Acquisition of double-stranded DNA-binding ability in a hybrid protein between Escherichia coli CspA and the cold shock domain of human YB-1.
Escherichia coli CspA, a major cold shock protein, is dramatically induced upon temperature downshift. As it binds co-operatively to single-stranded DNA (ssDNA) and RNA without apparent sequence specificity, it has been proposed that CspA acts as an RNA chaperone to facilitate transcription and translation at low temperature. CspA consists of a five-stranded beta-barrel structure containing two RNA-binding motifs, RNP1 and RNP2. Eukaryotic Y-box proteins, such as human YB-1, are a family of nucleic acid-binding proteins that share a region of high homology with CspA (43% identity), termed the cold shock domain (CSD). Their cellular functions are very diverse and are associated with growth-related processes. Here, we replaced the six-residue loop region of CspA between the beta3 and beta4 strands with the corresponding region of the CSD of human YB-1 protein. The resulting hybrid protein became capable of binding to double-stranded DNA (dsDNA) in addition to ssDNA and RNA. The dsDNA-binding ability of an RNP1 point mutant (F20L) of the hybrid was almost unchanged. On the other hand, the dsDNA-binding ability of the hybrid protein was abolished in high salt concentrations in contrast to its ssDNA-binding ability. These results indicate that the loop region between the beta3 and beta4 strands of Y-box proteins, which is a little longer and more basic than that of CspA, plays an important role in their binding to dsDNA.
Wang
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N
Department of Biochemistry, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA.
Yamanaka
K
K
Inouye
M
M
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002942:Circular Dichroism; D003080:Cold Temperature; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D015342:DNA Probes; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D010957:Plasmids; D017433:Protein Structure, Secondary; D015347:RNA Probes; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012261:Ribonucleoproteins; D012269:Ribosomal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1
D001426:Bacterial Proteins; D022762:CCAAT-Enhancer-Binding Proteins; D002352:Carrier Proteins; D015342:DNA Probes; D004268:DNA-Binding Proteins; D051839:NFI Transcription Factors; D009687:Nuclear Proteins; D015347:RNA Probes; D016601:RNA-Binding Proteins; C082384:RNP1 protein, S cerevisiae; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D051840:Y-Box-Binding Protein 1; C070856:YBX1 protein, human; C062260:cold shock protein CS7.4, Bacteria; D004247:DNA