SusE and SusF are two outer membrane proteins composed of tandem starch specific carbohydrate binding modules (CBMs) with no enzymatic activity. They are are likely to play an important role in starch metabolism in Bacteroides. It has been speculated that they could compete for starch in the human intestinal tract by sequestering starch at the bacterial surface and away from competitors [1]. SusE has higher affinity for starch compared to SusF.

1: Multidomain Carbohydrate-binding Proteins Involved in Bacteroides thetaiotaomicron Starch Metabolism. Cameron EA, Maynard MA, Smith CJ, Smith TJ, Koropatkin NM, Martens EC; J Biol Chem. 2012;287:34614-34625. PMID:22910908