Allosteric communications between domains modulate the activity of matrix metalloprotease-1
Authors: Kumar Lokender , Nash Anthony , Harms Chase , Planas-Iglesias Joan , Wright Derek , Klein-Seetharaman Judith , Sarkar Susanta K. 
Published: October 2019

An understanding of the structure-dynamics relationship is essential for understanding how a protein works. Prior research has shown that the activity of a protein correlates with intra-domain dynamics occurring at picosecond to millisecond timescales. However, the correlation between inter-domain dynamics and the function of a protein is poorly understood. Here we show that communications between the catalytic and hemopexin domains of matrix metalloprotease-1 (MMP1) on type-1 collagen fibrils correlate with its activity. Using single-molecule FRET (smFRET), we identified functionally relevant open conformations where the two MMP1 domains are well-separated, which were significantly absent for catalytically inactive point mutant (E219Q) of MMP1 and could be modulated by an inhibitor or an enhancer of activity. The observed relevance of open conformations resolves the debate about the roles of open and closed MMP1 structures in function. A sum of two Gaussians fitted histograms, whereas an exponential fitted autocorrelations of smFRET values. We used a two-state Poisson process to describe the dynamics and used histograms and autocorrelations of conformations to calculate the kinetic rates between the two states. All-atom and coarse-grained simulations reproduced some of the experimental features and revealed substrate-dependent MMP1 dynamics. Our results suggest that an inter-domain separation facilitates opening up the catalytic pocket so that the collagen chains come closer to the MMP1 active site. Coordination of functional conformations at different parts of MMP1 occurs via allosteric communications that can take place via interactions mediated by collagen even if the linker between the domains is absent. Modeling dynamics as a Poisson process enables connecting the picosecond timescales of molecular dynamics simulations with the millisecond timescales of single molecule measurements. Water-soluble MMP1 interacting with water-insoluble collagen fibrils poses challenges for biochemical studies that the single molecule tracking can overcome for other insoluble substrates. Inter-domain communications are likely important for multidomain proteins.

Statement of Significance

It is often challenging to distinguish functionally important dynamics because proteins are inherently flexible. MMP1 is a model enzyme because both the catalytic and hemopexin domains are necessary to degrade triple-helical type-1 collagen, the highly proteolysis-resistant structural component of the extracellular matrix. We report, for the first time, measurements of MMP1 inter-domain dynamics on type-1 collagen fibrils. We have identified functionally relevant MMP1 conformations where the two domains are far apart. Mutations and ligands can allosterically modulate the dynamics that correlate with activity. The dynamics follow a two-state Poisson process that connects the picosecond timescales of MD simulations with the millisecond timescales of experiments. The two domains can functionally communicate via collagen even when the physical linker is absent.