Unraveling enzyme discrimination during cellulosome assembly independent of cohesin–dockerin affinity

摘要: Bacterial cellulosomes are generally believed to assemble at random, like those produced by Clostridium cellulolyticum. They composed of one scaffolding protein bearing eight homologous type I cohesins that bind any the dockerins borne 62 cellulosomal subunits, thus generating highly heterogeneous complexes. In present study, heterogeneity and random assembly were evaluated with a simpler model: miniscaffoldin containing three C. cellulolyticum cellulases same bacterium cognate dockerin (Cel5A, Cel48F, Cel9G). Surprisingly, rather than expected randomized integration enzymes, minicellulosome generated only distinct types complex out 10 possible combinations, indicating preferential enzymes upon binding scaffoldin. A hybrid scaffoldin displays cohesin from thermocellum, allowing sequential was exploited further characterize this phenomenon. The initial given enzyme thermocellum found influence subsequently bound cohesin. appears be related length inter-cohesin linker. data indicate has direct on dockerin-bearing proteins will interact adjacent cohesins. Thus, despite general lack specificity cohesin-dockerin interaction within species type, bacterial not necessarily assembled random.