Interrupted catalytic domain structures in xylanases from two distantly related strains of Prevotella ruminicola.

Two xylanases from the rumen anaerobic bacterium Prevotella ruminicola were found to possess highly unusual structures in which family 10 catalytic domains are interrupted by unrelated sequences. XynC from P. ruminicola B(1)4 carries a 160 amino-acid insertion, while a P. ruminicola D31d xylanase carries an unrelated region of 280 amino acids, containing an imperfect 130 amino-acid duplication. Both regions of family 10 similarity were shown to be essential for activity of the D31d enzyme.