Fig. 4: Perturbing intracellular ppGpp predictably alters the surface-to-volume ratio.
From: Maintenance of cytoplasmic and membrane densities shapes cellular geometry in Escherichia coli
a The genetic system as adapted from Büke et al.46, allowing for inducible control over intracellular ppGpp concentrations (top). The expected effect of RelA or MeshI induction on ppGpp concentration, ribosomal proteome allocation, growth rate, and the surface-to-volume ratio (bottom). Observed effects of MeshI/RelA induction on b ribosomal allocation, c growth rate, and d surface-to-volume ratio in a glucose (diamonds) or casamino acid-supplemented glucose growth medium (squares). The predicted versus measured SA/V for MeshI (e gold markers) and RelA (f red markers) induction conditions. Gray circles correspond to the wildtype strain in different growth conditions. Thin and thick error bars correspond to the 95% (≈2σ) and 68% (≈1σ) credible regions of the posterior distribution for the surface-to-volume assuming a constant density ratio κ inferred in Fig. 3c. MeshI was induced with IPTG ( − : 0 μM  + : 100 μM,) and RelA was induced with doxycyline ( − : 0 ng/mL;  + : 2 ng/mL,  + + : 4 ng/mL).
