2BM3: Structure Of The Type Ii Cohesin From Clostridium Thermocellum Sdba

The plant cell wall degrading enzymes expressed by anaerobic microorganisms form large multienzyme complexes (cellulosomes). Cellulosomes assemble by the Type I dockerins on the catalytic subunits binding to the reiterated Type I cohesins in the molecular scaffold, while Type II dockerin-cohesin interactions anchor the complex onto the bacterial cell surface. Type I and Type II cohesin, dockerin pairs show no cross-specificity. Here we report the crystal structure of the Type II cohesin (CohII) from the Clostridium thermocellum cell surface anchoring protein SdbA. The protein domain contains nine beta-strands and a small alpha-helix. The beta-strands assemble into two elongated beta-sheets that display a typical jelly roll fold. The structure of CohII is very similar to Type I cohesins, and the dockerin binding site, which is centred at beta-strands 3, 5 and 6, is likely to be conserved in the two proteins. Subtle differences in the topology of the binding sites and a lack of sequence identity in the beta-strands that comprise the core of the dockerin binding site explain why Type I and Type II cohesins display such distinct specificities for their target dockerins.
PDB ID: 2BM3Download
MMDB ID: 86818
PDB Deposition Date: 2005/3/9
Updated in MMDB: 2010/12
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 2BM3: monomeric; determined by author and by software (PQS)
Molecular Components in 2BM3
Label Count Molecule
Protein (1 molecule)
Scaffolding Dockerin Binding Protein a
Molecule annotation
Chemicals (4 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB