Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Tamagnini, Paula; Axelsson, Rikard; Lindberg, Pia; Oxelfelt, Fredrik; Wünschiers, Röbbe; Lindblad, Peter

doi:10.1128/mmbr.66.1.1-20.2002

Cited by 466 publications

(384 citation statements)

References 221 publications

(292 reference statements)

Supporting

Mentioning

373

Contrasting

Unclassified

Order By: Relevance

“…In C. watsonii, the expression of hup genes for uptake hydrogenase and hypAB and hypD genes for hydrogenase maturation proteins (Tamagnini et al, 2002) resembled the expression of the nif genes (Figure 3a), but the maximum hup and hyp transcript abundance was 5 h earlier than maximum transcript abundance of nif genes. This pattern is similar to the one observed for hup genes in other cyanobacteria (Leitão et al, 2005).…”

Section: Crocosphaera Diel Gene Expression T Shi Et Almentioning

confidence: 99%

Genome-wide analysis of diel gene expression in the unicellular N2-fixing cyanobacterium Crocosphaera watsonii WH 8501

et al. 2010

View full text Add to dashboard Cite

The unicellular cyanobacterium Crocosphaera watsonii is an important nitrogen fixer in oligotrophic tropical and subtropical oceans. Metabolic, energy and cellular processes in cyanobacteria are regulated by the circadian mechanism, and/or follow the rhythmicity of light-dark cycles. The temporal separation of metabolic processes is especially essential for nitrogen fixation because of inactivation of the nitrogenase by oxygen. Using a microarray approach, we analyzed gene expression in cultures of Crocosphaera watsonii WH 8501 (C. watsonii) over a 24-h period and compared the whole-genome transcription with that in Cyanothece sp. ATCC 51142 (Cyanothece), a unicellular diazotroph that inhabits coastal marine waters. Similar to Cyanothece, regulation at the transcriptional level in C. watsonii was observed for all major metabolic and energy processes including photosynthesis, carbohydrate and amino acid metabolisms, respiration, and nitrogen fixation. Increased transcript abundance for iron acquisition genes by the end of the day appeared to be a general pattern in the unicellular diazotrophs. In contrast, genes for some ABC transporters (for example, phosphorus acquisition), DNA replication, and some genes encoding hypothetical proteins were differentially expressed in C. watsonii only. Overall, C. watsonii showed a higher percentage of genes with light-dark cycling patterns than Cyanothece, which may reflect the habitats preferences of the two cyanobacteria. This study represents the first whole-genome expression profiling in cultivated Crocosphaera, and the results will be useful in determining the basal physiology and ecology of the endemic Crocosphaera populations.

show abstract

Section: Crocosphaera Diel Gene Expression T Shi Et Almentioning

confidence: 99%

Genome-wide analysis of diel gene expression in the unicellular N2-fixing cyanobacterium Crocosphaera watsonii WH 8501

et al. 2010

View full text Add to dashboard Cite

show abstract

“…The [NiFe] hydrogenases are found in a variety of anaerobic and facultative archaea, eubacteria, and cyanobacteria, and they typically consist of two distinct peptides that are referred to as the large and small subunits (2,12). Structural data obtained from x-ray crystallographic studies show a catalytic site containing a Ni-Fe binuclear center buried inside the large subunit (13,14).…”

mentioning

confidence: 99%

Discovery of Two Novel Radical S-Adenosylmethionine Proteins Required for the Assembly of an Active [Fe] Hydrogenase

