Crystallographic analysis of family 11 endo-beta-1,4-xylanase Xyl1 from Streptomyces sp. S38

Family 11 endo-beta-1,4-xylanases degrade xylan, the main constituent of plant hemicelluloses, and have many potential uses in biotechnology. The structure of Xyl1, a family 11 endo-xylanase from Streptomyces sp. S38, has been solved. The protein crystallized from ammonium sulfate in the trigonal space group P321, with unit-cell parameters a = b = 71.49, c = 130.30 A, gamma = 120.0 degrees. The structure was solved at 2.0 A by X-ray crystallography using the molecular-replacement method and refined to a final R factor of 18.5% (R(free) = 26.9%). Xyl1 has the overall fold characteristic of family 11 xylanases, with two highly twisted beta-sheets defining a long cleft containing the two catalytic residues Glu87 and Glu177.