Intermodular Linker Flexibility Revealed from Crystal Structures of Adjacent Cellulosomal Cohesins of Acetivibrio cellulolyticus

Insights into Higher-Order Organization of the Cellulosome Revealed by a Dissect-and-Build Approach: Crystal Structure of Interacting Clostridium thermocellum Multimodular Components

“…Furthermore, recent structural studies of adjacent cohesin modules from the cellulosome of Acetivibrio cellulolyticus illustrated that crystallization of cellulosomal modules with intact linker segments is possible, and that the crystal packing and linker-module interactions provide novel insights in linker dynamics, cellulosome organization, and ultrastructure. 41 The current findings indicate that the X module and the adjacent CohI 9 are separated by a 13-residue linker and do not contact one another in the CohI 9 -X-DocII:CohII complex structure. While the entire linker region in the CohI 9 -X-DocII:CohII heterodimeric complex structure was modelled from electron density, it appears to have a degree of conformational freedom based on the elevated temperature factors.…”

Modular Arrangement of a Cellulosomal Scaffoldin Subunit Revealed from the Crystal Structure of a Cohesin Dyad

“…The X-ray crystal structure of the first two type II Cohs from the A. cellulolyticus adaptor Sca (ScaB)-Coh 1 in tandem with Coh 2 and the native sixresidue intermodular linker between them (CohB1-CohB2)-was determined using the molecular replacement strategy employing the model of A. cellulolyticus type II CohB1 [Protein Data Bank (PDB) code 1ZV9] 45 and refined at 1.57-Å resolution to crystallographic R-factor and R free values of 17.8% and 22.6%, respectively. The final atomic model contains four molecules of the CohB1-CohB2 dyad in the asymmetric unit (residues 1-338 in molecule A, residues 1-341 in molecule B, residues 3-337 in molecule C, and residues 4-340 in molecule D) and 2156 water molecules.…”

“…by a crystallographic study of each of the first two Cohs in this Sca. 45 Although the structures of the individual Coh modules with the linker regions attached provide basic information regarding this critical Sca component, it would be desirable to crystallize larger multimodular Sca fragments, in order to achieve additional insight into their arrangement and interactions within the Sca subunit. In the present work, we describe the crystal structure of a type II Coh dyad with its native intervening linker from the ScaB adaptor Sca of A. cellulolyticus.…”

Molecular Architecture and Structural Transitions of a Clostridium thermocellum Mini-Cellulosome

“…9,10 Recently, a considerable effort is being made to overcome this barrier, and structures of assemblies containing two or three elements of the cellulosome have been solved. 6,8,11 Still, the structural organization of two or more cohesin modules in the context of a large segment of the cellulosome, which could shed light in the regulation of inter-cohesin flexibility within the CipA scaffold protein, is unknown. Toward addressing these questions, we have solved a 35-Å-resolution structure of a C. thermocellum mini-cellulosome containing three consecutive type-I cohesin modules that are bound to three identical catalytic subunits through their native dockerin sequences, using three-dimensional (3D) EM (Fig.…”