Elastin degradation by cathepsin V requires two exosites

Area of Science:

• Biochemistry
• Protease Function
• Extracellular Matrix Degradation

Background:

• Cathepsin V is a potent elastase involved in extracellular matrix degradation.
• Its precise mechanism of action, particularly in elastinolysis, is not fully understood.
• Cathepsin L, a homolog of Cathepsin V, shows minimal elastolytic activity, suggesting specific structural differences.

Purpose of the Study:

• To identify the specific structural domains responsible for the elastolytic activity of Cathepsin V.
• To elucidate the mechanism by which Cathepsin V degrades elastin.

Main Methods:

• Generation of 11 chimeric constructs between Cathepsin V and Cathepsin L.
• Assessing the elastolytic activity of these chimeric proteases.
• Site-directed mutagenesis to investigate the role of specific exosites.

Main Results:

• Two exosites, located in surface loop regions distant from the active site, were identified as crucial for Cathepsin V's elastolytic activity.
• Replacing either exosite 1 or 2 with Cathepsin L residues significantly reduced elastolytic activity (75% and 43%, respectively).
• Replacing both exosites rendered the chimera inactive against elastin, similar to Cathepsin L.

Conclusions:

• Specific exosites on Cathepsin V, distinct from its active cleft, are essential for its potent elastolytic function.
• Understanding these exosites can guide the development of targeted inhibitors for cysteine cathepsins.
• This research provides insights into selective protease inhibition without affecting other physiological functions.