2vpt
From Proteopedia
OCA (Talk | contribs)
(New page: 200px <!-- The line below this paragraph, containing "STRUCTURE_2vpt", creates the "Structure Box" on the page. You may change the PDB parameter (which sets the PD...)
Next diff →
Revision as of 05:46, 7 May 2008
CLOSTRIDIUM THERMOCELLUM FAMILY 3 CARBOHYDRATE ESTERASE
Overview
The microbial degradation of the plant cell wall is of increasing industrial significance, exemplified by the interest in generating biofuels from plant cell walls. The majority of plant cell-wall polysaccharides are acetylated, and removal of the acetyl groups through the action of carbohydrate esterases greatly increases the efficiency of polysaccharide saccharification. Enzymes in carbohydrate esterase family 3 (CE3) are common in plant cell wall-degrading microorganisms but there is a paucity of structural and biochemical information on these biocatalysts. Clostridium thermocellum contains a single CE3 enzyme, CtCes3, which comprises two highly homologous (97% sequence identity) catalytic modules appended to a C-terminal type I dockerin that targets the esterase into the cellulosome, a large protein complex that catalyses plant cell wall degradation. Here, we report the crystal structure and biochemical properties of the N-terminal catalytic module (CtCes3-1) of CtCes3. The enzyme is a thermostable acetyl-specific esterase that exhibits a strong preference for acetylated xylan. CtCes3-1 displays an alpha/beta hydrolase fold that contains a central five-stranded parallel twisted beta-sheet flanked by six alpha-helices. In addition, the enzyme contains a canonical catalytic triad in which Ser44 is the nucleophile, His208 is the acid-base and Asp205 modulates the basic nature of the histidine. The acetate moiety is accommodated in a hydrophobic pocket and the negative charge of the tetrahedral transition state is stabilized through hydrogen bonds with the backbone N of Ser44 and Gly95 and the side-chain amide of Asn124.
About this Structure
2VPT is a Single protein structure of sequence from Clostridium thermocellum. Full crystallographic information is available from OCA.
Reference
Crystal Structure of a Cellulosomal Family 3 Carbohydrate Esterase from Clostridium thermocellum Provides Insights into the Mechanism of Substrate Recognition., Correia MA, Prates JA, Bras J, Fontes CM, Newman JA, Lewis RJ, Gilbert HJ, Flint JE, J Mol Biol. 2008 Mar 28;. PMID:18436237 Page seeded by OCA on Wed May 7 08:46:36 2008
