4UA8: EUR_01830 (maltotriose-binding protein) complexed with maltotriose

Eubacterium rectale is a prominent human gut symbiont yet little is known about the molecular strategies this bacterium has developed to acquire nutrients within the competitive gut ecosystem. Starch is one of the most abundant glycans in the human diet, and E. rectale increases in vivo when the host consumes a diet rich in resistant starch, although it is not a primary degrader of this glycan. Here we present the results of a quantitative proteomics study in which we identify two glycoside hydrolase 13 family enzymes, and three ABC transporter solute-binding proteins that are abundant during growth on starch and, we hypothesize, work together at the cell surface to degrade starch and capture the released maltooligosaccharides. EUR_21100 is a multidomain cell wall anchored amylase that preferentially targets starch polysaccharides, liberating maltotetraose, whereas the membrane-associated maltogenic amylase EUR_01860 breaks down maltooligosaccharides longer than maltotriose. The three solute-binding proteins display a range of glycan-binding specificities that ensure the capture of glucose through maltoheptaose and some alpha1,6-branched glycans. Taken together, we describe a pathway for starch utilization by E. rectale DSM 17629 that may be conserved among other starch-degrading Clostridium cluster XIVa organisms in the human gut.
PDB ID: 4UA8Download
MMDB ID: 125273
PDB Deposition Date: 2014/8/8
Updated in MMDB: 2014/12
Experimental Method:
x-ray diffraction
Resolution: 1.54  Å
Source Organism:
Similar Structures:
Biological Unit for 4UA8: monomeric; determined by author
Molecular Components in 4UA8
Label Count Molecule
Protein (1 molecule)
Carbohydrate ABC Transporter Substrate-binding Protein, Cut1 Family (TC 3.a.1.1.-)
Molecule annotation
Chemicals (3 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB