title: An extracellular matrix-localized metalloproteinase with an exceptional QEXXH metal binding site prefers copper for catalytic activity.
abstract: The extracellular matrix (ECM) of the simple multicellular organism Volvox contains many region-specific morphological elements and mediates a variety of developmental and physiological responses by modification of its components. The fact that >95% of the mature organism is ECM makes Volvox suitable as a model system for ECM investigations. VMPs are a family of Volvox genes that are homologous to zinc-dependent matrix metalloproteinases (MMPs). Here we describe the identification and purification of the first VMP protein, VMP3. The 470-kDa VMP3 glycoprotein is localized within the ECM, and its biosynthesis is induced by the sex pheromone. The metal binding motif of VMP3 is QEXXH, not HEXXH as known for approximately 1300 other metalloproteinases. VMP3 shows proteinase activity and is inhibited by EDTA or the MMP inhibitor GM 6001, but in contrast to all known proteinases, VMP3 clearly prefers copper for activity rather than zinc. The exchange from Q to H within the QEXXH motif abolishes its copper preference. The unique properties of VMP3 suggest a novel type of metalloproteinase.
authors.affiliation: Lehrstuhl Biochemie I, Universität Regensburg, D-93053 Regensburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Heitzer
authors.forename: Armin
authors.initials: A
authors.lastname: Hallmann
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000918:Antibody Specificity; D001483:Base Sequence; D001665:Binding Sites; D002384:Catalysis; D002413:Cations, Divalent / Q000494:pharmacology; D000460:Chlorophyta / Q000201:enzymology* / Q000502:physiology; D016384:Consensus Sequence; D003300:Copper / Q000494:pharmacology*; D017931:DNA Primers; D005109:Extracellular Matrix / Q000201:enzymology*; D007700:Kinetics; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D017354:Point Mutation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity; D015032:Zinc / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D017931:DNA Primers; D011994:Recombinant Proteins; D003300:Copper; D008666:Metalloendopeptidases; D015032:Zinc