2b59: Difference between revisions

[[Image:2b59.gif|left|200px]]<br /><applet load="2b59" size="350" color="white" frame="true" align="right" spinBox="true"  

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(a) = 1.44 x 10(10) M(-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.

2B59 is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Clostridium_thermocellum Clostridium thermocellum] and [http://en.wikipedia.org/wiki/Clostridium_thermocellum_atcc_27405 Clostridium thermocellum atcc 27405] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2B59 OCA].  

[[Category: Adams, J J.]]

[[Category: BSGI, Montreal-Kingston Bacterial Structural Genomics Initiative.]]

[[Category: Smith, S P.]]

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