The structure of the isolated catalytic domain of diphtheria toxin at pH 5.0 was determined by X-ray crystallography at 2.5 A resolution and refined to an R-factor of 19.7%. The domain is bound to its endogenous inhibitor adenylyl(3'-->5')uridine 3'-monophosphate (ApUp) ...
The structure of the isolated catalytic domain of diphtheria toxin at pH 5.0 was determined by X-ray crystallography at 2.5 A resolution and refined to an R-factor of 19.7%. The domain is bound to its endogenous inhibitor adenylyl(3'-->5')uridine 3'-monophosphate (ApUp). The structure of this 190-residue domain, which was expressed in and isolated from Escherichia coli, is essentially identical to the structure of the catalytic domain within whole diphtheria toxin determined at pH 7.5. However, there are two adjacent surface loops (loop 66-78 and loop 169-176) that exhibit clear differences when compared to the structure of the catalytic domain in whole diphtheria toxin. Although both loops are at the surface of the protein and are relatively flexible, the chain trace is well-defined in the electron density. The main structural difference is the closer approach of loops 66-78 and 169-176. We ascribe this structural change mainly to the absence of the neighboring transmembrane domain in the isolated catalytic domain as compared to whole diphtheria toxin. We suggest that this change represents the first step of the structural transition from the catalytic domain in whole diphtheria toxin to the translocated form of the domain. The changes are described in detail, and their implications for membrane translocation are discussed.
Related Citations:
The Refined Structure of Dimeric Diphtheria Toxin at 2.0 Angstroms Resolution Bennett, M.J., Choe, S., Eisenberg, D. () To be published --: --
The Refined Structure of Monomeric Diphtheria Toxin Bennett, M.J., Eisenberg, D. () To be published --: --
Domain Swapping: Entangling Alliances between Proteins Bennett, M.J., Choe, S., Eisenberg, D. (1994) Proc Natl Acad Sci U S A 91: 3127
Three Domains for Three Functions: The Crystal Structure of Diphtheria Toxin Choe, S., Bennett, M.J., Fujii, G., Curmi, P.M.G., Kantardjeff, K.A., Collier, R.J., Eisenberg, D. (1992) Nature 357: 216
X-Ray Grade Crystals of the Enzymatic Fragment of Diphtheria Toxin Kantardjeff, K., Collier, R.J., Eisenberg, D. (1989) J Biol Chem 264: 10402
Organizational Affiliation:
Molecular Biology Institute, University of California, Los Angeles 90024-1570.
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