Question

Lectins are carbohydrate-binding proteins that have been implicated in a wide range of disease conditions in humans. Discuss the role of bacterial lectins in the mechanism of human infection. Use the following questions to guide your answer:

a. How does the typical molecular structure of lectins look?

b. What chemistry is involved when lectins bind specifically to carbohydrates?

c. How does lectin-ligand binding lead to entry of the bacterium into a host cell?

d. What is an example of a bacterial disease that is facilitated by this mechanism?

Answer 1

a. Lectin's structures are similar to the structure of protein.

b. Lectins are carbohydrate-binding proteins and the carbohydrate-binding specificity of a lectin is determined by the amino acid residues, that bind the carbohydrates. They are highly specific for sugar groups of other molecules or they have high specificity to bind glycan weakly.

c. Bacterial surface lectins, commonly in the form of fimbriae, serves primary function in the initiation of infection by mediating bacterial adherence to epithelial cells of host.

Lectins are highly specific for sugars and have a role in recognition on cellular and molecular level. They mediate attachment and binding of bacteria to their intended targets. To avoid clearance from host body, bacteria express surface lectins, called adhesins. This bind to tissue specific glycans on host cell-surface glycoprotein and glycolipids.

d. Diarrhoea and urinary infections.

These disease are accompanied by bacteria with the help of lectins.