Mechanism of Bacterial Cell-Surface Attachment Revealed by the Structure of Cellulosomal Type II Cohesin-dockerin Complex
Bacterial cell-surface attachment of macromolecular complexes maintains the microorganism in close proximity to extracellular substrates and allows for optimal uptake of hydrolytic byproducts. The cellulosome is a large multienzyme complex used by many anaerobic bacteria for the efficient degradation of plant cell-wall polysaccharides. The mechanism of cellulosome retention to the bacterial cell surface involves a calcium-mediated protein-protein interaction between the dockerin (Doc) module from the cellulosomal scaffold and a cohesin (Coh) module of cell-surface proteins located within the proteoglycan layer. Here, we report the structure of an ultra-high-affinity (K{sub a} = 1.44 x 10{sup 10} M{sup 1-}) complex between type II Doc, together with its neighboring X module from the cellulosome scaffold of Clostridium thermocellum, and a type II Coh module associated with the bacterial cell surface. Identification of X module-Doc and X module-Coh contacts reveal roles for the X module in Doc stability and enhanced Coh recognition. This extremely tight interaction involves one face of the Coh and both helices of the Doc and comprises significant hydrophobic character and a complementary extensive hydrogen-bond network. This structure represents a unique mechanism for cell-surface attachment in anaerobic bacteria and provides a rationale for discriminating between type I and type II Coh modules.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 930123
- Report Number(s):
- BNL-80768-2008-JA; TRN: US200822%%1334
- Journal Information:
- Proceedings of the National Academy of Sciences of the USA, Vol. 103
- Country of Publication:
- United States
- Language:
- English
Similar Records
Building a Foundation for Structure-Based Cellulosome Design for Cellulosic Ethanol: Insight into Cohesin-Dockerin Complexation from Computer Simulation
Purification and crystallization of a trimodular complex comprising the type II cohesin–dockerin interaction from the cellulosome of Clostridium thermocellum