1f9o
From Proteopedia
Crystal structure of the cellulase Cel48F from C. Cellulolyticum with the thiooligosaccharide inhibitor PIPS-IG3
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
1F9O is a Single protein structure of sequence from Clostridium cellulolyticum. 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 Fri May 2 16:04:28 2008
