title: Global orientation of bound MMP-3 and N-TIMP-1 in solution via residual dipolar couplings.
abstract: Crystal structures of catalytic domains of MMP-3 and MT1-MMP bound to TIMP-1 or TIMP-2, respectively, differ in the orientation of the TIMP in the MMP active site. The orientation in solution of N-TIMP-1 in the MMP-3 active site has been investigated using residual dipolar couplings (RDCs). Fitting of the RDCs to the X-ray structures of the complexes suggests general agreement with the orientation of crystalline MMP-3(DeltaC) and TIMP-1 and a large disparity from the orientation of crystalline MT1-MMP(DeltaC) and TIMP-2. Rigid body docking of MMP-3 and N-TIMP-1 X-ray coordinates using RDCs and intermolecular NOEs provided a time-averaged orientation in solution differing from the crystal structure by a 5 degrees rotation toward the MT1-MMP(DeltaC)/TIMP-2 orientation. The slight discrepancy in orientations in solution and crystal lies within the experimental uncertainties. Intermolecular NOEs used in the docking corroborated the accuracy of mapping the interface by a paramagnetic NMR footprinting assay, a potential alternative source of contacts for docking. Some uncertainty in the N-TIMP-1 orientation in the MMP-3 active site, coupled with microsecond to millisecond fluctuations of the MMP-binding ridge of N-TIMP-1 in the complex and flexibility in MMP-3(DeltaC) S(1)' to S(3)' subsites, leaves open the possibility that N-TIMP-1 might dynamically pivot a few degrees or more in the arc toward the MT1-MMP(DeltaC)/TIMP-2 orientation. Differing TIMP orientations in MMP active sites are more likely to result from structural differences in TIMP AB hairpin loops than from crystal packing artifacts.
authors.affiliation: Department of Biochemistry, 117 Schweitzer Hall, University of Missouri, Columbia, Missouri 65211, USA.
authors.forename: S
authors.initials: S
authors.lastname: Arumugam
authors.forename: Steven R
authors.initials: SR
authors.lastname: Van Doren
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry* / Q000378:metabolism; D002151:Calorimetry; D019277:Entropy; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D019278:Matrix Metalloproteinase 3 / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D013696:Temperature; D013816:Thermodynamics; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D019715:Tissue Inhibitor of Metalloproteinase-1; D019278:Matrix Metalloproteinase 3