Regulation of the transfer genes of Streptomyces plasmid pSN22: in vivo and in vitro study of the interaction of TraR with promoter regions.
Expression of the tra operon, essential for conjugative transfer of the 11-kb Streptomyces nigrifaciens plasmid pSN22, is negatively regulated by traR, which is located upstream of the tra operon and transcribed in the opposite orientation. The transcriptional start points for the tra and traR mRNAs were determined by primer extension; they are 72 bp apart and have identical -10 promoter sequences. The TraR protein was overexpressed in Escherichia coli and used for gel retardation and DNase I protection experiments. It bound specifically to the bidirectional tra-traR promoter region and protected four DNA regions, each of which contains a similar 12-bp sequence. The binding was strongest to the region downstream of the tra promoter, probably ensuring that expression of the potentially lethal traB gene is turned off before traR. The efficiency of intramycelial plasmid transfer was decreased by the mutation at the downstream region.
International Center of Cooperative Research in Biotechnology, Faculty of Engineering, Osaka University, Japan.
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Kataoka
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Kosono
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Seki
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Yoshida
D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins; D001483:Base Sequence; D001665:Binding Sites; D004269:DNA, Bacterial / Q000378:metabolism; D036781:Fimbriae Proteins; D015964:Gene Expression Regulation, Bacterial; D018014:Gene Transfer Techniques; D005798:Genes, Bacterial; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013302:Streptomyces / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C080512:TraR protein, Agrobacterium tumefaciens; D014157:Transcription Factors; D036781:Fimbriae Proteins