2VPT

Clostridium thermocellum family 3 carbohydrate esterase

Summary for 2VPT

• Entry DOI: 10.2210/pdb2vpt/pdb
• Descriptor: LIPOLYTIC ENZYME, CALCIUM ION (3 entities in total)
• Functional Keywords: esterase, hydrolase
• Biological source: CLOSTRIDIUM THERMOCELLUM
• Total number of polymer chains: 1
• Total formula weight: 24271.80

Authors

Correia, M.A.S.,Prates, J.A.M.,Bras, J.,Fontes, C.M.G.A.,Newman, J.A.,Lewis, R.J.,Gilbert, H.J.,Flint, J.E. (deposition date: 2008-03-04, release date: 2008-05-06, Last modification date: 2024-11-13)

Primary citation

Correia, M.A.S.,Prates, J.A.M.,Bras, J.,Fontes, C.M.G.A.,Newman, J.A.,Lewis, R.J.,Gilbert, H.J.,Flint, J.E.
Crystal Structure of a Cellulosomal Family 3 Carbohydrate Esterase from Clostridium Thermocellum Provides Insights Into the Mechanism of Substrate Recognition
J.Mol.Biol., 379:64-, 2008

PubMed Abstract: 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.

PubMed: 18436237
DOI: 10.1016/J.JMB.2008.03.037

Experimental method

X-RAY DIFFRACTION (1.4 Å)