Catalytic properties of the cellulose-binding endoglucanase F from Fibrobacter succinogenes S85

Abstract

The celF gene from the predominant cellulolytic ruminal bacterium Fibrobacter succinogenes encodes a 118.3-kDa cellulose-binding endoglucanase, endoglucanase F (EGF). This enzyme possesses an N-terminal cellulose-binding domain and a C-terminal catalytic domain. The purified catalytic domain displayed an activity profile typical of an endoglucanase, with high catalytic activity on carboxymethyl cellulose and barley ␤-glucan. Immunoblotting of EGF and the formerly characterized endoglucanase 2 (EG2) from F. succinogenes with antibodies prepared against each of the enzymes demonstrated that EGF and EG2 contain cross-reactive epitopes. This data in conjunction with evidence that the proteins are the same size, share a 19-residue internal amino acid sequence, possess similar catalytic properties, and both bind to cellulose allows the conclusion that celF codes for EG2.

Cellulase-free xylanases fromBacillusand other microorganisms

“…There could be other possibilities for the trace amounts of cellulolytic activities by the SSP‐34 culture supernatant. Since the cellulose binding domains (CBDs) present in some endoglucanases play an important role in cellulose hydrolysis, negligible cellulolytic activities by some xylanases can also be attributed to the presence of CBDs in these xylanases [66–72]. Although it is quite unnatural for one enzyme to have a high affinity towards a non‐specific substrate, CBDs are widely distributed in xylanases [69,73].…”

Identification of the cellulose-binding domain of Fibrobacter succinogenes endoglucanase F

“…According to information obtained from CAZy, a World Wide Web server (http://afmb.cnrs-mrs.fr/~pedro/CAZY/db.html, [17]), EGF was classi¢ed in glycosyl hydrolase family 51 (GHF 51). Malburg et al noted the uniqueness of EGF because of the lack of clear similarity between EGF and other families of glycosyl hydrolases [9]. Although it has been obvious that EGF belongs to GHF 51, the uniqueness of EGF has remained, because it is the only endoglucanase belonging to GHF 51.…”

“…EG2 was found on the surface of the bacterial cells, membrane vesicles and the boundary between the cell surface and cellulose [10]. Malburg and coworkers also showed that EGF, which was produced in E. coli, had endoglucanase activity and cellulose-binding ability [9]. The PstI-XbaI fragment of celF, encoding aa residues 600^1053 of EGF, was also expressed in E. coli.…”

“…The PstI-XbaI fragment of celF, encoding aa residues 600^1053 of EGF, was also expressed in E. coli. Because the recombinant protein showed endoglucanase activity but no cellulose-binding ability, they proposed that EGF had a similarly sized N-terminal cellulose-binding domain (CBD) and C-terminal catalytic domain (CD) [9]. However, they did not examine cellulose-binding ability of the N-terminal CBD.…”

Properties of cellulose-binding modules in endoglucanase F from Fibrobacter succinogenes S85 by means of surface plasmon resonance

“…EGF is presumed to be involved in bacterial adhesion to cellulose because it is located on the bacterial cell surface, membrane vesicles and the boundary between the cell surface and cellulose [2]. Malburg et al [4] showed that EGF has an N-terminal cellulose-binding domain (CBD). We previously reported that the N-terminal CBD has two reiterated regions that are homologous to each other in amino acid sequences and are arranged in tandem; the ¢rst of these regions binds to cellulose [5].…”