Molecular details of a starch utilization pathway in the human gut symbiont Eubacterium rectale

摘要: Eubacterium rectale is a prominent human gut symbiont yet little known about the molecular strategies this bacterium has developed to acquire nutrients within competitive ecosystem. Starch one of most abundant glycans in diet, and E. rectale increases vivo when host consumes diet rich resistant starch, although it not primary degrader glycan. Here we present results quantitative proteomics study which identify two glycoside hydrolase 13 family enzymes, three ABC transporter solute-binding proteins that are during growth on starch and, hypothesize, work together at cell surface degrade capture released maltooligosaccharides. EUR_21100 multidomain wall anchored amylase preferentially targets polysaccharides, liberating maltotetraose, whereas membrane-associated maltogenic EUR_01860 breaks down maltooligosaccharides longer than maltotriose. The display range glycan-binding specificities ensure glucose through maltoheptaose some α1,6-branched glycans. Taken together, describe pathway for utilization by E. rectale DSM 17629 may be conserved among other starch-degrading Clostridium cluster XIVa organisms gut.