Structural Basis for Matrix Metalloproteinase 1-Catalyzed Collagenolysis

Abstract

The proteolysis of collagen triple-helical structure (collagenolysis) is a poorly understood yet critical physiological process. Presently, matrix metalloproteinase 1 (MMP-1) and collagen triple-helical peptide models have been utilized to characterize the events and calculate the energetics of collagenolysis via NMR spectroscopic analysis of 12 enzyme-substrate complexes. The triple-helix is bound initially by the MMP-1 hemopexin-like (HPX) domain via a four amino acid stretch (analogous to type I collagen residues 782–785). The triple-helix is then presented to the MMP-1 catalytic (CAT) domain in a distinct orientation. The HPX and CAT domains are rotated with respect to one another compared with the X-ray “closed” conformation of MMP-1. Back-rotation of the CAT and HPX domains to the X-ray closed conformation releases one chain out of the triple-helix, and this chain is properly positioned in the CAT domain active site for subsequent hydrolysis. The aforementioned steps provide a detailed, experimentally-derived, and energetically favorable collagenolytic mechanism, as well as significant insight into the roles of distinct domains in extracellular protease function.

Structural insights into triple-helical collagen cleavage by matrix metalloproteinase 1

“…We propose that mammalian collagenases do not serve merely as passive acceptors of spontaneously occurring unfolded collagen states (44,45), but they promote a local perturbation of the triple helix that facilitates collagenolysis. The recently reported NMR study supports this notion by demonstrating a weakening of the collagen interchain contacts in the complex with MMP-1 (19).…”

“…6) differs from that derived from NMR experiments (19) in that it does not require a separation of the Cat and Hpx domains. Bertini et al (19), who also used the E200A mutant of MMP-1, found that the Cat domain interacted mainly with the L chain and the Hpx domain mainly with the L and M chains.…”

“…We found that only the Gly(P1)-Leu (P1′) bond was cleaved in the peptide, as in native collagen II, and concluded that the mode of collagen binding in the crystallized complex is unproductive. A productive mode could be achieved by a substantial movement of the Cat domain relative to the Hpx domain, but this necessitates the breaking of the CatHpx interface (19). We favor an alternative mechanism that leaves the interface intact.…”

“…A number of hypotheses have been proposed to explain how collagenases may destabilize and cleave triple-helical collagen (13)(14)(15)(16), and we have experimentally demonstrated that MMP-1 unwinds triple-helical collagen locally before peptide bond hydrolysis (17,18). A recent study mapped the interaction sites in MMP-1 and in triple-helical collagen by using NMR and proposed a model of collagen binding and unwinding (19). However, because the interactions between MMP-1 and collagen were not observed directly, a number of assumptions had to be made to derive a mechanism of collagenolysis.…”

TFIIH-dependent MMP-1 overexpression in trichothiodystrophy leads to extracellular matrix alterations in patient skin

“…In TTD, we found a cell type-specific transcription overexpression of the matrix metalloproteinase 1 (MMP-1), a gene encoding a zinc-containing endopeptidase that plays a key role in physiological and pathological tissue remodeling (20)(21)(22)(23). The MMP-1 transcription up-regulation results in high secretion of the active MMP-1 enzyme and subsequent degradation of collagen type I (COL1) in cell/tissue cultures, as well as in patient skin.…”