Insights into the structural determinants of cohesin-dockerin specificity revealed by the crystal structure of the type II cohesin from Clostridium thermocellum SdbA.
Article Details
- CitationCopy to clipboard
Carvalho AL, Pires VM, Gloster TM, Turkenburg JP, Prates JA, Ferreira LM, Romao MJ, Davies GJ, Fontes CM, Gilbert HJ
Insights into the structural determinants of cohesin-dockerin specificity revealed by the crystal structure of the type II cohesin from Clostridium thermocellum SdbA.
J Mol Biol. 2005 Jun 24;349(5):909-15.
- PubMed ID
- 15913653 [ View in PubMed]
- Abstract
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.