YB-1 promotes strand separation in vitro of duplex DNA containing either mispaired bases or cisplatin modifications, exhibits endonucleolytic activities and binds several DNA repair proteins.
YB-1 is a multifunctional protein involved in the regulation of transcription, translation, mRNA splicing and probably DNA repair. It contains a conserved cold shock domain and it binds strongly to inverted CCAAT box of different promoters. In this study, we have found that purified YB-1 oligomerizes readily in solutions to form trimers, hexamers and oligomers of 12 molecules. The presence of ATP changed the conformation of YB-1 in such a way that only dimers were detected by gel filtration analyses. Purified YB-1 can separate different DNA duplexes containing blunt ends, 5' or 3' recessed ends, or forked structures. This strand separation activity is increased on cisplatin-modified DNA or with duplex molecules containing mismatches. In addition to its exonuclease activity, YB-1 exhibits endonucleolytic activities in vitro. Finally, YB-1 affinity chromatography experiments have indicated that in addition to prespliceosome factors like nucleolin and ALY, YB-1 binds the DNA repair proteins MSH2, DNA polymerase delta, Ku80 and WRN proteins in vitro. Furthermore, immunofluorescence studies have shown that YB-1 re-localizes from the cytoplasm to nuclear areas containing either Ku80 or MSH2 proteins in human 293 embryonic kidney cells. These results suggest that YB-1 is involved in base excision and mismatch repair pathways.
Gaudreault
Isabelle
I
Centre de Recherche en Cancérologie de l'Université Laval, Hôpital Hôtel-Dieu de Québec, Centre Hospitalier Universitaire de Québec, 9 McMahon Street, Québec, G1R 2J6, Canada.
Guay
David
D
Lebel
Michel
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D034961:Antigens, Nuclear / Q000378:metabolism; D020137:Base Pair Mismatch; D020029:Base Pairing / Q000187:drug effects; D001483:Base Sequence; D002384:Catalysis; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002846:Chromatography, Affinity; D002945:Cisplatin / Q000378:metabolism* / Q000494:pharmacology; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004720:Endonucleases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D000072200:Ku Autoantigen; D051718:MutS Homolog 2 Protein; D009687:Nuclear Proteins; D009691:Nucleic Acid Denaturation / Q000187:drug effects; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D021381:Protein Transport; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D017384:Sequence Deletion; D013379:Substrate Specificity; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051840:Y-Box-Binding Protein 1
D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; D000255:Adenosine Triphosphate; D004247:DNA; D004720:Endonucleases; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen; D002945:Cisplatin