Conformational selection and collagenolysis in type III collagen

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Biology

Background:

• Matrix metalloproteinases (MMPs) are enzymes that degrade extracellular matrix components, including collagen.
• Collagen has multiple potential cleavage sites, but MMPs typically cleave native collagen at a single specific site.
• Previous research indicated non-catalytic MMP domains aid localization to collagen cleavage sites.

Purpose of the Study:

• To investigate the role of catalytic site binding in determining the specificity of MMP collagen cleavage.
• To determine if MMP active site complementarity influences which collagen cleavage site is targeted.

Main Methods:

• Computed the conformational free energy landscape of Type III collagen at various potential cleavage sites.
• Analyzed the sampling of unfolded states and their complementarity to the MMP catalytic site.

Main Results:

• Potential cleavage sites sample unfolded states, but the true cleavage site exhibits structures complementary to the MMP catalytic site.
• Non-cleaved sites sample conformations incompatible with the MMP active site.
• Arginine residues play a role in the structural stability of collagen near the cleavage site.

Conclusions:

• MMP specificity is determined by the complementarity between the enzyme's catalytic site and locally unfolded collagen structures.
• The true cleavage site in Type III collagen samples an ensemble of unfolded states uniquely suited for MMP binding.
• Arginine residues contribute to the precise structural modulation required for specific MMP-collagen interaction.