title: Catalytic domain structures of MT-SP1/matriptase, a matrix-degrading transmembrane serine proteinase.
abstract: The type II transmembrane multidomain serine proteinase MT-SP1/matriptase is highly expressed in many human cancer-derived cell lines and has been implicated in extracellular matrix re-modeling, tumor growth, and metastasis. We have expressed the catalytic domain of MT-SP1 and solved the crystal structures of complexes with benzamidine at 1.3 A and bovine pancreatic trypsin inhibitor at 2.9 A. MT-SP1 exhibits a trypsin-like serine proteinase fold, featuring a unique nine-residue 60-insertion loop that influences interactions with protein substrates. The structure discloses a trypsin-like S1 pocket, a small hydrophobic S2 subsite, and an open negatively charged S4 cavity that favors the binding of basic P3/P4 residues. A complementary charge pattern on the surface opposite the active site cleft suggests a distinct docking of the preceding low density lipoprotein receptor class A domain. The benzamidine crystals possess a freely accessible active site and are hence well suited for soaking small molecules, facilitating the improvement of inhibitors. The crystal structure of the MT-SP1 complex with bovine pancreatic trypsin inhibitor serves as a model for hepatocyte growth factor activator inhibitor 1, the physiological inhibitor of MT-SP1, and suggests determinants for the substrate specificity.
authors.affiliation: Max-Planck-Institut für Biochemie, Abteilung Strukturforschung, Am Klopferspitz 18a, 82152 Martinsried, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Friedrich
authors.forename: Pablo
authors.initials: P
authors.lastname: Fuentes-Prior
authors.forename: Edgar
authors.initials: E
authors.lastname: Ong
authors.forename: Gary
authors.initials: G
authors.lastname: Coombs
authors.forename: Michael
authors.initials: M
authors.lastname: Hunter
authors.forename: Ryan
authors.initials: R
authors.lastname: Oehler
authors.forename: Diane
authors.initials: D
authors.lastname: Pierson
authors.forename: Richard
authors.initials: R
authors.lastname: Gonzalez
authors.forename: Robert
authors.initials: R
authors.lastname: Huber
authors.forename: Wolfram
authors.initials: W
authors.lastname: Bode
authors.forename: Edwin L
authors.initials: EL
authors.lastname: Madison
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D017931:DNA Primers; D005109:Extracellular Matrix / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D014357:Trypsin / Q000737:chemistry / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D012697:Serine Endopeptidases; C485595:matriptase; C485596:ST14 protein, human; D014357:Trypsin