2bm3: Difference between revisions

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.

[[Category: Carvalho, A L.]]

[[Category: Davies, G J.]]

[[Category: Ferreira, L M.A.]]

[[Category: Fontes, C M.G A.]]

[[Category: Gilbert, H J.]]

[[Category: Gloster, T M.]]

[[Category: Pires, V M.R.]]

[[Category: Prates, J A.M.]]

[[Category: Proctor, M R.]]

[[Category: Romao, M J.]]

[[Category: Turkenburg, J P.]]

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