Differentiation of Secreted and Membrane-Type Matrix Metalloproteinase Activities Based on Substitutions and Interruptions of Triple-Helical Sequences

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• 作者：Dmitriy Minond ; Janelle L. Lauer-Fields ; Mare Cudic ; Christopher M. Overall ; Duanqing Pei ; Keith Brew ; Marcia L. Moss ; Gregg B. Fields
• 刊名：Biochemistry
• 出版年：2007
• 出版时间：March 27, 2007
• 年：2007
• 卷：46
• 期：12
• 页码：3724 - 3733
• 全文大小：158K
• 年卷期：v.46,no.12(March 27, 2007)
• ISSN：1520-4995

文摘

The turnover of the collagen triple-helical structure (collagenolysis) is a tightly regulated processin normal physiology and has been ascribed to a small number of proteases. Several members of thematrix metalloproteinase (MMPs) family possess collagenolytic activity, and the mechanisms by whichthese enzymes process triple helices are beginning to be unraveled. The present study has utilized twotriple-helical sequences to compare the cleavage-site specificities of 10 MMPs. One substrate featured acontinuous Gly-Xxx-Yyy sequence (Pro-Leu-Gly~Met-Arg-Gly), while the other incorporated aninterruption in the Gly-Xxx-Yyy repeat (Pro-Val-Asn~Phe-Arg-Gly). Both sequences were selectivelycleaved by MMP-13 while in linear form, but neither proved to be selective within a triple helix. Thissuggests that the conformational presentation of substrate sequences to a MMP active site is critical forenzyme specificity, in that activities differ when sequences are presented from an unwound triple helixversus an independent single strand. Differences in specificity between secreted and membrane-type (MT)MMPs were also observed for both sequences, where MMP-2 and MT-MMPs showed an ability tohydrolyze a triple helix at an additional site (Gly-Gln bond). Interruption of the triple helix had differenteffects on secreted MMPs and MT-MMPs, because MT-MMPs could not hydrolyze the Asn-Phe bondbut instead cleaved the triple helix closer to the C terminus at a Gly-Gln bond. It is possible that MT-MMPs have a requirement for Gly in the P₁ subsite to be able to efficiently process a triple-helical molecule.Analysis of individual kinetic parameters and activation energies indicated different substrate preferenceswithin secreted MMPs, because MMP-13 preferred the interrupted sequence, while MMP-8 showed littlediscrimination between non-interrupted and interrupted triple helices. On the basis of the present andprior studies, we can assign unique triple-helical peptidase behaviors to the collagenolytic MMPs. Suchdifferences may be significant for understanding MMP mechanisms of action and aid in the developmentof selective MMP inhibitors.