FIGURE 2.

Heterologous HupSL enzyme activity is only detectable in fermentatively growing E. coli cells. (A) Crude extracts derived from FTD147 (ΔhyaBΔhybCΔhycE) transformed with plasmid phupXSL (1) or phupSL (2) after growth in M9 minimal medium with the indicated carbon sources were separated in native-PAGE and stained for hydrogenase enzyme activity, as described in the legend to Figure 1. (B) A western blot using peptide antibodies raised against HupL (Hartwig et al., 2017) is shown in which the same extracts used in part A were separated in 10% (w/v) SDS-PAGE. The molecular mass marker proteins are presented in kDa. MC4100 was the wild type strain.