Molecular insights into substrate specificity and thermal stability of a bacterial GH5-CBM27 endo-1,4-beta-D-mannanase

作者：dos Santos Camila Ramos; Paiva Joice Helena; Meza Andreia Navarro; Cota Junio; Alvarez Thabata Maria; Ruller Roberto; Prade Rolf Alexander; Squina Fabio Marcio; Murakami Mario Tyago^*

来源：Journal of Structural Biology, 2012, 177(2): 469-476.

DOI：10.1016/j.jsb.2011.11.021

• Mannan endo-1,4-beta-mannosidase
• Glycoside hydrolase family 5
• Carbohydrate binding module 27
• Thermotoga petrophila RKU-1
• Crystal structure
• Substrate recognition

The breakdown of beta-1,4-mannoside linkages in a variety of mannan-containing polysaccharides is of great importance in industrial processes such as kraft pulp delignification, food processing and production of second-generation biofuels, which puts a premium on studies regarding the prospection and engineering of beta-mannanases. In this work, a two-domain beta-mannanase from Thermotoga petrophila that encompasses a GH5 catalytic domain with a C-terminal CBM27 accessory domain, was functionally and structurally characterized. Kinetic and thermal denaturation experiments showed that the CBM27 domain provided thermo-protection to the catalytic domain, while no contribution on enzymatic activity was observed. The structure of the catalytic domain determined by SIRAS revealed a canonical (alpha/beta)(8)-barrel scaffold surrounded by loops and short helices that form the catalytic interface. Several structurally related ligand molecules interacting with TpMan were solved at high-resolution and resulted in a wide-range representation of the subsites forming the active-site cleft with residues W134, E198, R200, E235, H283 and W284 directly involved in glucose binding.

• 出版日期2012-2