Remote Exosites of the Catalytic Domain of Matrix Metalloproteinase-12 Enhance Elastin Degradation

摘要: How does matrix metalloproteinase-12 (MMP-12 or metalloelastase) degrade elastin with high specific activity? Nuclear magnetic resonance suggested soluble covers surfaces of MMP-12 far from its active site. Two these have been found, by mutagenesis guided the BINDSIght approach, to affect degradation and affinity for substrates but not a small peptide substrate. Main exosite 1 has extended Asp124 that binds calcium. Novel 2 comprises residues II-III loop β-strand I near back catalytic domain. The degree exposure distal exosites may make them accessible made more flexible partial hydrolysis. Importantly, combination one lesion each at site decreased competence toward 13-18-fold level MMP-3, homologue poor elastase. Double-mutant cycle analysis conservative mutations Met156 (exosite 2) either 1) Ile180 (active site) showed they had additive effects. Compared polar substitutions observed in other MMPs, enhanced k(cat) elastin. Both detracted higher folding stability mutations. This resembles trend enzymes an inverse relationship between activity. Restoring mutants In degradation, contributed manner independent site, coupling Ala182 concept weak, separated interactions coalescing somewhat independently can be this proteolytic digestion protein fibrils.