Lrp, a major regulatory protein in Escherichia coli, bends DNA and can organize the assembly of a higher-order nucleoprotein structure.
Lrp (Leucine-responsive regulatory protein) is a global regulatory protein that controls the expression of many operons in Escherichia coli. One of those operons, ilvIH, contains six Lrp binding sites located within a several hundred base pair region upstream of the promoter region. Analysis of the binding of Lrp to a set of circularly permuted DNA fragments from this region indicates that Lrp induces DNA bending. The results of DNase I footprinting experiments suggest that Lrp binding to this region facilitates the formation of a higher-order nucleoprotein structure. To define more precisely the degree of bending associated with Lrp binding, one or two binding sites were separately cloned into a pBend vector and analyzed. Lrp induced a bend of approximately 52 degrees upon binding to a single binding site, and the angle of bending is increased to at least 135 degrees when Lrp binds to two adjacent sites. Lrp-induced DNA bending, and a natural sequence-directed bend that exists within ilvIH DNA, may be architectural elements that facilitate the assembly of a nucleoprotein complex.
Section of Genetics and Development, Cornell University, Ithaca, NY 14853.
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D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins; D051756:Leucine-Responsive Regulatory Protein; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009698:Nucleoproteins / Q000737:chemistry / Q000378:metabolism*; D009876:Operon; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C497278:Lrp protein, E coli; D009698:Nucleoproteins; D014157:Transcription Factors; D051756:Leucine-Responsive Regulatory Protein