Structure-function relationships in tissue inhibitor of metalloproteinase -: Metalloproteinase interactions

The tissue inhibitors of metalloproteinases (TIMPs) are the major inhibitors of the matrix metalloproteinases and therefore have an important role in the regulation of extracellular matrix turnover. We have examined the interaction of the two distinct structural and functional domains of the TIMPs with the defined domain structures of individual MMPs, in order to determine their roles in the inhibitory mechanism. Mutants of the TIMPs and the matrix metalloproteinases that lack the C-terminal domain have been prepared and kinetic studies of their association carried out. The N-terminal domains of TIMP-1 and -2 are efficient inhibitors through interaction with the enzyme catalytic domains. The C-terminal domain of the TIMPs enhances their rate of inhibition of many of the enzymes, probably due to a docking effect in which binding aligns the N-terminal domain with the enzyme active site. Site-directed mutagenesis of residues within the N-terminal domain of TIMP-1 has demonstrated that no single residue is responsible for the inhibitory activity and has identified a potential site for the apposition of the TIMP C-terminal domain.