Figure 6

Proposed architectures for cell-bound and cell-free cellulosome assembly in C. clariflavum . The scheme shows the possible interactions among scaffoldin and enzymatic modules, as derived from examination of interactions by affinity ELISA. Specification of scaffoldins is detailed in Figure 1. Four potential cell-anchored cellulosomal complexes are represented. Two of the complexes employ the adaptor protein ScaB to join the cell-anchored scaffoldins (ScaC and ScaJ, containing an SLH domain, and four and one type I cohesins, respectively) to the primary enzyme-integrating scaffoldins (ScaA and ScaH/L) via the type II cohesins of ScaB and XDocs of the former. The type II cohesins of ScaD (cohesins 1 and 2) and ScaF are also cell-anchored scaffoldins that bind directly ScaA or ScaH/L. The type I cohesins of ScaG and ScaD (cohesin 3) interact with type I dockerins of dockerin-bearing enzymes. ScaG is suspected to be a cell-anchored scaffoldin, based on previous studies of the copper amine-oxidase domain in the OlpC protein from C. thermocellum. ScaE has seven type II cohesins which are able to bind seven XDoc modules, thereby creating a large, cell-free cellulosomal complex. CBSM, cell surface-binding module.