Flexibility and variability of TIMP binding: X-ray structure of the complex between collagenase-3/MMP-13 and TIMP-2

Area of Science:

• Biochemistry
• Structural Biology
• Molecular Medicine

Background:

• Matrix metalloproteinases (MMPs) are crucial enzymes involved in extracellular matrix remodeling.
• Dysregulated MMP activity, particularly MMP-13, is linked to pathological conditions like arthritis and cancer metastasis.
• Tissue inhibitors of metalloproteinases (TIMPs) counteract MMP activity, maintaining physiological balance.

Purpose of the Study:

• To elucidate the structural basis of MMP-13 inhibition by TIMP-2.
• To understand the molecular interactions governing the binding of TIMP-2 to the catalytic domain of MMP-13 (cdMMP-13).

Main Methods:

• X-ray crystallography was employed to determine the 2.0 Å crystal structure of the cdMMP-13/bovine TIMP-2 complex.
• Structural comparison with previously determined MMP/TIMP complexes was performed.

Main Results:

• The crystal structure reveals TIMP-2 binding within the active site cleft of MMP-13, similar to other MMP-TIMP complexes.
• A distinct relative orientation of TIMP-2 to MMP-13 was observed, differing by approximately 20 degrees compared to the MT1-MMP/TIMP-2 complex.
• TIMP-2 binding induces significant conformational changes in MMP-13, including movements of the catalytic zinc, active site loops, and S1' wall, leading to active site cleft constriction.

Conclusions:

• The N-terminal segment of TIMP-2 primarily dictates its positioning relative to the MMP active site.
• The flanking loops of TIMP-2 determine its specific orientation, adapting to individual target MMPs.
• This structural insight provides a foundation for designing targeted MMP inhibitors for therapeutic applications in diseases like arthritis and cancer.