Mg2+ mediated sequence-specific binding of transcriptional activator protein C of bacteriophage Mu to DNA.
The contributions from the secondary structure of the transcriptional activator protein C of bacteriophage Mu to its specific DNA binding and the influence of various factors, viz., electrolytes, and minor groove and major groove binders on this protein-DNA interaction have been addressed. Circular dichroism (CD) spectral results suggest that, in the absence of Mg2+, C protein exhibits a beta-pleated sheetlike structure and Mg2+ changes the conformation to a more alpha-helical structure which could provide specific geometrical constraints complementary to those of DNA-helix. Thus, Mg2+ acts as a cofactor for the binding of the C protein to its specific site in DNA by inducing conformational changes in the protein. Competitive binding studies with minor and major groove binding drugs, viz., distamycin A and methyl green, respectively, and the DMS footprinting data indicate that the C protein recognizes the major groove of DNA during complex formation. Further, upon major groove binding, C protein brings about changes in DNA conformation; such conformational changes could have implications in the transcription process.
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Microbiology and Cell Biology Department, Indian Institute of Science, Bangalore.
Ramesh
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Mahadevan
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Nagaraja
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D000595:Amino Acid Sequence; D010583:Bacteriophage mu / Q000235:genetics* / Q000378:metabolism*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001667:Binding, Competitive / Q000235:genetics; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism*; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D008274:Magnesium / Q000378:metabolism* / Q000494:pharmacology; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D013050:Spectrometry, Fluorescence; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*; D014764:Viral Proteins
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C090591:C protein, Bacteriophage Mu; D004268:DNA-Binding Proteins; D015534:Trans-Activators; D014764:Viral Proteins; D004247:DNA; D008274:Magnesium