Amylases and their importance during glycan degradation

Contributed by Narine Arabyan

Amylases catalyze the cleavage of α-D-1,4 and α-D-1,6-glycosidic bonds in starch and related carbohydrates. Amylases are widely distributed in nature and are important in carbohydrate metabolism. Amylases in Salmonella are poorly characterized glycosyl hydrolases. The importance of amylases during Salmonella infection is understudied, especially as new virulence factors. The genome of Salmonella Typhimurium LT2 contains four amylases that are classified under GH13 family: malS (periplasmic α-amylase), amyA (cytoplasmic α-amylase), glgX (glycogen debranching enzyme) and glgB (1,4-α-glucan branching enzyme). Although glgX and glgB are not annotated as amylases, both have a conserved α-amylase domain and function as amylases. Investigating the genomic diversity of microbial amylases will aid in understanding their importance during pathogenesis. Inhibitors of amylases can be new drug targets. Amylases play an important role by altering the host glycan profiles during infection to gain access of the host epithelial cells by binding to terminal mannose molecules to initiate glycan degradation (1). Weimer’s group also demonstrated that each of the four mutant amylase strains (ΔmalS, ΔamyA, ΔglgX, and ΔglgB) had different invasion phenotypes during the in vitro infection of differentiated colonic epithelial cells (Caco-2) (1); however only ΔmalS significantly (p<0.05) reduced adhesion and invasion during infection that were comparable to a non-pathogenic Salmonella strain (1).

  1. Arabyan N, Park D, Foutouhi S, Weis AM, Huang BC, Williams CC, Desai P, Shah J, Jeannotte R, Kong N, Lebrilla CB, Weimer BC. 2016. Salmonella Degrades the Host Glycocalyx Leading to Altered Infection and Glycan Remodeling. Sci Rep 6:29525.

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