uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Free RNA polymerase in Escherichia coli
Univ Wisconsin Madison, Dept Med Genet, Madison, WI USA..
Howard Hughes Med Inst, Ashburn, VA USA..
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology.
Univ Texas Dallas, Dept Mol & Cell Biol, Dallas, TX 75230 USA..
2015 (English)In: Biochimie, ISSN 0300-9084, E-ISSN 1638-6183, Vol. 119, 80-91 p.Article in journal (Refereed) PublishedText
Abstract [en]

The frequencies of transcription initiation of regulated and constitutive genes depend on the concentration of free RNA polymerase holoenzyme [R-f] near their promoters. Although RNA polymerase is largely confined to the nucleoid, it is difficult to determine absolute concentrations of [R-f] at particular locations within the nucleoid structure. However, relative concentrations of free RNA polymerase at different growth rates, [R-f](rel), can be estimated from the activities of constitutive promoters. Previous studies indicated that the rrnB P2 promoter is constitutive and that [R-f](rel) in the vicinity of rrnB P2 increases with increasing growth rate. Recently it has become possible to directly visualize Rf in growing Escherichia col cells. Here we examine some of the important issues relating to gene expression based on these new observations. We conclude that: (i) At a growth rate of 2 doublings/h, there are about 1000 free and 2350 non-specifically DNA-bound RNA polymerase molecules per average cell (12 and 28%, respectively, of 8400 total) which are in rapid equilibrium. (ii) The reversibility of the non-specific binding generates more than 1000 free RNA polymerase molecules every second in the immediate vicinity of the DNA. Of these, most rebind non-specifically to the DNA within a few ms; the frequency of non-specific binding is at least two orders of magnitude greater than specific binding and transcript initiation. (iii) At a given amount of RNA polymerase per cell, [R-f] and the density of non-specifically DNA-bound RNA polymerase molecules along the DNA both vary reciprocally with the amount of DNA in the cell. (iv) At 2 doublings/h an E. coli cell contains, on the average, about 1 non-specifically bound RNA polymerase per 9 kbp of DNA and 1 free RNA polymerase per 20 kbp of DNA. However some DNA regions (i.e. near active rRNA operons) may have significantly higher than average [R-f].

Place, publisher, year, edition, pages
2015. Vol. 119, 80-91 p.
Keyword [en]
Escherichia coli, Free RNA polymerase, Non-specifically bound RNA polymerase
National Category
Cell Biology
URN: urn:nbn:se:uu:diva-274453DOI: 10.1016/j.biochi.2015.10.015ISI: 000367022800010OAI: oai:DiVA.org:uu-274453DiVA: diva2:896468
Swedish Research Council, 2012-5042Knut and Alice Wallenberg Foundation, KAW 2009.0251
Available from: 2016-01-21 Created: 2016-01-21 Last updated: 2016-01-21Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Ehrenberg, Måns
By organisation
Department of Cell and Molecular Biology
In the same journal
Cell Biology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 144 hits
ReferencesLink to record
Permanent link

Direct link