1F5J

CRYSTAL STRUCTURE OF XYNB, A HIGHLY THERMOSTABLE BETA-1,4-XYLANASE FROM DICTYOGLOMUS THERMOPHILUM RT46B.1, AT 1.8 A RESOLUTION

Summary for 1F5J

• Entry DOI: 10.2210/pdb1f5j/pdb
• Descriptor: BETA-1,4-XYLANASE, SULFATE ION (3 entities in total)
• Functional Keywords: xylanase, beta-barrel, hydrolase
• Biological source: Dictyoglomus thermophilum
• Total number of polymer chains: 2
• Total formula weight: 44812.87

Authors

McCarthy, A.A.,Baker, E.N. (deposition date: 2000-07-26, release date: 2000-11-15, Last modification date: 2024-02-07)

Primary citation

McCarthy, A.A.,Morris, D.D.,Bergquist, P.L.,Baker, E.N.
Structure of XynB, a highly thermostable beta-1,4-xylanase from Dictyoglomus thermophilum Rt46B.1, at 1.8 A resolution.
Acta Crystallogr.,Sect.D, 56:1367-1375, 2000

PubMed Abstract: Microorganisms employ a large array of enzymes to break down the cellulose and hemicelluloses of plant biomass. These enzymes, especially those with high thermal stability, have many uses in biotechnology. We have solved the crystal structure of a beta-1, 4-xylanase, XynB, from the extremely thermophilic bacterium Dictyoglomus thermophilum, isolate Rt46B.1. The protein crystallized from 1.6 M ammonium sulfate, 0.2 M HEPES pH 7.2 and 10% glycerol, with unit-cell parameters a = b = 91.3, c = 44.9 A and space group P4(3). The structure was solved at high resolution (1.8 A) by X-ray crystallography, using the method of isomorphous replacement with a single mercury derivative, and refined to a final R factor of 18.3% (R(free) = 22.1%). XynB has the single-domain fold typical of family 11 xylanases, comprising a jelly roll of two highly twisted beta-sheets that create a deep substrate-binding cleft. The two catalytic residues, Glu90 and Glu180, occupy this cleft. Compared with other family 11 xylanases, XynB has a greater proportion of polar surface and has a slightly extended C-terminus that, combined with the extension of beta-strand A5, gives additional hydrogen bonding and hydrophobic packing. These factors may account for the enhanced thermal stability of the enzyme.

PubMed: 11053833
DOI: 10.1107/S0907444900009896

Experimental method

X-RAY DIFFRACTION (1.8 Å)