Type I dockerin repeat domain. Bacterial cohesin domains bind to a complementary protein domain named dockerin, and this interaction is required for the formation of the cellulosome, a cellulose-degrading complex. The cellulosome consists of scaffoldin, a noncatalytic scaffolding polypeptide, that comprises repeating cohesion modules and a single carbohydrate-binding module (CBM). Specific calcium-dependent interactions between cohesins and dockerins appear to be essential for cellulosome assembly. This subfamily represents type I dockerins, which are responsible for anchoring a variety of enzymatic domains to the complex.
Dockerin type I repeat. The dockerin repeat is the binding partner of the cohesin domain pfam00963. The cohesin-dockerin interaction is the crucial interaction for complex formation in the cellulosome. The dockerin repeats, each bearing homology to the EF-hand calcium-binding loop bind calcium.
PDZ domain of trypsin-like serine proteases, such as DegP/HtrA, which are oligomeric proteins involved in heat-shock response, chaperone function, and apoptosis. May be responsible for substrate recognition and/or binding, as most PDZ domains bind C-terminal polypeptides, though binding to internal (non-C-terminal) polypeptides and even to lipids has been demonstrated. In this subfamily of protease-associated PDZ domains a C-terminal beta-strand forms the peptide-binding groove base, a circular permutation with respect to PDZ domains found in Eumetazoan signaling proteins.
Dockerin repeat domain. Dockerins are modules in the cellulosome complex that often anchor catalytic subunits by binding to cohesin domains of scaffolding proteins. Three types of dockerins and their corresponding cohesin have been described in the literature. This alignment models two consecutive dockerin repeats, the functional unit.