Posewitz

King

Smolinski

et al. 2004

Journal of Biological Chemistry

378

385

View full text Add to dashboard Cite

To identify genes necessary for the photoproduction of H 2 in Chlamydomonas reinhardtii, random insertional mutants were screened for clones unable to produce H 2 . One of the identified mutants, denoted hydEF-1, is incapable of assembling an active [Fe] hydrogenase. Although the hydEF-1 mutant transcribes both hydrogenase genes and accumulates full-length hydrogenase protein, H 2 production activity is not observed. The HydEF protein contains two unique domains that are homologous to two distinct prokaryotic proteins, HydE and HydF, which are found exclusively in organisms containing [Fe] hydrogenase. In the C. reinhardtii genome, the HydEF gene is adjacent to another hydrogenase-related gene, HydG. Hydrogen has enormous potential to serve as a non-polluting fuel, alleviating the environmental and political concerns associated with fossil energy utilization. Among the most efficient H 2 -generating catalysts known are the [Fe] hydrogenase enzymes, which are found in numerous microorganisms, including the photosynthetic green alga Chlamydomonas reinhardtii (1, 2). Our research, aimed at identifying accessory proteins required for H 2 production in C. reinhardtii, has resulted in the discovery of two [Fe] hydrogenase assembly genes. These genes are essential for the formation of an active [Fe] hydrogenase and are conserved among sequenced organisms containing [Fe] hydrogenase enzymes.Algal H 2 production was first reported by Hans Gaffron and co-workers in seminal experiments performed over 60 years ago (3). Photosynthetic green algae are unique in that H 2 production by [Fe] hydrogenases is coupled directly to water oxidation through photosystem II and the photosynthetic electron transport chain, providing the means to generate H 2 using sunlight. In the past 5 years, great strides have been made in sustaining H 2 photoproduction activity in C. reinhardtii (4, 5), and intensive research continues to probe novel ways to use this and other photosynthetic organisms to generate renewable H 2 .Hydrogenases containing metallo-catalytic clusters occur as [NiFe] or [Fe]-only enzymes (2, 6, 7). These two forms are phylogenetically distinct (8), which suggests that hydrogenase function is the result of convergent evolution (2). Although [NiFe] and [Fe] hydrogenases are genetically unrelated, similarities between the proteins do exist. First, the active sites of both enzymes contain CO and CN ligands, and, second, each active site contains a binuclear metal center. In general, [NiFe] hydrogenases catalyze H 2 uptake, whereas [Fe] hydrogenases tend to catalyze H 2 evolution (9). Furthermore, the turnover number of [Fe] hydrogenases is 10 -100 times higher than that of [NiFe] hydrogenases (9), making the former one of the most efficient H 2 production catalysts known. Hydrogenases containing NiFeSe (10) and a unique class of hydrogenases containing a single Fe atom bound to a co-factor have also been reported (11).The [NiFe] hydrogenases are found in a variety of anaerobic and facultative archaea, eubacteria, a...

show abstract

“…This process can be driven by hydrogenase enzymes, capable of catalyzing the reversible reaction 2H þ þ 2e − → H 2 (2). Native cyanobacterial hydrogenases are predominantly thought to function in the recapture of hydrogen that is created as a byproduct of nitrogenase activity within nitrogen-fixing microbes (3). Hydrogenases may further function to provide a terminal electron sink in the absence of oxygen or during changes in flux through the photosynthetic machinery (4,5).…”

mentioning

confidence: 99%

Rewiring hydrogenase-dependent redox circuits in cyanobacteria

Ducat

Sachdeva

Silver

2011

Proc. Natl. Acad. Sci. U.S.A.

115

View full text Add to dashboard Cite

Hydrogenases catalyze the reversible reaction 2H þ þ 2e − ↔ H 2 with an equilibrium constant that is dependent on the reducing potential of electrons carried by their redox partner. To examine the possibility of increasing the photobiological production of hydrogen within cyanobacterial cultures, we expressed the [FeFe] hydrogenase, HydA, from Clostridium acetobutylicum in the nonnitrogen-fixing cyanobacterium Synechococcus elongatus sp. 7942. We demonstrate that the heterologously expressed hydrogenase is functional in vitro and in vivo, and that the in vivo hydrogenase activity is connected to the light-dependent reactions of the electron transport chain. Under anoxic conditions, HydA activity is capable of supporting light-dependent hydrogen evolution at a rate >500-fold greater than that supported by the endogenous [NiFe] hydrogenase. Furthermore, HydA can support limited growth solely using H 2 and light as the source of reducing equivalents under conditions where Photosystem II is inactivated. Finally, we demonstrate that the addition of exogenous ferredoxins can modulate redox flux in the hydrogenase-expressing strain, allowing for greater hydrogen yields and for dark fermentation of internal energy stores into hydrogen gas.biofuel | metabolic engineering

show abstract

Hydrogenases and Hydrogen Metabolism of Cyanobacteria

Cited by 466 publications

References 221 publications

Genome-wide analysis of diel gene expression in the unicellular N2-fixing cyanobacterium Crocosphaera watsonii WH 8501

Genome-wide analysis of diel gene expression in the unicellular N2-fixing cyanobacterium Crocosphaera watsonii WH 8501

Discovery of Two Novel Radical S-Adenosylmethionine Proteins Required for the Assembly of an Active [Fe] Hydrogenase

Rewiring hydrogenase-dependent redox circuits in cyanobacteria

Contact Info

Product

Resources

About