Figure 4

Magnesium inhibits the access of PG hydrolases to their substrate. (a, b) Autolysis curves of live cells (a) and of isolated sacculi (b) of the wild-type and the ΔmreB mutant grown to mid-exponential phase in LB medium containing 25 mM Mg²⁺ and autolysed in unsupplemented PBS (dashed lines) or in PBS containing 25 mM Mg²⁺ (plain lines). Autolysis rate is expressed as percentage of the maximum initial OD_600nm. (c, d) Growth curve of the wild-type (c) and the ΔmreB mutant (d) strains in LB medium supplemented (plain lines) or not (dashed lines) with 25 mM Mg²⁺ in the presence or not of 100 µg/ml purified recombinant LytE.