Two open complexes and a requirement for Mg2+ to open the lambda PR transcription start site.
Potassium permanganate (KMnO4) footprinting in the absence and presence of magnesium (Mg2+) at the lambda PR promoter identified two different open complexes with Escherichia coli E sigma 70 RNA polymerase (designated RPo1 and RPo2). The single-stranded region in RPo1 (formed in the absence of Mg2+) was at most 12 bases long, whereas that in RPo2 (formed in the presence of Mg2+) spanned at least 14 bases. Only in RPo2 did the single-stranded region extend to the start point of transcription (+1, +2). These results provide a structural basis for the requirement for uptake of Mg2+ in the formation of RPo2 from RPo1, as deduced from kinetic studies at this promoter.
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Department of Chemistry, University of Wisconsin, Madison 53706.
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D001464:Barium / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D004277:DNA, Single-Stranded / Q000737:chemistry* / Q000378:metabolism; D004278:DNA, Superhelical / Q000737:chemistry / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D008274:Magnesium / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010957:Plasmids; D011196:Potassium Permanganate / Q000378:metabolism / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011743:Pyrimidines / Q000378:metabolism; D013696:Temperature; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D004277:DNA, Single-Stranded; D004278:DNA, Superhelical; D011743:Pyrimidines; D011196:Potassium Permanganate; D001464:Barium; D012321:DNA-Directed RNA Polymerases; D008274:Magnesium; D002118:Calcium