Multidomain carbohydrate-binding proteins involved in Bacteroides thetaiotaomicron starch metabolism

Elizabeth A. Cameron, Mallory A. Maynard, Christopher J. Smith, Thomas Smith, Nicole M. Koropatkin, Eric C. Martens

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

Human colonic bacteria are necessary for the digestion of many dietary polysaccharides. The intestinal symbiont Bacteroides thetaiotaomicron uses five outer membrane proteins to bind and degrade starch. Here, we report the x-ray crystallographic structures of SusE and SusF, two outer membrane proteins composed of tandem starch specific carbohydrate-binding modules (CBMs) with no enzymatic activity. Examination of the two CBMs in SusE and three CBMs in SusF reveals subtle differences in the way each binds starch and is reflected in their Kdvalues for both high molecular weight starch and small maltooligosaccharides. Thus, each site seems to have a unique starch preference that may enable these proteins to interact with different regions of starch or its breakdown products. Proteins similar to SusE and SusF are encoded in many other polysaccharide utilization loci that are possessed by human gut bacteria in the phylum Bacteroidetes. Thus, these proteins are likely to play an important role in carbohydrate metabolism in these abundant symbiotic species. Understanding structural changes that diversify and adapt related proteins in the human gut microbial community will be critical to understanding the detailed mechanistic roles that they perform in the complex digestive ecosystem.

Original languageEnglish (US)
Pages (from-to)34614-34625
Number of pages12
JournalJournal of Biological Chemistry
Volume287
Issue number41
DOIs
StatePublished - Oct 5 2012
Externally publishedYes

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Metabolism
Starch
Carbohydrates
Polysaccharides
Bacteria
Membrane Proteins
Proteins
Bacteroidetes
Carbohydrate Metabolism
Ecosystems
Ecosystem
saccharide-binding proteins
Bacteroides thetaiotaomicron
Digestion
Molecular Weight
Molecular weight
X-Rays
X rays

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Cite this

Multidomain carbohydrate-binding proteins involved in Bacteroides thetaiotaomicron starch metabolism. / Cameron, Elizabeth A.; Maynard, Mallory A.; Smith, Christopher J.; Smith, Thomas; Koropatkin, Nicole M.; Martens, Eric C.

In: Journal of Biological Chemistry, Vol. 287, No. 41, 05.10.2012, p. 34614-34625.

Research output: Contribution to journalArticle

Cameron, Elizabeth A. ; Maynard, Mallory A. ; Smith, Christopher J. ; Smith, Thomas ; Koropatkin, Nicole M. ; Martens, Eric C. / Multidomain carbohydrate-binding proteins involved in Bacteroides thetaiotaomicron starch metabolism. In: Journal of Biological Chemistry. 2012 ; Vol. 287, No. 41. pp. 34614-34625.
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