Figure 2: Quantification of T7 RNAP noise and the intrinsic and extrinsic noises of downstream proteins.
From: Contribution of RNA polymerase concentration variation to protein expression noise
(a) Expression levels of CFP and mCherry by T7 RNAP at various aTc concentrations. (b) T7 RNAP noise obtained from the distribution of the YFP fluorescence intensity (Fig. 1c) as a function of the mean T7 RNAP concentration. The dotted line is fitted to the function a/R+b1,15, where R=the T7 RNAP concentration; a=38; and b=0.17. (c) The total (black open squares), extrinsic (red open circles) and intrinsic (green open triangles) noise of downstream protein expression, measured at each aTc concentration. Intrinsic noise is fitted to the function a/P+b, where P=mCherry fluorescence intensity; a=196; and b=−0.01 (dotted line). (d) The ratio of extrinsic noise to the RNAP noise, calculated at each aTc concentration. Error bars represent the mean±s.d. of three independent experiments.
