The S2 subsites of cathepsins K and L and their contribution to collagen degradation.
The exchange of residues 67 and 205 of the S2 pocket of human cysteine cathepsins K and L induces a permutation of their substrate specificity toward fluorogenic peptide substrates. While the cathepsin L-like cathepsin K (Tyr67Leu/Leu205Ala) mutant has a marked preference for Phe, the Leu67Tyr/Ala205Leu cathepsin L variant shows an effective cathepsin K-like preference for Leu and Pro. A similar turnaround of inhibition was observed by using specific inhibitors of cathepsin K [1-(N-Benzyloxycarbonyl-leucyl)-5-(N-Boc-phenylalanyl-leucyl)carbohydrazide] and cathepsin L [N-(4-biphenylacetyl)-S-methylcysteine-(D)-Arg-Phe-beta-phenethylamide]. Molecular modeling studies indicated that mutations alter the character of both S2 and S3 subsites, while docking calculations were consistent with kinetics data. The cathepsin K-like cathepsin L was unable to mimic the collagen-degrading activity of cathepsin K against collagens I and II, DQ-collagens I and IV, and elastin-Congo Red. In summary, double mutations of the S2 pocket of cathepsins K (Y67L/L205A) and L (L67Y/A205L) induce a switch of their enzymatic specificity toward small selective inhibitors and peptidyl substrates, confirming the key role of residues 67 and 205. However, mutations in the S2 subsite pocket of cathepsin L alone without engineering of binding sites to chondroitin sulfate are not sufficient to generate a cathepsin K-like collagenase, emphasizing the pivotal role of the complex formation between glycosaminoglycans and cathepsin K for its unique collagenolytic activity.
Lecaille
Fabien
F
INSERM, U 618, Tours, F-37000, France.
Chowdhury
Shafinaz
S
Purisima
Enrico
E
Brömme
Dieter
D
Lalmanach
Gilles
G
D056657:Cathepsin K; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003094:Collagen / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D006868:Hydrolysis; D013379:Substrate Specificity
D015853:Cysteine Proteinase Inhibitors; D003094:Collagen; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L; C534130:CTSK protein, human; D056657:Cathepsin K