MT1-MMP-TIMP-1 complex

<StructureSection load='M1.pdb' size='350' side='right' scene='MT1-MMP-TIMP-1_complex/Cv2/8' caption=''>

{{Clear}}

The human matrix metalloproteinases (MMPs) family comprises a large group of structurally homologous zinc-dependent endopeptidases (''e.g.'' <scene name='MT1-MMP-TIMP-1_complex/Cv2/9'>membrane type-1 matrix metalloproteinase (MT1-MMP)</scene> <font color='darkmagenta'><b>(darkmagenta)</b></font> and <scene name='MT1-MMP-TIMP-1_complex/Cv/14'>membrane type-3 matrix metalloproteinase (MT3-MMP)</scene> <font color='magenta'><b>(magenta)</b></font>, <scene name='MT1-MMP-TIMP-1_complex/Cv2/10'>click to see structural comparison</scene>) that perform a wide variety of biological roles. In general, the MMPs are inhibited unselectively by all four known tissue inhibitors of metalloproteinases (TIMPs 1-4) which have 40-50% sequence identity. For example, <scene name='MT1-MMP-TIMP-1_complex/Cv/14'>membrane type-3 matrix metalloproteinase (MT3-MMP)</scene> can form complex with <scene name='MT1-MMP-TIMP-1_complex/Cv/12'>wild-type TIMP-1</scene> ([[1uea]], <font color='orange'><b>colored orange</b></font>). <scene name='MT1-MMP-TIMP-1_complex/Cv/13'>The WT-TIMP-1 binding interface</scene> <font color='cyan'><b>(cyan)</b></font> is mainly composed of the N-terminal segment that approaches the active site, the AB loop (Thr33-Tyr35), the CD loop (Ala65-Cys70), and the EF loop (Thr97-Ser100). The pivotal residue, threonine 98 (Thr98), is shown as <font color='red'><b>red sticks</b></font>. In general, <scene name='MT1-MMP-TIMP-1_complex/Cv1/2'>five main chain hydrogen bonds</scene> (Cys1-Ser68, Val69-Met66, Gly71-Met66, Cys70-Glu67, and Cys70-Thr98) are intimately involved in the conformational stability of TIMP binding interface when bound to MMP.

<scene name='MT1-MMP-TIMP-1_complex/Cv2/9'>Membrane type-1 matrix metalloproteinase (MT1-MMP)</scene> <font color='darkmagenta'><b>(darkmagenta)</b></font> also forms complex with <scene name='MT1-MMP-TIMP-1_complex/Cv2/11'>wild-type TIMP-1</scene> ([[2j0t]], <font color='orange'><b>colored orange</b></font>), producing <scene name='MT1-MMP-TIMP-1_complex/Cv2/12'>similar hydrogen bond network in the WT TIMP-1 binding interface</scene> as well as <scene name='MT1-MMP-TIMP-1_complex/Cv2/13'>in the case with MT3-MMP</scene>. This network of hydrogen bonds stabilizes the CD and EF loops that compose the binding interface. Importantly, the <scene name='MT1-MMP-TIMP-1_complex/Cv2/14'>hydrogen bond between Cys1 and Ser68 may position the amino and carboxyl groups of Cys1 to effectively coordinate the Zn2+ ion</scene>. However, this MT1-MMP-WT-TIMP-1 complex is not tight-binding. MT1-MMP is unique since even though it exhibits high structural homology to all MMPs, it is not inhibited by TIMP-1, <scene name='MT1-MMP-TIMP-1_complex/Cv3/1'>but is inhibited by the structural homologous TIMP-2</scene> ([[1bqq]]). <scene name='MT1-MMP-TIMP-1_complex/Cv2/15'>The single point mutation T98L</scene> (mutant TIMP-1 is colored in <span style="color:yellow;background-color:black;font-weight:bold;">yellow</span> with <font color='red'><b>T98L shown in red</b></font>) transformed TIMP-1 into a high affinity inhibitor of MT1-MMP ([[3ma2]]). WT-TIMP-1, WT-TIMP-2, and TIMP-1 T98L mutant have kinetic dissociation binding constant (K_D) 1.53 x 10^-6, 5.61 x 10^-8, and 8.70 x 10^-8, respectively. So, K_D of WT-TIMP-2 is 2 orders of magnitude smaller than that of WT-TIMP-1, indicating the weak affinity between MT1-MMP and WT-TIMP-1. The TIMP-1 T98L mutant regained high-affinity binding to MT1-MMP, resulting in a 2 order of magnitude decrease in K_D, similar to the case for WT-TIMP-2, the ''in vivo'' inhibitor of MT1-MMP. The overall structures of the complexes of <font color='darkmagenta'><b>MT1-MMP</b></font>-<font color='orange'><b>WT-TIMP-1</b></font> and <font color='violet'><b>MT1-MMP</b></font>-<span style="color:yellow;background-color:black;font-weight:bold;">mutant-T98L-TIMP-1</span> are <scene name='MT1-MMP-TIMP-1_complex/Cv2/17'>relatively similar</scene>. Even the structure of <font color='magenta'><b>MT3-MMP</b></font>-<font color='orange'><b>WT-TIMP-1</b></font> is <scene name='MT1-MMP-TIMP-1_complex/Cv2/18'>similar to those of MT1-MMP-TIMP-1s</scene> (with <font color='orange'><b>wild-type</b></font> and <span style="color:yellow;background-color:black;font-weight:bold;">TIMP-1 T98L mutant</span>). <scene name='MT1-MMP-TIMP-1_complex/Cv4/1'>Leu98 is pointing toward MT1-MMP residues Pro259 and Phe260, establishing a strong hydrophobic core</scene>, which is situated near the MT1-MMP <scene name='MT1-MMP-TIMP-1_complex/Cv4/3'>catalytic Zn2+ ion surrounded by His239, His243, and His249</scene>. So, this T98L replacement may stabilize the entire area by establishing a strong hydrophobic core upon binding to the enzyme. However, it seems unlikely that these additional bonds could

account for the entire binding effect between MT1-MMP and TIMP-1. Statistical analysis of the <scene name='MT1-MMP-TIMP-1_complex/Cv2/15'>key hydrogen bond</scene> stabilities in the TIMP-1 T98L mutant reveals that the hydrogen bonds network in mutant form is significantly more stable than that in WT-TIMP-1. Mutations that enhance hydrogen

bond stability contribute to the stability of the bound-like, less flexible, conformation of TIMP-1, which eventually results in increasing binding affinity for MT1-MMP. Thus, mutation affected the instrinsic dynamics of the inhibitor rather than its structure, thereby facilitating the interaction.

 

 

<ref group="xtra">PMID:20545310</ref><references group="xtra"/>