PknG senses amino acid availability to control metabolism and virulence of Mycobacterium tuberculosis
Fig 2
Disruption of pknG or removal of the phosphorylation motif of garA caused a nutrient-dependent growth defect in M. smegmatis.
(A) All strains grew at the same rate on standard Middlebrook 7H9 medium. (B) ΔgarAMs grew slower than wild type on minimal Sauton’s medium containing 20 mM propionate, 20 mM NH4Cl plus 0.05% tyloxapol, and this growth defect could be fully complemented by GarA lacking phosphorylation sites (truncated “trunc.” garA). (C + D) ΔpknGMs grew slower than wild type and formed clumps (inset photo) on medium containing glutamate as sole carbon (C) or nitrogen source (D) (minimal Sauton’s with either 30 mM glutamate plus tyloxapol, or 1% glycerol, 10 mM glutamate plus tyloxapol). Data plotted are the mean and standard deviation of at least 3 independent experiments. (E) ΔpknGMs formed clumps when glutamate was the sole carbon or nitrogen source. The photograph shows a microplate from growth curve (D) imaged at 60 hours. Growth of ΔgarAMs complemented with phosphoablative GarA (EAAS) was equivalent to that of ΔpknGMs complemented with truncated GarA in all tested conditions so only the dataset for truncated GarA is shown for clarity.