Utilization of a Novel Recombinant Myoglobin Fusion Protein Expression System to Characterize the Tissue Inhibitor of Metalloproteinase (TIMP)-4 and TIMP-2 C-terminal Domain and Tails by Mutagenesis

• Published in: The Journal of biological chemistry 2002-12, Vol.277 (50), p.48696-48707
• Main Authors: Kai, Heidi S.-T., Butler, Georgina S., Morrison, Charlotte J., King, Angela E., Pelman, Gayle R., Overall, Christopher M.
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M209177200

Tissue inhibitor of metalloproteinase (TIMP)-4 binds pro-matrix metalloproteinase (MMP)-2 and efficiently inhibits MT1-MMP, but unlike TIMP-2 neither forms a trimolecular complex nor supports pro-MMP-2 activation. To investigate the structural and functional differences between these two TIMPs, the C-terminal domains (C-TIMP-4 and C-TIMP-2) were expressed independently from their N domains and mutations were introduced into the C-terminal tails. Myoglobin was used as a novel recombinant fusion protein partner because spectroscopic measurement of the heme Soret absorbance at 408 nm readily enabled calculation of the molar equivalent of the red-colored recombinant protein, even in complex protein mixtures. Both C-TIMP-4 and C-TIMP-2 bound pro-MMP-2 and blocked concanavalin A-induced cellular activation of the enzyme. Measurement of k on rates revealed that the inhibition of MMP-2 by TIMP-4 is preceded by a C domain docking interaction, but in contrast to TIMP-2, this is not enhanced by a C-terminal tail interaction and so occurs at a slower rate. Indeed, the binding stability of C-TIMP-4 was unaltered by deletion of the C-terminal tail, but replacement with the tail of TIMP-2 increased its affinity for pro-MMP-2 by ∼2-fold, as did substitution with the TIMP-2 C-terminal tail acidic residues in the tail of C-TIMP-4 (V193E/Q194D). Conversely, substitution of the C-terminal tail of C-TIMP-2 with that of TIMP-4 reduced pro-MMP-2 binding by ∼75%, as did reduction of its acidic character by mutation to the corresponding TIMP-4 amino acid residues (E192V/D193Q). Together, this shows the importance of Glu 192 and Asp 193 in TIMP-2 binding to pro-MMP-2; the lack of these acidic residues in the TIMP-4 C-terminal tail, which reduces the stability of complex formation with the MMP-2 hemopexin C domain, probably precludes TIMP-4 from supporting the activation of pro-MMP-2.