Function of the Family-9 and Family-22 Carbohydrate-Binding Modules in a Modular β-1,3-1,4-Glucanase/Xylanase Derived fromClostridium stercorariumXyn10B

Abstract

Clostridium stercorarium Xyn10B having hydrolytic activities on xylan and -1,3-1,4-gllucan is a modular enzyme composed of two family-22 carbohydrate-binding modules (CBMs), a family-10 catalytic module of the glycoside hydrolases, a family-9 CBM, and two S-layer homologous modules, consecutively from the N-terminus. We investigated the function of family-9 and family-22 CBMs in a modular enzyme by comparing the enzymatic properties of a truncated enzyme composed of two family-22 CBMs and the catalytic module (rCBM22-CM), an enzyme composed of the catalytic module and family-9 CBM (rCM-CBM9), an enzyme composed of two family-22 CBMs, the catalytic module, and family-9 CBM (rCBM22-CM-CBM9), and the catalytic module polypeptide (rCM). Although the addition of family-9 CBM to rCM and rCBM22-CM did not significantly change catalytic activity toward xylan and -1,3-1,4-glucan, the addition of family-22 CBM to rCM and rCM-CBM9 drastically enhanced catalytic activity toward xylan and especially -1,3-1,4-glucan. Furthermore, the addition of family-22 CBM to rCM and rCM-CBM9 shifted the optimum temperature from 65 C to 75 C, but that of family-9 CBM to rCM and rCBM22-CM did not affect the optimum temperature. These facts suggest that the enzyme properties of Xyn10B were mainly dependent on the presence of the family-22 CBMs but not family-9 CBM.

Influence of transposition and insertion of additional binding domain on expression and characteristics of xylanase C of Clostridium thermocellum

“…Although in general similar patterns of relative activities of these enzymes were observed against oat spelt xylan and pretreated bagasse, but against pretreated biomass the specific activity of XynC-BCB was three fold higher as compared to that of XynC-BC (Table 2) These results show that the binding domain whether attached to the N-or C-terminal of the catalytic domain enhances activity to the same level, whereas the binding domain at both the termini results in further increase in activity. The role of the binding domain belonging to family 22 in facilitating the catalytic domain to bind to the substrate seems to be important for activity as reported previously (Zhao et al, 2005).…”

Truncated derivatives of a multidomain thermophilic glycosyl hydrolase family 10 xylanase from Thermotoga maritima reveal structure related activity profiles and substrate hydrolysis patterns

“…From these results, one can conclude that N-or C-terminal accessory domains can make proteins less susceptible to heat, as reported before for other thermophilic or even mesophilic xylanases (Abou-Hachem et al, 2003;Ali et al, 2005;Blanco et al, 1999;Sunna et al, 2000a,b;Zhao et al, 2005). As stated above, the resistance against thermoinactivation of the XTMA catalytic domain is not only the result of a single domain, but is also affected by inter-domain interactions.…”

Distinct Roles for Carbohydrate-Binding Modules of Glycoside Hydrolase 10 (GH10) and GH11 Xylanases from Caldicellulosiruptor sp. Strain F32 in Thermostability and Catalytic Efficiency

“…A number of previous results for GH10 xylanases indicated that N-or C-terminal accessory module absence can reduce the thermal stability to the same extent as XynB from Caldicellulosiruptor sp. strain F32 (Table 2) (20,21,44,45). To date, only three crystal structures of GH10 xylanases have been reported together with CBMs, i.e., Cellvibrio japonicus Xyn10C (CjXyn10C; Protein Data Bank entries 1US2 and 1US3) (46), Streptomyces olivaceoviridis Xyn (SoXyn; Protein Data Bank entry 1ISV) (22,47), and Clostridium thermocellum (CtXyn10B; Protein Data Bank entry 2W5F) (6).…”