1fbw
From Proteopedia
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Crystal structure of the cellulase CEL48F from C. cellulolyticum in complex with cellohexaose
Overview
Cellulase Cel48F from Clostridium cellulolyticum was described as a, processive endo-cellulase. The active site is composed of a 25 A long, tunnel which is followed by an open cleft. During the processive action, the cellulose substrate has to slide through the tunnel to continuously, supply the leaving group site with sugar residues after the catalytic, cleavage. To study this processive action in the tunnel, the native, catalytic module of Cel48F and the inactive mutant E55Q, have been, cocrystallized with cellobiitol, two thio-oligosaccharide inhibitors, (PIPS-IG3 and IG4) and the cello-oligosaccharides cellobiose, -tetraose, and -hexaose. Seven sub-sites in the tunnel section of the active center, could be identified and three of the four previously reported sub-sites in, the open cleft section were reconfirmed. The sub-sites observed for the, thio-oligosaccharide inhibitors and oligosaccharides, respectively, were, located at two different positions in the tunnel corresponding to a shift, in the chain direction of about a half sugar subunit. These two positions, have different patterns of stacking interactions with aromatic residues, present in the tunnel. Multiple patterns are not observed in nonprocessive, endo-cellulases, where only one sugar position is favored by aromatic, stacking. It is therefore proposed that the aromatic residues serve as, lubricating agents to reduce the sliding barrier in the processive action.
About this Structure
1FBW is a Single protein structure of sequence from Clostridium cellulolyticum with CA as ligand. Active as Cellulase, with EC number 3.2.1.4 Full crystallographic information is available from OCA.
Reference
Crystal structures of the cellulase Cel48F in complex with inhibitors and substrates give insights into its processive action., Parsiegla G, Reverbel-Leroy C, Tardif C, Belaich JP, Driguez H, Haser R, Biochemistry. 2000 Sep 19;39(37):11238-46. PMID:10985769
Page seeded by OCA on Tue Nov 20 14:48:20 2007
