title: Thioredoxin2 enhances the damaged DNA binding activity of mtTFA through direct interaction.
abstract: Mitochondrial transcription factor A (mtTFA) is a member of the HMG (high mobility group)-box protein family. We previously showed that mtTFA preferentially binds to both cisplatin-damaged and oxidatively damaged DNA. In this study, we found that expression levels of both mtTFA and the mitochondrial antioxidant protein thioredoxin2 (TRX2) are upregulated in cisplatin-resistant cell lines. In addition, TRX2 directly interacts with mtTFA and enhances its damaged DNA binding activity. The interaction between mtTFA and TRX2 requires the HMG box 1 motif of mtTFA. Furthermore, when amino acid substitutions were introduced at either C49G or C246stop, TRX2 interacted with mtTFA. However, the interaction of TRX2 with mtTFA was enhanced when both mutations (C49G and C246stop) were introduced. Binding to cisplatin-damaged DNA was similar among mutant mtTFA proteins. By contrast, binding to oxidized DNA was significantly enhanced when double mutations were introduced. These results suggest that TRX2 not only functions as an antioxidant, but also supports mtTFA functions.
authors.affiliation: Department of Molecular Biology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu 807-8555, Japan.
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kidani
authors.forename: Hiroto
authors.initials: H
authors.lastname: Izumi
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Eiji
authors.initials: E
authors.lastname: Kashiwagi
authors.forename: Haruki
authors.initials: H
authors.lastname: Ohmori
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Tanaka
authors.forename: Michihiko
authors.initials: M
authors.lastname: Kuwano
authors.forename: Kimitoshi
authors.initials: K
authors.lastname: Kohno
mesh_terms: D020816:Amino Acid Motifs; D000975:Antioxidants / Q000378:metabolism*; D015153:Blotting, Western; D004247:DNA / Q000378:metabolism*; D004249:DNA Damage / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D024101:Mitochondrial Proteins / Q000737:chemistry / Q000378:metabolism*; D013879:Thioredoxins / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; C467002:TXN2 protein, human; D014157:Transcription Factors; C422562:mitochondrial transcription factor A; D013879:Thioredoxins; D004247:DNA