Curvature of Dinucleotide Poised for Formation of Trinucleotide in Transcription with Escherichia coli RNA Polymerase

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• 作者：Carl S. Garland ; Edward Tarien ; Ramadas Nirmala ; Patricia Clark ; Joseph Rifkind ; and Gunther L. Eichhorn
• 刊名：Biochemistry
• 出版年：1999
• 出版时间：March 16, 1999
• 年：1999
• 卷：38
• 期：11
• 页码：3421 - 3425
• 全文大小：53K
• 年卷期：v.38,no.11(March 16, 1999)
• ISSN：1520-4995

文摘

A frequently used schematic model of transcriptional elongation shows an RNA polymerasemolecule moving along a linear DNA. This model is of course highly idealized and not compatible withpromoter sequences [Gralla, J. D. (1991) Cell 66, 415-418; Schleif, R. (1992) Annu. Rev. Biochem. 61,199-223] and regulatory proteins [Koleske, A. J., and Young, R. A. (1995) Trends Biochem. Sci. 20,113-116; Dunaway, M., and Dröge, P. (1989) Nature 341, 657-659; Müller, H. P., Sogo, J. M., andSchaffner, W. (1989) Cell 58, 767-777] located some distance away from the point of transcriptioninitiation [Karsten, R., von Hippel, P. H., and Langowski, J. (1995) Trends Biochem. Sci. 20, 500-506].These circumstances lead to the expectation of curvature along the DNA strand and require looping betweensometimes distant points. We have now shown curvature in a dinucleotide formed at the very onset oftranscription when it is poised for reaction with a mononucleotide to form a trinucleotide. The curvaturebecame evident from the demonstration that a metal ion bound with a mononucleotide in the i+1(elongation) site is approximately equidistant from bases at the 5' end (i-1 site) and 3' end (i site) of thedinucleotide. Similar results were obtained with three different dinucleotides and four mononucleotides.Curvature of the RNA initiate may reflect curvature of the DNA to which it is bound. These studies showcurvature to be a significant feature in the interaction between DNA template and RNA elongate even atthe very beginning of transcription.