Dimerization of the testis brain RNA-binding protein (translin) is mediated through its C-terminus and is required for DNA- and RNA-binding.
Testis brain-RNA-binding protein (TB-RBP) is a single-stranded DNA- and RNA-binding protein that is involved in chromosomal translocations, mRNA transport and translational regulation. Here we show from in vitro and in vivo protein binding studies that TB-RBP dimers are the minimum structural unit needed for DNA- and RNA-binding. Truncation studies demonstrate that the C-terminus of 55 amino acids of TB-RBP is essential, but not sufficient for DNA- or RNA-binding, and deletion of the leucine zipper motif in the C-terminus abolishes DNA- and RNA-binding. Changing cysteine 225 in the C-terminus to alanine does not significantly reduce DNA- or RNA-binding, but reduces the stability of the dimer. We conclude that the leucine zipper motif is required to maintain two molecules of TB-RBP as a dimer which is stabilized by a disulfide bond involving cysteine 225.
Wu
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XQ
Center for Research on Reproduction and Women's Health and Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA.
Xu
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L
Hecht
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NB
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D003001:Cloning, Molecular; D003545:Cysteine; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004220:Disulfides; D016350:Leucine Zippers; D008297:Male; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016366:Open Reading Frames; D012313:RNA / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013737:Testis / Q000378:metabolism
D004268:DNA-Binding Proteins; D004220:Disulfides; D008869:Microtubule-Associated Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012313:RNA; D004247:DNA; D003545:Cysteine