Fig. 4: Redundancy in magnesium transport is strain-dependent.
From: A bacterial pan-genome makes gene essentiality strain-dependent and evolvable
a, SWISS-MODEL structures of core strain-dependent essential CorA (SP_0185) (Qmean = −2.27) and the second non-essential transporter SP_1751 (Qmean = -−2.82). Uniform red colour of the structure of SP_0185 indicates that the protein sequence of the transporter is fully conserved among S. pneumoniae strains. Non-essential transporter coded by SP_1751 conserved amino acids are represented in grey. Colours other than grey indicate residues with allelic variation across the PG collection. b, Genetic interactions with SP_0185 in strain PG04. Each dot represents a gene interacting with SP_0185, its type of interaction and functional category. Note that 5 out of 22 genes with a positive interaction code for magnesium-binding proteins, suggesting that preventing the use of Mg2+ for non-essential reactions can reduce the impact of ΔSP_0185. c, Growth of WT PG04 and ΔSP_0185 in SDMM with different MgCl2 concentrations and hexammine cobalt. Low Mg2+ significantly affects growth of ΔSP_0185 compared with WT PG04, while addition of hexammine cobalt abolishes growth of the knockout. Data shown are from n = 3 biologically independent samples, while independent repetition (3) showed similar results. Error bars represent s.d. d, Doubling time versus maximum OD observed for different strains growing in rich medium with MgCl2 at 0.15 mM and in the absence/presence of hexammine cobalt. Growth of WT strains in which SP_0185 is essential is similar to that of PG04-ΔSP_0185 (black dots). White and red dots represent WT strains where SP_0185 is non-essential or essential, respectively. Dots numbered 1 to 4 correspond to the numbered curves in c. e, Schematic showing the most common genomic configuration of SP_0185 and neighbouring uvrA, while some strains have a prophage in between. f, Transcript abundances of the two corA genes. Each dot represents a different WT strain, colours indicate SP_0185 essentiality and arrows indicate prophage presence. R and P values were derived from a least-squares linear regression.
