title: Structure of a novel leech carboxypeptidase inhibitor determined free in solution and in complex with human carboxypeptidase A2.
abstract: Leech carboxypeptidase inhibitor (LCI) is a novel protein inhibitor present in the medicinal leech Hirudo medicinalis. The structures of LCI free and bound to carboxypeptidase A2 (CPA2)have been determined by NMR and X-ray crystallography, respectively. The LCI structure defines a new protein motif that comprises a five-stranded antiparallel beta-sheet and one short alpha-helix. This structure is preserved in the complex with human CPA2 in the X-ray structure, where the contact regions between the inhibitor and the protease are defined. The C-terminal tail of LCI becomes rigid upon binding the protease as shown in the NMR relaxation studies, and it interacts with the carboxypeptidase in a substrate-like manner. The homology between the C-terminal tails of LCI and the potato carboxypeptidase inhibitor represents a striking example of convergent evolution dictated by the target protease. These new structures are of biotechnological interest since they could elucidate the control mechanism of metallo-carboxypeptidases and could be used as lead compounds for the search of fibrinolytic drugs.
authors.affiliation: Department de Bioquímica i Biologia Molecular, Unitat de Ciències and Institut de Biologia Fonamental, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Reverter
authors.forename: C
authors.initials: C
authors.lastname: Fernández-Catalán
authors.forename: R
authors.initials: R
authors.lastname: Baumgartner
authors.forename: R
authors.initials: R
authors.lastname: Pfänder
authors.forename: R
authors.initials: R
authors.lastname: Huber
authors.forename: W
authors.initials: W
authors.lastname: Bode
authors.forename: J
authors.initials: J
authors.lastname: Vendrell
authors.forename: T A
authors.initials: TA
authors.lastname: Holak
authors.forename: F X
authors.initials: FX
authors.lastname: Avilés
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001709:Biotechnology; D002268:Carboxypeptidases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism*; D002384:Catalysis; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D015195:Drug Design; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism; D019143:Evolution, Molecular; D006801:Humans; D007865:Leeches / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D018583:Pliability; D011480:Protease Inhibitors; D011485:Protein Binding; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D012996:Solutions; D013329:Structure-Activity Relationship
chemical_list: D004220:Disulfides; D004792:Enzyme Precursors; C116332:LCI protein, Hirudo medicinalis; D010940:Plant Proteins; D011480:Protease Inhibitors; D011506:Proteins; D012996:Solutions; D002268:Carboxypeptidases