Y box-binding protein-1 binds preferentially to single-stranded nucleic acids and exhibits 3'-->5' exonuclease activity.
We have previously shown that Y box-binding protein-1 (YB-1) binds preferentially to cisplatin-modified Y box sequences. Based on structural and biochemical data, we predicted that this protein binds single-stranded nucleic acids. In the present study we confirmed the prediction and also discovered some unexpected functional features of YB-1. We found that the cold shock domain of the protein is necessary but not sufficient for double-stranded DNA binding while the C-tail domain interacts with both single-stranded DNA and RNA independently of the cold shock domain. In an in vitro translation system the C-tail domain of the protein inhibited translation but the cold shock domain did not. Both in vitro pull-down and in vivo co-immunoprecipitation assays revealed that YB-1 can form a homodimer. Deletion analysis mapped the C-tail domain of the protein as the region of homodimerization. We also characterized an intrinsic 3'-->5' DNA exonuclease activity of the protein. The region between residues 51 and 205 of its 324-amino acid extent is required for full exonuclease activity. Our findings suggest that YB-1 functions in regulating DNA/RNA transactions and that these actions involve different domains.
Department of Molecular Biology, University of Occupational and Environmental Health, 1-1 Iseigaoka Yahatanisi-ku, Kitakyushu 807-8555, Japan.
H
H
Izumi
T
T
Imamura
G
G
Nagatani
T
T
Ise
T
T
Murakami
H
H
Uramoto
T
T
Torigoe
H
H
Ishiguchi
Y
Y
Yoshida
M
M
Nomoto
T
T
Okamoto
T
T
Uchiumi
M
M
Kuwano
K
K
Funa
K
K
Kohno
D001665:Binding Sites; D001667:Binding, Competitive; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002945:Cisplatin / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins; D019281:Dimerization; D005092:Exonucleases / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009154:Mutation; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D009841:Oligonucleotides / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D014176:Protein Biosynthesis; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors; D014407:Tumor Cells, Cultured; D051840:Y-Box-Binding Protein 1
D022762:CCAAT-Enhancer-Binding Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D009841:Oligonucleotides; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; D004247:DNA; D005982:Glutathione Transferase; D005092:Exonucleases; D002945:Cisplatin