Identification of the tissue inhibitor of metalloproteinases-2 (TIMP-2) binding site on the hemopexin carboxyl domain of human gelatinase A by site-directed mutagenesis. The hierarchical role in binding TIMP-2 of the unique cationic clusters of hemopexin modules III and IV - PubMed (original) (raw)

. 1999 Feb 12;274(7):4421-9.

doi: 10.1074/jbc.274.7.4421.

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Identification of the tissue inhibitor of metalloproteinases-2 (TIMP-2) binding site on the hemopexin carboxyl domain of human gelatinase A by site-directed mutagenesis. The hierarchical role in binding TIMP-2 of the unique cationic clusters of hemopexin modules III and IV

C M Overall et al. J Biol Chem. 1999.

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Abstract

Cell surface activation of progelatinase A occurs in a quaternary complex with the tissue inhibitor of metalloproteinases-2 (TIMP-2) and two membrane-type matrix metalloproteinases. We have mutated the unique cationic clusters found in hemopexin modules III and IV of the carboxyl domain (C domain) of human gelatinase A to determine their role in binding TIMP-2. Twelve single, double, and triple site-directed mutations were produced that exhibited different TIMP-2 binding properties. Notably, single alanine substitutions at Lys547 and Lys617 reduced TIMP-2 binding by an order of magnitude from that of the recombinant wild-type C domain. Mutations that completely disrupted the C domain.TIMP-2 interaction were K558A/R561A, K610T/K617A, and K566A/K568A/K617A. A triple mutation, K566A/K568A/K575A, having TIMP-2 binding indistinguishable from the wild-type C domain (Kd 3.0 x 10(-8) M), showed that simple reduction of net positive charge does not reduce TIMP-2 affinity. Because the double mutation K566A/K568A also did not alter TIMP-2 binding, these data do not confirm previously reported chimera studies that indicated the importance of the triple lysine cluster at positions 566/567/568 in TIMP-2 binding. Nonetheless, a subtle role in TIMP-2 interaction for the 566/567/568-lysine triad is indicated from the enhanced reduction in TIMP-2 binding that occurs when mutations here were combined with K617A. Thus, these analyses indicate that the TIMP-2 binding surface lies at the junction of hemopexin modules III and IV on the peripheral rim of the gelatinase A C domain. This location implies that considerable molecular movement of the TIMP-2. C domain complex would be needed for the bound TIMP-2 to inhibit in cis the gelatinase A active site.

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