Effect of transcription factor resource sharing on gene expression noise
Fig 5
Introduction of competitor sites can lead to multi-modal mRNA distribution.
(A-B) The steady-state number distributions of mRNA molecules produced by two identical promoters are shown in absence of any competitor sites, with varying number of activators (A) and repressors (B). The kinetic rates are taken from Table 1. Insets: The mRNA distributions with a faster TF binding rate (kon = 0.027s-1) than the mRNA degradation rate (γ = 0.011s−1). Other parameters are as specified in Table 1. (C-D) The steady-state mRNA distributions for two identical promoters are shown in presence of competitor sites, when the TFs either act as activators (C) or repressors (D). For these plots, we choose a faster TF binding rate than mRNA degradation rate (as in the insets of A, B) such that the distributions are unimodal in absence of any competitor sites. The number of competitor sites is increased systematically keeping a fixed number of TFs (NTF = 3). For simplicity we assume that the TF binding and unbinding rates to the promoters are the same as to the competitor sites.