The redox and DNA-repair activities of Ref-1 are encoded by nonoverlapping domains.
The DNA binding activity of transcription factor AP-1 is regulated in vitro by a posttranslational mechanism involving reduction/oxidation (redox). Redox regulation is mediated by a conserved cysteine residue in the DNA-binding domain of Fos and Jun. Previously, we demonstrated that a DNA repair protein, Ref-1, could stimulate the DNA binding activity of Fos-Jun dimers by reducing this cysteine residue. To examine the relationship between the redox and repair functions of Ref-1, we generated a series of deletion mutants. Analysis of the truncated proteins in vitro revealed that the redox and repair activities are encoded by distinct regions of Ref-1. Sequences in the N-terminal domain of Ref-1 that are not present in functionally related proteins from other organisms are required for the redox activity, whereas the DNA repair activity requires conserved C-terminal sequences. Chemical alkylation or oxidation of cysteine sulfhydryls inhibits the redox activity of Ref-1 without affecting its DNA repair activity. Crosslinking studies suggest that a direct cysteine-mediated interaction occurs between Ref-1 and Jun.
Xanthoudakis
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Roche Institute of Molecular Biology, Nutley, NJ 07110.
Miao
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Curran
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D019757:Carbon-Oxygen Lyases; D003545:Cysteine / Q000737:chemistry; D004252:DNA Mutational Analysis; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000737:chemistry; D006801:Humans; D046911:Macromolecular Substances; D009687:Nuclear Proteins / Q000737:chemistry*; D010084:Oxidation-Reduction; D011485:Protein Binding; D016755:Proto-Oncogene Proteins c-jun / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship
D046911:Macromolecular Substances; D009687:Nuclear Proteins; D016755:Proto-Oncogene Proteins c-jun; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); D019757:Carbon-Oxygen Lyases; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D003545:Cysteine