title: Nitric oxide-mediated inhibition of Hdm2-p53 binding.
abstract: It has become increasingly evident that nitric oxide exerts its effects, in part, by S-nitrosylation of cysteine residues. We tested in vitro whether nitric oxide may indirectly control p53 by S-nitrosylation and inactivation of the p53 negative regulator, Hdm2. Treatment of Hdm2 with a nitric oxide donor inhibits Hdm2-p53 binding, a critical step in Hdm2 regulation of p53. The presence of excess amounts of cysteine or dithiothreitol blocks this inhibition of binding. Moreover, nitric oxide inhibition of Hdm2-p53 binding was found to be reversible. Sulfhydryl sensitivity and reversibility are consistent with nitrosylation. Finally, we have identified a critical cysteine residue that nitric oxide modifies to disrupt Hdm2-p53 binding. This cysteine is proximal to the Hdm2-p53 binding interface and is conserved across species from zebrafish to humans. Mutation of this residue from a cysteine to an alanine does not interfere with binding but rather eliminates the sensitivity of Hdm2 to nitric oxide inactivation.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, Massachusetts 01605, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Schonhoff
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Daou
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Jones
authors.forename: Celia A
authors.initials: CA
authors.lastname: Schiffer
authors.forename: Alonzo H
authors.initials: AH
authors.lastname: Ross
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003545:Cysteine / Q000737:chemistry; D004229:Dithiothreitol / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D005978:Glutathione / Q000737:chemistry / Q000378:metabolism; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins; D011485:Protein Binding / Q000187:drug effects*; D011487:Protein Conformation; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014226:Triazenes / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C105351:1-hydroxy-2-oxo-3,3-bis(2-aminoethyl)-1-triazene; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D014226:Triazenes; D016159:Tumor Suppressor Protein p53; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D005982:Glutathione Transferase; D005978:Glutathione; D003545:Cysteine; D004229:Dithiothreitol