrhea associated Escherichia coli to HEp-2 cells. /. Bacteriol. 171, 4281-4289. 

Gerlach, R. G., Jackel, D., Stecher, B., Wagner, C., Lupas, A., Hardt, W.-D., and Hensel, M. (2007). Salmonella pathogenicity island 4 encodes a giant non-fimbrial adhesin and the cognate type 1 secretion system. Cell. Microbiol. 9,1834-1850. 

Sokurenko, E. V., Courtney, H. S., Ohman, D. E., Klemm, P., and Hasty, D. L. (1994). FimH family of type 1 fimbrial adhesins Functional heterogeneity due to minor sequence variations among finiH genes. J. Bacterial. 176, 748-755. 

Gouin et al. described a heptavalent a-Man-based glycocluster (Fig. 16.9a) as a strong inhibitor to block the hemagglutination of type 1 fimbrial adhesins of E. coli... 

Fimbrial adhesins may be visualized by electron microscopy. However, the processing for analysis by electron microscopy might cause alterations of the specimens, e.g. by dehydration. This might result in the collapse of certain fimbriae. Therefore, despite no fimbriae are visible by electron microscopy the afimbrial adhesins of the Dr family, e.g. AfaE of diarrheagenic and uropathogenic E. coli in fact assemble... 

Buts L, Bouckaert J, De Genst E et al. (2003) The fimbrial adhesin F17-G of enterotoxigenic E. coli has an immunoglobulin like lectin domain that binds A-acetylgl ucosam i ne. Mol... 

The most common group of fimbrial adhesins of Escherichia coli occurs at the edge of their fimbriae and have a two-domain organization. The most external N-terminal domain is a lectin, whereas the C-terminal pilin connects to the rest of the fimbrius. In Fig. 5, the lectin domains from E. coli adhesins that have been crystallised in complex with a specific glycan sequence are displayed, with the exception of CfaE that was only crystallized in its glycan-free form. PapGII (Pap for pyelonephritis associated pili) is the fimbrial adhesin at the tip of P fimbriae from... 

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