title: 4-isoavenaciolide covalently binds and inhibits VHR, a dual-specificity phosphatase.
abstract: A potent inhibitor of a dual-specificity protein phosphatase, VHR (vaccinia H1 related), was isolated during a screening of microbial metabolites. This inhibitor was identified as 4-isoavenaciolide (4-iA), and was determined to irreversibly inhibit VHR phosphatase activity with a 50% inhibitory concentration of 1.2 microM. Detailed tandem mass spectrometry analyses of proteolysed fragments revealed that two molecules of 4-iA bound a molecule of VHR at the two different fragments: one containing the catalytic domain and the other containing the alpha6 helix positioned surface domain. As 4-iA possesses a reactive exo-methylene moiety, it is possible that 4-iA inhibits VHR through the direct binding to the cysteine residue in the catalytic site (Cys124). Furthermore, 4-iA inhibited dual-specificity protein phosphatases and tyrosine phosphatases, but did not inhibit serine/threonine phosphatases. These results suggest that 4-iA is a cysteine-targeting inhibitor of protein phosphatases with a common HCX5RS/T motif in the catalytic site.
authors.affiliation: Antibiotics Laboratory, RIKEN, Hirosawa 2-1, Wako-shi, 351-0198, Saitama, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Ueda
authors.forename: Takeo
authors.initials: T
authors.lastname: Usui
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakayama
authors.forename: Masashi
authors.initials: M
authors.lastname: Ueki
authors.forename: Koji
authors.initials: K
authors.lastname: Takio
authors.forename: Makoto
authors.initials: M
authors.lastname: Ubukata
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Osada
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000737:chemistry; D001665:Binding Sites / Q000502:physiology; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D002853:Chromatography, Liquid; D054640:Dual Specificity Phosphatase 3; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D005663:Furans / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology*; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D020539:Sequence Analysis, Protein; D013379:Substrate Specificity
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D004791:Enzyme Inhibitors; D005663:Furans; C465357:4-isoavenaciolide; D054640:Dual Specificity Phosphatase 3; D017027:Protein Tyrosine Phosphatases