Heterologous expression of proteorhodopsin enhances H2 production in Escherichia coli when endogenous Hyd-4 is overexpressed.
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 ΔμH(+). Altogether, these results suggest that protons generated by proteorhodopsin in the periplasm can only enhance hydrogen production by hydrogenases with associated proton translocating subunits.
Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, 05508-900, São Paulo, Brazil. Electronic address: t.kuniyoshi@usp.br.
Taís M
TM
Kuniyoshi
Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, 05508-900, São Paulo, Brazil. Electronic address: abalan@usp.br.
Andrea
A
Balan
Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes, 1374, 05508-900, São Paulo, Brazil. Electronic address: acgschen@usp.br.
Ana Clara G
AC
Schenberg
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Professor Lineu Prestes, 748, 05508-000, São Paulo, Brazil. Electronic address: divinomar@gmail.com.
Divinomar
D
Severino
Département de Microbiologie, infectiologie et immunologie, Université de Montréal, CP 6168 Succursale Centre-ville, H2C 3J7, Montreal, Canada. Electronic address: patrick.hallenbeck@umontreal.ca.
Patrick C
PC
Hallenbeck
D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D006859:Hydrogen / Q000032:analysis / Q000378:metabolism*; D006864:Hydrogenase / Q000235:genetics / Q000378:metabolism*; D025604:Rhodopsins, Microbial / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D014801:Vitamin A
D029968:Escherichia coli Proteins; D025604:Rhodopsins, Microbial; C413548:proteorhodopsin; D014801:Vitamin A; D006859:Hydrogen; D006864:Hydrogenase; C455599:hydrogenase 4, E coli
Escherichia coli; Hydrogen production; Hydrogenase type IV; Proteorhodopsin