SusG: A Unique Cell-Membrane-Associated α-Amylase from a Prominent Human Gut Symbiont Targets Complex Starch Molecules

Nicole M. Koropatkin, Thomas J. Smith

Research output: Contribution to journalArticle

81 Scopus citations

Abstract

SusG is an α-amylase and part of a large protein complex on the outer surface of the bacterial cell and plays a major role in carbohydrate acquisition by the animal gut microbiota. Presented here, the atomic structure of SusG has an unusual extended, bilobed structure composed of amylase at one end and an unprecedented internal carbohydrate-binding motif at the other. Structural studies further demonstrate that the carbohydrate-binding motif binds maltooligosaccharide distal to, and on the opposite side of, the amylase catalytic site. SusG has an additional starch-binding site on the amylase domain immediately adjacent to the active cleft. Mutagenesis analysis demonstrates that these two additional starch-binding sites appear to play a role in catabolism of insoluble starch. However, elimination of these sites has only a limited effect, suggesting that they may have a more important role in product exchange with other Sus components.

Original languageEnglish (US)
Pages (from-to)200-215
Number of pages16
JournalStructure
Volume18
Issue number2
DOIs
StatePublished - Feb 10 2010
Externally publishedYes

Keywords

  • MICROBIO
  • PROTEINS

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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