3AMM

Cellotetraose complex of cellulase 12A from thermotoga maritima

Summary for 3AMM

• Entry DOI: 10.2210/pdb3amm/pdb
• Related: 3AMH 3AMN 3AMP 3AMQ
• Related PRD ID: PRD_900011
• Descriptor: Endo-1,4-beta-glucanase, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose (3 entities in total)
• Functional Keywords: beta jellyroll, glucanase, cellulose, hydrolase
• Biological source: Thermotoga maritima
• Total number of polymer chains: 2
• Total formula weight: 62892.38

Authors

Cheng, Y.-S.,Ko, T.-P.,Liu, J.-R.,Guo, R.-T. (deposition date: 2010-08-20, release date: 2011-03-16, Last modification date: 2023-11-01)

Primary citation

Cheng, Y.-S.,Ko, T.-P.,Wu, T.-H.,Ma, Y.,Huang, C.-H.,Lai, H.-L.,Wang, A.H.-J.,Liu, J.-R.,Guo, R.-T.
Crystal structure and substrate-binding mode of cellulase 12A from Thermotoga maritima
Proteins, 79:1193-1204, 2011

PubMed Abstract: Cellulases have been used in many applications to treat various carbohydrate-containing materials. Thermotoga maritima cellulase 12A (TmCel12A) belongs to the GH12 family of glycoside hydrolases. It is a β-1,4-endoglucanase that degrades cellulose molecules into smaller fragments, facilitating further utilization of the carbohydrate. Because of its hyperthermophilic nature, the enzyme is especially suitable for industrial applications. Here the crystal structure of TmCel12A was determined by using an active-site mutant E134C and its mercury-containing derivatives. It adopts a β-jellyroll protein fold typical of the GH12-family enzymes, with two curved β-sheets A and B and a central active-site cleft. Structural comparison with other GH12 enzymes shows significant differences, as found in two longer and highly twisted β-strands B8 and B9 and several loops. A unique Loop A3-B3 that contains Arg60 and Tyr61 stabilizes the substrate by hydrogen bonding and stacking, as observed in the complex crystals with cellotetraose and cellobiose. The high-resolution structures allow clear elucidation of the network of interactions between the enzyme and its substrate. The sugar residues bound to the enzyme appear to be more ordered in the -2 and -1 subsites than in the +1, +2 and -3 subsites. In the E134C crystals the bound -1 sugar at the cleavage site consistently show the α-anomeric configuration, implicating an intermediate-like structure.

PubMed: 21268113
DOI: 10.1002/prot.22953

Experimental method

X-RAY DIFFRACTION (1.98 Å)