The Transcriptional Regulatory Protein, YB-1, Promotes Single-stranded Regions in the DRA Promoter

• Published in: The Journal of biological chemistry Vol. 270; no. 8; pp. 3527 - 3533
• Main Authors: MacDonald, G H, Itoh-Lindstrom, Y, Ting, J P
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 24.02.1995
• Subjects: Base Sequence; Binding Sites; CCAAT-Enhancer-Binding Proteins; DNA Probes; DNA, Single-Stranded - metabolism; DNA-Binding Proteins - metabolism; HLA-DR alpha-Chains; HLA-DR Antigens - genetics; Humans; Molecular Sequence Data; NFI Transcription Factors; Nuclear Proteins; Promoter Regions, Genetic; Recombinant Proteins - metabolism; Transcription Factors; Tumor Cells, Cultured; Y-Box-Binding Protein 1
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.8.3527

YB-1 is a member of a newly defined family of DNA- and RNA-binding proteins, the Y box factors. These proteins have been shown to affect gene expression at both the transcriptional and translational levels. Recently, we showed that YB-1 represses interferon- -induced transcription of class II human major histocompatibility (MHC) genes( 1 ). Studies in this report characterize the DNA binding properties of purified, recombinant YB-1 on the MHC class II DRA promoter. The generation of YB-1-specific antibodies further permitted an analysis of the DNA binding properties of endogenous YB-1. YB-1 specifically binds single-stranded templates of the DRA promoter with greater affinity than double-stranded templates. The single-stranded DNA binding sites of YB-1 were mapped to the X box, whereas the double-stranded binding sites were mapped to the Y box of the DRA promoter, by methylation interference analysis. Most significantly, YB-1 can induce or stabilize single-stranded regions in the X and Y elements of the DRA promoter, as revealed by mung bean nuclease analysis. In concert with the findings that YB-1 represses DRA transcription, this study of YB-1 binding properties suggests a model of repression in which YB-1 binding results in single-stranded regions within the promoter, thus preventing loading and/or function of other DRA-specific transactivating factors.