Extended Data Fig. 4: Growth rate dependence of constitutively expressed TetR and LacI.

(a) Two separated parts that constitutively expressed tetR and lacI with C-terminal sfgfp fusion were used for the measurement of their corresponding expression capacity. (b) Expression capacities \({{{\tilde{\mathbf \alpha }}}}_{{{\boldsymbol{R}}}}\) and \({{{\tilde{\mathbf \alpha }}}}_{{{\boldsymbol{G}}}}\) of constitutively expressed TetR and LacI, respectively, as a function of 1/λ. The dashed line indicates the steady-state expression capacity in the case of constant production of protein which is independent of growth rate (the constant value of protein production rate was the one of TetR in MOPS glucose medium). Both expression capacities increase faster than 1/λ as the growth rate decreases. (c) Relative protein expression capacity is defined as the ratio of TetR and LacI protein concentrations under different growth conditions. Results derived from data shown in Fig. 2a and Supplementary Table 7. (d) Relation between the mRNA abundance and growth rate during steady-state growth. (e) Relative mRNA level, defined as the ratio of mRNA abundance of tetR and lacI genes under different growth conditions (results derived from data shown in d). (f) Growth rate dependence of the normalized protein synthesis rates α_R and α_G. α_R and α_G are derived from experimental data of tetR and lacI expression, respectively, under different growth conditions, that is, \(\alpha _{{{{\boldsymbol{R}}}},{{{\boldsymbol{G}}}}} = \tilde \alpha _{{{{\boldsymbol{R}}}},{{{\boldsymbol{G}}}}} \cdot \lambda\). The synthesis rate obtained in different growth media was normalized to the value in MOPS glucose medium. Both synthesis rates have maxima around the moderate growth rates (~0.5 h⁻¹ for α_R and ~ 0.75 h⁻¹ for α_G). (g) Prediction of growth rate dependence of protein synthesis rate α obtained from measured mRNA abundance in panel d by considering the empirical growth rate dependence of translation activity (see details in Supplementary Note 3). Data in b, c and f are presented as mean ± SD defrom three or four independent biological replicates (n = 3-4, see Supplementary Table 7).

Source data