5n12
Crystal structure of TCE treated rPPEP-1
Structural highlights
FunctionPPEP1_CLOD6 Zinc-dependent endoprotease with a unique preference for proline residues surrounding the scissile bond. Exhibits a high preference for an asparagine at the P2 position and hydrophobic residues (Val, Ile, Leu) at the P3 position. Efficiently cleaves the LPXTG cell surface proteins CD630_28310 and CD630_32460 at multiple cleavage sites in vivo. Has a role in the regulation of C.difficile adhesion versus motility by cleaving surface adhesion proteins such as the collagen binding protein CD630_28310, and is important for efficient infection. Is also able to cleave fibronectin and fibrinogen in vitro; cleaves at the N-terminus of the beta-chain of fibrinogen. Destabilizes the fibronectin network produced by human fibroblasts. Therefore, may be important in key steps of clostridial pathogenesis by degrading extracellular matrix components associated with the gut epithelial cells. To a lesser extent, IgA1, IgA2, and human HSP 90-beta, but not HSP 90-alpha, are also substrates for the enzyme. Is not active on different collagen types, casein and gelatin.[1] [2] [3] [4] Publication Abstract from PubMedThe identification of initial lead conditions for successful protein crystallization is crucial for structural studies using X-ray crystallography. In order to reduce the number of false-negative conditions, an emerging number of fluorescence-based methods have been developed which allow more efficient identification of protein crystals and help to distinguish them from salt crystals. Detection of the native tryptophan fluorescence of protein crystals is one of the most widely used methods. However, this method can fail owing to the properties of the crystallized protein or the chemical composition of the crystallization trials. Here, a simple, fast and cost-efficient method employing 2,2,2-trichloroethanol (TCE) has been developed. It can be performed with a standard UV-light microscope and can be applied to cases in which detection of native tryptophan fluorescence fails. In four test cases this method had no effect on the diffraction properties of the crystals and no structural changes were observed. Further evidence is provided that TCE can be added to crystallization trials during their preparation, making this method compatible with high-throughput approaches. Improved protein-crystal identification by using 2,2,2-trichloroethanol as a fluorescence enhancer.,Pichlo C, Toelzer C, Chojnacki K, Ocal S, Uthoff M, Ruegenberg S, Hermanns T, Schacherl M, Denzel MS, Hofmann K, Niefind K, Baumann U Acta Crystallogr F Struct Biol Commun. 2018 May 1;74(Pt 5):307-314. doi:, 10.1107/S2053230X18005253. Epub 2018 Apr 24. PMID:29717999[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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