Beyond FimH: Diversity and Relevance of Carbohydrate-Binding Fimbrial Proteins in Escherichia coli

Escherichia coli (E. coli) is responsible for multiple diseases in humans and animals. Many of them are treated with antibiotics; however, the need for new therapies has led to research in alternative treatments. One such approach involves preventing the adherence of E. coli to host cells by inhibiting their adhesins. Adherence is a crucial step of pathogenesis, and bacterial lectins that recognize host glycans play major roles in host cell adhesion. In fact, lectins are the most common bacterial adhesins. The various pathogenic and nonpathogenic E. coli strains express a multitude of lectins, many of which are found on E. coli fimbriae. Current research on lectin inhibition using glycomimetics has produced many mannose-based inhibitors of the uropathogenic E. coli fimbrial lectin FimH. However, only a limited number of synthetic inhibitors are reported for other lectins. In this review, many other cell surface adhesins of E. coli are discussed, focusing on fimbrial lectins. The types of E. coli strains they are found in, their carbohydrate targets, and their binding sites are also discussed. This review aims to highlight the many lectins that can become therapeutic targets to treat E. coli infections in addition to FimH.