T6SS-4 is essential for <i>Yptb</i> survival under oxidative stress.

<p><b>A-C</b>. Indicated bacterial strains grown to mid-exponential phase were exposed to H₂O₂ for 1 hour and the viability of the cells was determined. Note that the <i>clpV4M</i> mutant defective in ATPase activity failed to complement the <i>clpV4</i> mutant. <b>D</b>. Oxidative stress induced the expression of T6SS-4. Cells of relevant <i>Yptb</i> strains harboring <i>P</i>_T6SS-4::<i>lacZ</i> or <i>P</i>_<i>katG</i>::<i>lacZ</i> were treated with indicated amounts of H₂O₂ and the expression of the reporter was measured. Data shown were the average of three independent experiments; error bars indicate SD from three independent experiments. ***, <i>p</i><0.001; **, <i>p</i><0.01.