title: BJ46a, a snake venom metalloproteinase inhibitor. Isolation, characterization, cloning and insights into its mechanism of action.
abstract: Fractionation of the serum of the venomous snake Bothrops jararaca with (NH4)2SO4, followed by phenyl-Sepharose and C4-reversed phase chromatographies, resulted in the isolation of the anti-hemorrhagic factor BJ46a. BJ46a is a potent inhibitor of the SVMPs atrolysin C (class P-I) and jararhagin (P-III) proteolytic activities and B. jararaca venom hemorrhagic activity. The single-chain, acidic (pI 4.55) glycoprotein has a molecular mass of 46 101 atomic mass units determined by MALDI-TOF MS and 79 kDa by gel filtration and dynamic laser light scattering, suggesting a homodimeric structure. mRNA was isolated from the liver of one specimen and transcribed into cDNA. The cDNA pool was amplified by PCR, cloned into a specific vector and used to transform competent cells. Clones containing the complete coding sequence for BJ46a were isolated. The deduced protein sequence was in complete agreement with peptide sequences obtained by Edman degradation. BJ46a is a 322-amino-acid protein containing four putative N-glycosylation sites. It is homologous to the proteinase inhibitor HSF (member of the fetuin family, cystatin superfamily) isolated from the serum of the snake Trimeresurus flavoviridis, having 85% sequence identity. This is the first report of a complete cDNA sequence for an endogenous inhibitor of snake venom metalloproteinases (SVMPs). The sequence reveals that the only proteolytic processing required to obtain the mature protein is the cleavage of the signal peptide. Gel filtration analyses of the inhibitory complexes indicate that inhibition occurs by formation of a noncovalent complex between BJ46a and the proteinases at their metalloproteinase domains. Furthermore, the data shows that the stoichiometry involved in this interaction is of one inhibitor monomer to two enzyme molecules, suggesting an interesting mechanism of metalloproteinase inhibition.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Rio de Janeiro, Brazil.
authors.forename: R H
authors.initials: RH
authors.lastname: Valente
authors.forename: B
authors.initials: B
authors.lastname: Dragulev
authors.forename: J
authors.initials: J
authors.lastname: Perales
authors.forename: J W
authors.initials: JW
authors.lastname: Fox
authors.forename: G B
authors.initials: GB
authors.lastname: Domont
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017837:Bothrops / Q000097:blood; D003435:Crotalid Venoms / Q000494:pharmacology; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D007202:Indicators and Reagents / Q000494:pharmacology; D007460:Iodoacetamide / Q000031:analogs & derivatives / Q000494:pharmacology; D007525:Isoelectric Focusing; D008027:Light; D008099:Liver / Q000378:metabolism; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000494:pharmacology; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D012542:Scattering, Radiation; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D012910:Snake Venoms / Q000201:enzymology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013997:Time Factors; D014757:Viper Venoms / Q000737:chemistry* / Q000494:pharmacology*; D000097146:Bothrops jararaca Venom
chemical_list: D003435:Crotalid Venoms; D018076:DNA, Complementary; D010450:Endopeptidases; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D007460:Iodoacetamide; D008666:Metalloendopeptidases; D012333:RNA, Messenger; D012910:Snake Venoms; D014757:Viper Venoms; D000097146:Bothrops jararaca Venom; C431567:BJ46a anti-hemorrhagic factor; C080491:N-isopropyliodoacetamide; C039830:peptidyl-Lys metalloendopeptidase; C058921:endoproteinase Asp-N; C089232:atrolysin C