1jjf

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spinqualitylabelsall models 1jjf, resolution 1.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

STRUCTURAL BASIS FOR THE SUBSTRATE SPECIFICITY OF THE FERULOYL ESTERASE DOMAIN OF THE CELLULOSOMAL XYLANASE Z OF CLOSTRIDIUM THERMOCELLUM

Overview

Feruloyl esterases function in the cleavage of ferulic acid's bonds to, arabinoxylan and pectin where the ferulic acid moieties cross-link the, layers of polysaccharide chains within hemicellulose. This work presents, the crystal structure of FAE_XynZ, the domain of Clostridium, thermocellum's cellulosomal xylanase Z that displays feruloyl esterase, activity. The structure was obtained via multiple isomorphous replacement, with anomalous scattering (MIRAS) using three heavy atom derivatives and, refined against X-ray diffraction data of up to 1.75 A resolution. The, R-value of the final model was 0.187 (R(free) = 0.21). FAE_XynZ displays, an eight-stranded alpha/beta-fold with the characteristic "catalytic, triad" at the heart of the active site. To define the substrate, specificity determinants of the enzyme, the crystal structures of FAE_XynZ, and the inactive FAE_XynZ(S172A) mutant were determined in complexes with, the feruloyl-arabinoxylans FAXX and FAX(3), respectively. In the complex, crystals, the ferulic acid moieties are clearly recognizable and allowed, identification of the hydrophobic binding pocket. The carbohydrate part of, both substrates is not visible in either structure. The location of the, putative carbohydrate binding-pocket was inferred based on the location, and orientation of the adjacent ferulic acid molecule. Five of the six, residues lining the pocket were found to be conserved in FAE A from, Orpinomyces sp., which further supports the proposed role of these amino, acids.

About this Structure

1JJF is a Single protein structure of sequence from Clostridium thermocellum with PT as ligand. Active as Endo-1,4-beta-xylanase, with EC number 3.2.1.8 Full crystallographic information is available from OCA.

Reference

Structural basis for the substrate specificity of the feruloyl esterase domain of the cellulosomal xylanase Z from Clostridium thermocellum., Schubot FD, Kataeva IA, Blum DL, Shah AK, Ljungdahl LG, Rose JP, Wang BC, Biochemistry. 2001 Oct 23;40(42):12524-32. PMID:11601976

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