Interaction between a Type-II Dockerin Domain and a Type-II Cohesin Domain from Clostridium thermocellum Cellulosome

Abstract

The interaction between the type-II dockerin domain of the scaffoldin protein CipA and the type-II cohesin domain of the outer layer protein SdbA is the fundamental mechanism for anchoring the cellulosome to the cell surface of Clostridium thermocellum. We constructed and purified a dockerin polypeptide and a cohesin polypeptide, and determined affinity constants of the interaction between them by the surface plasmon resonance method. The dissociation constant (K_D) value was 1.8×10⁻⁹ M, which is a little larger than that for the combination of a type-I dockerin and a type-I cohesin.