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BP: Fachverband Biologische Physik
BP 4: DNA \& DNA Enzymes
BP 4.2: Talk
Monday, March 14, 2011, 14:30–14:45, ZEU 260
Partitioning of RNA polymerases in bacterial cells — •Stefan Klumpp1, Marco Mauri1, and Terence Hwa2 — 1Max Planck Institute of Colloids and Interfaces, Potsdam — 2University of California, San Diego
How frequently a gene is transcribed depends not only on its regulation, but also on the availability of the necessary molecular machinery, RNA polymerases (RNAPs) and their associated factors. The concentration of free RNAPs and factors, i.e. those that are available for the initiation of transcription, depends also on the demand by other genes, such that genes may compete for the transcription machinery. We used a model for the partitioning of RNAPs into several functional classes to address the effect of this competition [1]. The model has been tested against existing experimental data for the growth-rate dependence of constitutive transcription and the effects of RNAP overexpression. We find that the competition of genes for RNAPs generally plays a minor role, because a pool of RNAPs non-specifically bound to DNA buffers against such effects. For sigma factors, the component of the transcription machinery required for promoter recognition and binding, however, competition seems to play an important role and may actively be modulated by the cell during global switches in the gene expression program, such as in stress responses.
[1] S. Klumpp and T. Hwa, Proc Natl Acad Sci USA 105, 10245 (2008).