As mentioned above, it is well documented that Hyd-3 catalyzes hydrogen oxidation in vitro and can contribute ~ 90% of total hydrogen oxidation activity measured in crude extracts derived from fermentatively-grown cells [19, 20]. Figure 2 Staining comparison using hydrogen or formate as electron donor and different redox dye acceptors identifies Hyd-3 activity. Extracts from the strains MC4100, DHP-F2 (ΔhypF), FTD22 (ΔhyaB), FTD67 (ΔhybC), CP971 (ΔhycA-I), CP734 (ΔhyaB hybC), FTD147 (ΔhyaB hybB hycE), FTD150 (ΔhyaB hybC hycE hyfB-R), FM460 (ΔselC), GW-572016 mouse FM911 (ΔfdhF), CPD17 (ΔhyaB hybC fdhE), CPD23 (ΔhyaB hybC fdhE fdhF) and CPD24 (ΔhyaB hybC fdoG fdnG) that were

grown anaerobically in TGYEP media, pH 6.5 were used and 25 μg of protein were applied to non-denaturating PAGE (7.5% w/v polyacrylamide) and stained as indicated with either A: BV and TTC under a 100% hydrogen atmosphere, B: PMS and NBT under a 100% hydrogen atmosphere, or with C: BV, TTC and formate under 100% nitrogen atmosphere. In the interest

of clarity only the genotypes of the strains are given. On the right hand side of the figure the migration patterns of hydrogenase 1 (Hyd-1), Hyd-2 and the mixed species of Fdh-N and Fdh-O (Fdh-N/O) are indicated, as well as the presumed migration of active FHL (Hyd-3). The top of each gel is marked by an arrow. Fdh-H is required to stabilize Hyd-3 but is not essential for activity Because the FHL complex Selleck AR-13324 comprises not only Hyd-3 but also Fdh-H, it was necessary to determine whether the Fdh-H component was required for the visualization of the Hyd-3 activity. Analysis of extracts derived from strains devoid either of the respiratory formate dehydrogenases, Fdh-O

and Fdh-N, (CPD24 hyaB hybC fdoG fdnG), or the biosynthetic accessory protein FdhE involved in their assembly (CPD17 hyaB hybC fdhE) [25, 26], clearly showed that the Hyd-3 activity band had similar intensity to that in the wild-type (Figure 2A, right panel). 3-oxoacyl-(acyl-carrier-protein) reductase However, when the fdhF gene encoding Fdh-H was deleted either alone (FM911), or in combination with fdhE (CPD23), the intensity of the Hyd-3 activity band was significantly reduced (Figure 2A, right panel). A similar result was selleck observed when a crude extract derived from the selC mutant FM460, which cannot synthesize selenoproteins [27], was analysed. If membrane-associated, it would be expected that Fdh-H migrates together with Hyd-3 as part of a large FHL complex. In-gel formate-dependent BV reduction was therefore tested with the same samples of crude extracts. Following 16 h incubation with formate and BV/TTC under a N2 atmosphere two bands showing formate:BV oxidoreductase activity were observed, which migrated slightly more slowly that the Hyd-3 activity and with a much sharper banding pattern (Figure 2B).