Figure 4. Mutations that disrupted HypA/HypB interactions also abolished restoration of hydrogenase activity in vivo.

The ΔhypB strain was transformed with the empty vector control (pBAD), wild-type pBAD-EcHypB and its mutants (L78A, E79A or V80A). The hydrogenase activity of the cell lysate was compared to that of the parental strain. Expression of wild-type HypB recovered 73±21% hydrogenase activity. Noteworthy, for the mutations (L78A and V80A) that disrupted HypA/HypB interactions, the hydrogenase activity was significantly reduced, and was similar to that for the empty vector control. The p-values were obtained by Dunnett's Multiple Comparison Test to compare each setup with ΔhypB strain-WT.