Carbohydrate-binding modules which are one of the structural components of cellulosomes-free enzyme system involved in carbohydrate digestion were also found.
The genome of A. fumigatus Z5, which efficiently degrades plant polysaccharides, encodes approximately 529 putative carbohydrate-active enzymes (280 glycoside hydrolases, 98 glycosyltransferases, 14 polysaccharide lyases, 69 carbohydrate esterases, 58 auxiliary activities and 61 carbohydrate-binding modules), which were divided into at least 115 distinct families (Additional file 6).
Endoglucanase D (EngD) from Clostridium cellulovorans is a modular enzyme comprising an N-terminal catalytic domain and a C-terminal carbohydrate-binding module, which is attached via a flexible linker.
Similar to our findings, CBM1 was the most frequently represented carbohydrate-binding module, which was similarly fused to glycoside hydrolase families predicted to target cellulose and xylan (i.e. families GH5, GH6, GH10, GH11 and AA9) [ 34].
Lora et al. [ 46] hypothesized that the ENT of QID3 mediates cell wall binding because it resembles a module which is also present in plant bimolecular proteins [ 47- 49].
Once we turn the unit over, we can see the main communications module, which is a Sim900 GSM/GPRS module.
In addition to the catalytic modules, around 7% of CAZymes also contain the carbohydrate-binding modules (CBMs), which are the most common non-catalytic modules associated with enzymes active in cell-wall hydrolysis [ 1].
Whereas class I CDHs have supposedly a carbohydrate binding site on the DHCDH, class IIA CDHs carry a small C-terminal family 1 carbohydrate binding module (CBM1), which is missing in class IIB CDHs.
The degrading activity of EG is largely supported by the carbohydrate-binding module (CBM), which is matched to the cellulose in each biomass (Ståhlberg et al. [1991]).
Such modular CAZymes in which the catalytic module and the CBM do not target the same polysaccharide have already been observed in the context of plant cell walls, notably cellulose-binding CBMs which are often components of enzymes that hydrolyze xylans, mannans, and pectins39.
