Crystal structure of a class 2 D-xylose isomerase from the human intestinal tract microbe Bacteroides thetaiotaomicron

초록

The human intestinal microbe Bacteroides thetaiotaomicron has an extensive starch utilization system and multiple genesthat are involved in starch binding and utilization. We determined the structure of a xylose isomerase (XI) of Bacteroidesthetaiotaomicron, which belongs to the class 2 XIs. Although the overall structures of XIs from different organisms werehighly similar to each other, some large deviations were found in the class 1 and class 2 XIs; the long N-terminal extensionof class 2 XIs made additional contact with the adjacent subunit of XI, and the C-terminal small α helical domain of XIsexhibited distinguishable structural features between the class 1 and class 2 XIs. However, the structures around the metaland substrate binding site were also almost identical regardless of the XI classes, suggesting common enzymologicalproperties between the class 1 and class 2 XIs.

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