3h7d | pdb_00003h7d
The crystal structure of the cathepsin K Variant M5 in complex with chondroitin-4-sulfate
Structural highlights
DiseaseCATK_HUMAN Defects in CTSK are the cause of pycnodysostosis (PKND) [MIM:265800. PKND is an autosomal recessive osteochondrodysplasia characterized by osteosclerosis and short stature.[1] [2] [3] [4] FunctionCATK_HUMAN Closely involved in osteoclastic bone resorption and may participate partially in the disorder of bone remodeling. Displays potent endoprotease activity against fibrinogen at acid pH. May play an important role in extracellular matrix degradation. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedIn the presence of oligomeric chondroitin 4-sulfate (C4-S), cathepsin K (catK) forms a specific complex that was shown to be the source of the major collagenolytic activity in bone osteoclasts. C4-S forms multiple contacts with amino acid residues on the backside of the catK molecule that help to facilitate complex formation. As cathepsin L does not exhibit a significant collagenase activity in the presence or in the absence of C4-S, we substituted the C4-S interacting residues in catK with those of cathepsin L. Variants revealed altered collagenolytic activities with the largest inhibitory effect shown by the hexavariant M5. None of the variants showed a reduction in their gelatinolytic and peptidolytic activities when compared with wild-type catK, indicating no structural alteration within their active sites. However, the crystal structure of the M5 variant in the presence of oligomeric C4-S revealed a different binding of chondroitin 4-sulfate. C4-S is not continuously ordered as it is in the wild-type catK.C4-S complex. The orientation and the direction of the hexasaccharide on the catK surface have changed, so that the hexasaccharide is positioned between two symmetry-related molecules. Only one M5 variant molecule of the dimer that is present in the asymmetric unit interacts with C4-S. These substitutions have changed the mode of catK binding to C4-S and, as a result, have likely affected the collagenolytic potential of the variant. The data presented here support our hypothesis that distinct catK/C4-S interactions are necessary for the collagenolytic activity of the enzyme. Structure-activity analysis of cathepsin K/chondroitin 4-sulfate interactions.,Cherney MM, Lecaille F, Kienitz M, Nallaseth FS, Li Z, James MN, Bromme D J Biol Chem. 2011 Mar 18;286(11):8988-98. Epub 2010 Dec 30. PMID:21193413[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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