title: Molecular basis for the redox control of nuclear transport of the structural chromatin protein Hmgb1.
abstract: Oxidative stress can induce a covalent disulfide bond between protein and peptide thiols that is reversible through enzymatic catalysis. This process provides a post-translational mechanism for control of protein function and may also protect thiol groups from irreversible oxidation. High mobility group protein B1 (Hmgb1), a DNA-binding structural chromosomal protein and transcriptional co-activator was identified as a substrate of glutaredoxin. Hmgb1 contains 3 cysteines, Cys23, 45, and 106. In mild oxidative conditions, Cys23 and Cys45 readily form an intramolecular disulfide bridge, whereas Cys106 remains in the reduced form. The disulfide bond between Cys23 and Cys45 is a target of glutathione-dependent reduction by glutaredoxin. Endogenous Hmgb1 as well as GFP-tagged wild-type Hmgb1 co-localize in the nucleus of CHO cells. While replacement of Hmgb1 Cys23 and/or 45 with serines did not affect the nuclear distribution of the mutant proteins, Cys106-to-Ser and triple cysteine mutations impaired nuclear localization of Hmgb1. Our cysteine targeted mutational analysis suggests that Cys23 and 45 induce conformational changes in response to oxidative stress, whereas Cys106 appears to be critical for the nucleocytoplasmic shuttling of Hmgb1.
authors.affiliation: Cole Eye Institute, Cleveland Clinic, Cleveland, OH 44195, USA. hoppeg@ccf.org
authors.forename: George
authors.initials: G
authors.lastname: Hoppe
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Talcott
authors.forename: Sanjoy K
authors.initials: SK
authors.lastname: Bhattacharya
authors.forename: John W
authors.initials: JW
authors.lastname: Crabb
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Sears
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006224:Cricetinae; D003545:Cysteine / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D054477:Glutaredoxins; D024243:HMGB1 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000378:metabolism; D011490:Protein Disulfide Reductase (Glutathione) / Q000378:metabolism; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D004220:Disulfides; D054477:Glutaredoxins; D024243:HMGB1 Protein; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); D003545:Cysteine