Extended Data Fig. 6: (p)ppGpp and c-di-GMP inversely control SmbA activity to promote growth on glucose.
(a) Growth of Caulobacter wild type and different smbA mutants in M2G media. (b) Growth of Caulobacter wild type and mutants indicated in the rel + background diluted from stationary phase cultures (PYE) into fresh M2G containing 50 mM sodium chloride. The rcdG0::dgcZ strain harbours an IPTG-inducible (100 µM) copy of dgcZ on the chromosome. (c) Growth of Caulobacter wild type and Δrel mutant in M2X media supplemented with 50 mM sodium chloride. (d) Growth of Caulobacter Δrel mutants containing different smbA mutant alleles (as indicated) in M2G media supplemented with 30 mM sodium chloride. In panels (a-d), data represent the mean of n = 3 biological replicates ± SD. (e) SmbA specifically promotes growth on M2G. Caulobacter mutants smbA Q114A and smbA R143A harbouring plasmid pSA280 (Plac-dgcZ; 150 μM IPTG) were grown on minimal glucose (M2G), minimal xylose (M2X) and complex media (PYE) as indicated. Ratios of doubling times are indicated as a measure for the growth promoting role of SmbA under different conditions. Shown are the mean of n = 3 biological replicates ± SD. (f) Viability of Caulobacter Δrel mutants harbouring different smbA alleles was assayed by diluting cultures from stationary phase (PYE) onto solid MG2 agar plates. (g) Immunoblots of Caulobacter cell extracts (wild type and Δrel mutant) were stained using polyclonal anti-SmbA antisera. Cultures were grown as indicated in Fig. 1b and reached stationary at 15 hours. Similar results were obtained in three independent experiments.
