Single versus dual-binding conformations in cellulosomal cohesin-dockerin complexes

Cohesins and dockerins are complementary interacting protein modules that form stable and highly specific receptor ligand complexes. They play a crucial role in the assembly of cellulose-degrading multi-enzyme complexes called cellulosomes and have potential applicability in several technology areas, including biomass conversion processes. Here, we describe several exceptional properties of cohesin dockerin complexes, including their tenacious biochemical affinity, remarkably high mechanostability and a dual-binding mode of recognition that is contrary to the conventional lock and -key model of receptor-ligand interactions. We focus on structural aspects of the dual mode of cohesin dockerin binding, highlighting recent single-molecule analysis techniques for its explicit characterization.