Allosteric control of collagen fibril degradation by matrix metalloprotease-1

Project Summary Collagen, the most abundant human protein, provides a scaffold for cells to maintain tissue and organ integrity. Fibrillar collagen is highly resistant to proteolysis and is degraded by specific matrix metalloproteases (MMPs). The degradation of fibrillar collagen is an essential part of tissue remodeling and is involved in many normal and pathological processes. While the degradation of triple-helical collagen monomers is well-studied, degradation of native collagen fibrils remains poorly understood. Fibrils are insoluble in physiological buffers, heterogeneous, and extended substrates, making them challenging to study using standard biochemical assays. We have overcome these limitations by developing a single-molecule method to track and analyze the motion of labeled MMPs on fibrils using a home-built total internal reflection fluorescence microscope (TIRFM). We propose to study the roles of MMP1 and MMP9 in degrading type-1 collagen fibrils. MMP1 can degrade triple-helical collagen, whereas MMP9 cannot degrade triple-helical collagen significantly. However, MMP9 is upregulated in numerous skin diseases, cancer metastasis, wound, inflammation, pneumonia, and atherosclerosis. We propose to study the mechanism of fibril degradation by two important MMPs by a combination of single-molecule tracking, innovative analysis, simulations, ensemble assays, and animal studies.