Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6491098 | Journal of Biotechnology | 2015 | 6 Pages |
Abstract
Proteorhodopsin (PR) is a light harvesting protein widely distributed among bacterioplankton that plays an integral energetic role in a new pathway of marine light capture. The conversion of light into chemical energy in non-chlorophyll-based bacterial systems could contribute to overcoming thermodynamic and metabolic constraints in biofuels production. In an attempt to improve biohydrogen production yields, H2 evolution catalyzed by endogenous hydrogenases, Hyd-3 and/or Hyd-4, was measured when recombinant proteorhodopsin (PR) was concomitantly expressed in Escherichia coli cells. Higher amounts of H2 were obtained with recombinant cells in a light and chromophore dependent manner. This effect was only observed when HyfR, the specific transcriptional activator of the hyf operon encoding Hyd-4 was overexpressed in E. coli, suggesting that an excess of protons generated by PR activity could increase hydrogen production by Hyd-4 but not by Hyd-3. Although many of the subunits of Hyd-3 and Hyd-4 are very similar, Hyd-4 possesses three additional proton-translocating NADH-ubiquinone oxidoreductase subunits, suggesting that it is dependent upon ÎμH+. Altogether, these results suggest that protons generated by proteorhodopsin in the periplasm can only enhance hydrogen production by hydrogenases with associated proton translocating subunits.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Bioengineering
Authors
TaÃs M. Kuniyoshi, Andrea Balan, Ana Clara G. Schenberg, Divinomar Severino, Patrick C. Hallenbeck,