Molecular Evidence for a Fe-Hydrogenase in the Green Alga Scenedesmus obliquus

Wünschiers, Röbbe; Stangier, Kerstin A.; Senger, Horst; Schulz, Rüdiger

doi:10.1007/s002840010229

Cited by 38 publications

(22 citation statements)

References 22 publications

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“…Since then hydrogenases have been observed and characterized in many microorganisms, including some algae, trichomonads, anaerobic ciliates, and chytrid fungi (4,5,59,77,86,94,100,176,222,223,225). The enzyme catalyzes the simplest of chemical reactions, the reversible reductive formation of hydrogen from protons and electrons:…”

Section: Hydrogenasesmentioning

confidence: 99%

Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Tamagnini

Axelsson

Lindberg

et al. 2002

Microbiol Mol Biol Rev

466

372

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Cyanobacteria may possess several enzymes that are directly involved in dihydrogen metabolism: nitrogenase(s) catalyzing the production of hydrogen concomitantly with the reduction of dinitrogen to ammonia, an uptake hydrogenase (encoded by hupSL) catalyzing the consumption of hydrogen produced by the nitrogenase, and a bidirectional hydrogenase (encoded by hoxFUYH) which has the capacity to both take up and produce hydrogen. This review summarizes our knowledge about cyanobacterial hydrogenases, focusing on recent progress since the first molecular information was published in 1995. It presents the molecular knowledge about cyanobacterial hupSL and hoxFUYH, their corresponding gene products, and their accessory genes before finishing with an applied aspect—the use of cyanobacteria in a biological, renewable production of the future energy carrier molecular hydrogen. In addition to scientific publications, information from three cyanobacterial genomes, the unicellular Synechocystis strain PCC 6803 and the filamentous heterocystous Anabaena strain PCC 7120 and Nostoc punctiforme (PCC 73102/ATCC 29133) is included

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Section: Hydrogenasesmentioning

confidence: 99%

Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Tamagnini

Axelsson

Lindberg

et al. 2002

Microbiol Mol Biol Rev

466

372

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“…The monomeric form of the enzyme belongs to the class of [Fe]-hydrogenases (Voordouw et al 1989;Adams 1990;Meyer and Gagnon 1991;Happe et al 1994), or Fe-only hydrogenases (Peters et al 1998). Two homologous HydA nuclear genes (HydA1 and HydA2) have been cloned in green algae, which encode for such proteins (Florin et al 2001;Wünschiers et al 2001a;Forestier et al 2003). The proteins are imported in the chloroplast stroma (Happe et al 1994;Forestier et al 2003), where a functional [Fe]-hydrogenase is formed.…”

Section: Introductionmentioning

confidence: 99%

Photosynthetic H2 metabolism in Chlamydomonas reinhardtii (unicellular green algae)

Melis

2007

Planta

254

135

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Unicellular green algae have the ability to operate in two distinctly different environments (aerobic and anaerobic), and to photosynthetically generate molecular hydrogen (H2). A recently developed metabolic protocol in the green alga Chlamydomonas reinhardtii permitted separation of photosynthetic O2-evolution and carbon accumulation from anaerobic consumption of cellular metabolites and concomitant photosynthetic H2-evolution. The H2 evolution process was induced upon sulfate nutrient deprivation of the cells, which reversibly inhibits photosystem-II and O2-evolution in their chloroplast. In the absence of O2, and in order to generate ATP, green algae resorted to anaerobic photosynthetic metabolism, evolved H2 in the light and consumed endogenous substrate. This study summarizes recent advances on green algal hydrogen metabolism and discusses avenues of research for the further development of this method. Included is the mechanism of a substantial tenfold starch accumulation in the cells, observed promptly upon S-deprivation, and the regulated starch and protein catabolism during the subsequent H2-evolution. Also discussed is the function of a chloroplast envelope-localized sulfate permease, and the photosynthesis-respiration relationship in green algae as potential tools by which to stabilize and enhance H2 metabolism. In addition to potential practical applications of H2, approaches discussed in this work are beginning to address the biochemistry of anaerobic H2 photoproduction, its genes, proteins, regulation, and communication with other metabolic pathways in microalgae. Photosynthetic H2 production by green algae may hold the promise of generating a renewable fuel from nature's most plentiful resources, sunlight and water. The process potentially concerns global warming and the question of energy supply and demand.

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“…Many unicellular green algae code for an Fe-type 'hydrogenase' (Roessler and Lien 1984;Adams 1990; Happe and Naber 1993;Florin et al 2001;Wu¨nschiers et al 2001). This Fe-hydrogenase is coded for in the nucleus, synthesized in the cytosol and imported in the chloroplast stroma where it functions (Happe et al 1994).…”

Section: Introductionmentioning

confidence: 99%

Biochemical and morphological characterization of sulfur-deprived and H 2 -producing Chlamydomonas reinhardtii (green alga)

Zhang

Happe

Melis

2002

Planta

368

275

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Sulfur deprivation in green algae causes reversible inhibition of photosynthetic activity. In the absence of S, rates of photosynthetic O2 evolution drop below those of O2 consumption by respiration. As a consequence, sealed cultures of the green alga Chlamydomonas reinhardtii become anaerobic in the light, induce the "Fe-hydrogenase" pathway of electron transport and photosynthetically produce H2 gas. In the course of such H2-gas production cells consume substantial amounts of internal starch and protein. Such catabolic reactions may sustain, directly or in directly, the H2-production process. Profile analysis of selected photosynthetic proteins showed a precipitous decline in the amount of ribulose-1,5-bisphosphate carboxylase-oxygenase (Rubisco) as a function of time in S deprivation, a more gradual decline in the level of photosystem (PS) II and PSI proteins, and a change in the composition of the PSII light-harvesting complex (LHC-II). An increase in the level of the enzyme Fe-hydrogenase was noted during the initial stages of S deprivation (0-72 h) followed by a decline in the level of this enzyme during longer (t >72 h) S-deprivation times. Microscopic observations showed distinct morphological changes in C. reinhardtii during S deprivation and H2 production. Ellipsoid-shaped cells (normal photosynthesis) gave way to larger and spherical cell shapes in the initial stages of S deprivation and H2 production, followed by cell mass reductions after longer S-deprivation and H2-production times. It is suggested that, under S-deprivation conditions, electrons derived from a residual PSII H2O-oxidation activity feed into the hydrogenase pathway, thereby contributing to the H2-production process in Chlamydomonas reinhardtii. Interplay between oxygenic photosynthesis, mitochondrial respiration, catabolism of endogenous substrate, and electron transport via the hydrogenase pathway is essential for this light-mediated H2-production process.

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Molecular Evidence for a Fe-Hydrogenase in the Green Alga Scenedesmus obliquus

Cited by 38 publications

References 22 publications

Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Photosynthetic H2 metabolism in Chlamydomonas reinhardtii (unicellular green algae)

Biochemical and morphological characterization of sulfur-deprived and H 2 -producing Chlamydomonas reinhardtii (green alga)

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