3s3u

Crystal Structure of Uncleaved ThnT T282C

spinqualitylabelsall models 3s3u, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3s3u is a 2 chain structure with sequence from "streptomyces_cattleya"_kahan_et_al._1979 "streptomyces cattleya" kahan et al. 1979. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Gene: ThnT ("Streptomyces cattleya" Kahan et al. 1979) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Publication Abstract from PubMed ThnT is a pantetheine hydrolase from the DmpA/OAT superfamily involved in the biosynthesis of the beta-lactam antibiotic thienamycin. We performed a structural and mechanistic investigation into the cis-autoproteolytic activation of ThnT, a process that has not previously been subject to analysis within this superfamily of enzymes. Removal of the gamma-methyl of the threonine nucleophile resulted in a rate deceleration that we attribute to a reduction in the population of the reactive rotamer. This phenomenon is broadly applicable and constitutes a rationale for the evolutionary selection of threonine nucleophiles in autoproteolytic systems. Conservative substitution of the nucleophile (T282C) allowed determination of a 1.6-A proenzyme ThnT crystal structure, which revealed a level of structural flexibility not previously observed within an autoprocessing active site. We assigned the major conformer as a nonreactive state that is unable to populate a reactive rotamer. Our analysis shows the system is activated by a structural rearrangement that places the scissile amide into an oxyanion hole and forces the nucleophilic residue into a forbidden region of Ramachandran space. We propose that conformational strain may drive autoprocessing through the destabilization of nonproductive states. Comparison of our data with previous reports uncovered evidence that many inactivated structures display nonreactive conformations. For penicillin and cephalosporin acylases, this discrepancy between structure and function may be resolved by invoking the presence of a hidden conformational state, similar to that reported here for ThnT. Insights into cis-autoproteolysis reveal a reactive state formed through conformational rearrangement.,Buller AR, Freeman MF, Wright NT, Schildbach JF, Townsend CA Proc Natl Acad Sci U S A. 2012 Feb 14;109(7):2308-13. Epub 2012 Jan 30. PMID:22308359 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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