MmpS4 or MmpS5 is required for growth of <i>M. tuberculosis</i> under iron-limited conditions.

<p><b>A.</b> Expression of MmpS4 and MmpS5 in <i>Mtb</i>. Whole cell lysates from wt <i>Mtb</i> mc²6230, Δ<i>mmpS4</i>, Δ<i>mmpS5</i>, Δ<i>mmpS4/S5</i>, Δ<i>mmpS4/S5+mmpS4/S5</i>, Δ<i>mbtD</i>::<i>hyg</i>, and Δ<i>mmpS4/S5/mbtD</i>::<i>hyg</i> were probed by Western blot by using rabbit polyclonal antibodies raised against MmpS4 and MmpS5. The cytoplasmic fructose 1,6-bisphosphatase GlpX was used as a loading control and detected using an anti-GlpX antiserum. <b>B, C.</b> Serial dilutions of log-phase cultures of <i>Mtb</i> mc²6230, Δ<i>mmpS4</i>, Δ<i>mmpS5</i>, Δ<i>mmpS4/S5</i>, Δ<i>mmpS4/S5</i> fully complemented with <i>mmpS4</i> and <i>mmpS5</i>, Δ<i>mbtD</i>::<i>hyg</i>, and Δ<i>mmpS4/S5</i>Δ<i>mbtD</i>::<i>hyg</i> were spotted on low iron glycerol-alanine-salts (GAS) plates (<b>B</b>), or on low iron GAS plates with 5 µM hemoglobin as an iron source (<b>C</b>).