2BVL: Crystal Structure Of The Catalytic Domain Of Toxin B From Clostridium Difficile In Complex With Udp, Glc And Manganese Ion

Toxin B is a member of the family of large clostridial cytotoxins which are of great medical importance. Its catalytic fragment was crystallized in the presence of UDP-glucose and Mn2+. The structure was determined at 2.2 A resolution, showing that toxin B belongs to the glycosyltransferase type A family. However, toxin B contains as many as 309 residues in addition to the common chainfold, which most likely contribute to the target specificity. A superposition with other glycosyltransferases shows the expected positions of the acceptor oxygen atom during glucosyl transfer and indicates further that the reaction proceeds probably along a single-displacement pathway. The C1'' donor carbon atom position is defined by the bound UDP and glucose. It assigns the surface area of toxin B that forms the interface to the target protein during the modifying reaction. A docking attempt brought the known acceptor atom, Thr37 O(gamma1) of the switch I region of the RhoA:GDP target structure, near the expected position. The relative orientation of the two proteins was consistent with both being attached to a membrane. Sequence comparisons between toxin B variants revealed that the highest exchange rate occurs around the active center at the putative docking interface, presumably due to a continuous hit-and-evasion struggle between Clostridia and their eukaryotic hosts.
PDB ID: 2BVLDownload
MMDB ID: 34928
PDB Deposition Date: 2005/6/30
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 2BVL: monomeric; determined by author and by software (PQS)
Molecular Components in 2BVL
Label Count Molecule
Protein (1 molecule)
Toxin B
Molecule annotation
Chemicals (8 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB