Analysis of the CE-<i>hoxEFUYH</i> and CE-<i>hoxEFUYH</i>-<i>hypABCDEF</i> mutants for strong constitutive expression of the <i>hoxEFUYH</i> alone or together with the <i>hypABCDEF</i> genes.

<p>All experiments were performed at least three times on cells grown at 30°C under standard light. (<b>A</b>) Typical growth of the WT (squares), CE-<i>hoxEFUYH</i> (CE1; white triangles) and CE-<i>hoxEFUYH</i>-<i>hypABCDEF</i> (CE2; grey triangles) cells. (<b>B</b>) Histogram plot representation of the transcript abundance (measured by Real-time quantitative PCR) of the eight genes of the <i>hoxEFUYH</i> operon (left part) and the six <i>hypABCDEF</i> genes (right part) in the CE1 (grey bars) or CE2 (hatched bars) mutants, as compared to the WT strain (white bars). (<b>C</b>) Western blot analysis of the abundance of the HoxF and HoxH proteins in WT, CE1 or CE2 cells. (<b>D</b>) Histograms representation of the hydrogenase activities of WT (light grey), CE1 (dark grey) or CE2 cells (hatched bars) growing in standard medium (MM) or MM* (MM+17 µM Fe) supplemented with 2.5 µM NiSO₄.