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Kumar S, Sharma S, Thakur S, Mishra T, Negi P, Mishra S, Hesham AEL, Rastegari AA, Yadav N, Yadav AN. Bioprospecting of Microbes for Biohydrogen Production: Current Status and Future Challenges. BIOPROCESSING FOR BIOMOLECULES PRODUCTION 2019:443-471. [DOI: 10.1002/9781119434436.ch22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Affiliation(s)
| | | | | | | | | | | | - Abd El-Latif Hesham
- Genetics Department, Faculty of Agriculture; Assiut University; Assiut Egypt
| | - Ali A. Rastegari
- Department of Molecular and Cell Biochemistry, Falavarjan Branch; Islamic Azad University; Isfahan Iran
| | - Neelam Yadav
- Gopi Nath P.G. College; Veer Bahadur Singh Purvanchal University; India
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Ghirardi ML. Implementation of photobiological H2 production: the O 2 sensitivity of hydrogenases. PHOTOSYNTHESIS RESEARCH 2015; 125:383-93. [PMID: 26022106 DOI: 10.1007/s11120-015-0158-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/13/2015] [Indexed: 05/10/2023]
Abstract
The search for the ultimate carbon-free fuel has intensified in recent years, with a major focus on photoproduction of H2. Biological sources of H2 include oxygenic photosynthetic green algae and cyanobacteria, both of which contain hydrogenase enzymes. Although algal and cyanobacterial hydrogenases perform the same enzymatic reaction through metallo-clusters, their hydrogenases have evolved separately, are expressed differently (transcription of algal hydrogenases is anaerobically induced, while bacterial hydrogenases are constitutively expressed), and display different sensitivity to O2 inactivation. Among various physiological factors, the sensitivity of hydrogenases to O2 has been one of the major factors preventing implementation of biological systems for commercial production of renewable H2. This review addresses recent strategies aimed at engineering increased O2 tolerance into hydrogenases (as of now mainly unsuccessful), as well as towards the development of methods to bypass the O2 sensitivity of hydrogenases (successful but still yielding low solar conversion efficiencies). The author concludes with a description of current approaches from various laboratories to incorporate multiple genetic traits into either algae or cyanobacteria to jointly address limiting factors other than the hydrogenase O2 sensitivity and achieve more sustained H2 photoproduction activity.
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Affiliation(s)
- Maria L Ghirardi
- National Renewable Energy Laboratory, 15013 Denver West Pkway, Golden, CO, 80401, USA,
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Cornish AJ, Green R, Gärtner K, Mason S, Hegg EL. Characterization of Hydrogen Metabolism in the Multicellular Green Alga Volvox carteri. PLoS One 2015; 10:e0125324. [PMID: 25927230 PMCID: PMC4416025 DOI: 10.1371/journal.pone.0125324] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 03/19/2015] [Indexed: 01/13/2023] Open
Abstract
Hydrogen gas functions as a key component in the metabolism of a wide variety of microorganisms, often acting as either a fermentative end-product or an energy source. The number of organisms reported to utilize hydrogen continues to grow, contributing to and expanding our knowledge of biological hydrogen processes. Here we demonstrate that Volvox carteri f. nagariensis, a multicellular green alga with differentiated cells, evolves H2 both when supplied with an abiotic electron donor and under physiological conditions. The genome of Volvox carteri contains two genes encoding putative [FeFe]-hydrogenases (HYDA1 and HYDA2), and the transcripts for these genes accumulate under anaerobic conditions. The HYDA1 and HYDA2 gene products were cloned, expressed, and purified, and both are functional [FeFe]-hydrogenases. Additionally, within the genome the HYDA1 and HYDA2 genes cluster with two putative genes which encode hydrogenase maturation proteins. This gene cluster resembles operon-like structures found within bacterial genomes and may provide further insight into evolutionary relationships between bacterial and algal [FeFe]-hydrogenase genes.
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Affiliation(s)
- Adam J. Cornish
- Great Lakes Bioenergy Research Center and the Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Robin Green
- Great Lakes Bioenergy Research Center and the Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Katrin Gärtner
- Great Lakes Bioenergy Research Center and the Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Saundra Mason
- Great Lakes Bioenergy Research Center and the Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
| | - Eric L. Hegg
- Great Lakes Bioenergy Research Center and the Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, Michigan, United States of America
- * E-mail:
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Rosenberg JN, Kobayashi N, Barnes A, Noel EA, Betenbaugh MJ, Oyler GA. Comparative analyses of three Chlorella species in response to light and sugar reveal distinctive lipid accumulation patterns in the Microalga C. sorokiniana. PLoS One 2014; 9:e92460. [PMID: 24699196 PMCID: PMC3974682 DOI: 10.1371/journal.pone.0092460] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 02/21/2014] [Indexed: 02/02/2023] Open
Abstract
While photosynthetic microalgae, such as Chlorella, serve as feedstocks for nutritional oils and biofuels, heterotrophic cultivation can augment growth rates, support high cell densities, and increase triacylglycerol (TAG) lipid content. However, these species differ significantly in their photoautotrophic and heterotrophic characteristics. In this study, the phylogeny of thirty Chlorella strains was determined in order to inform bioprospecting efforts and detailed physiological assessment of three species. The growth kinetics and lipid biochemistry of C. protothecoides UTEX 411, C. vulgaris UTEX 265, and C. sorokiniana UTEX 1230 were quantified during photoautotrophy in Bold's basal medium (BBM) and heterotrophy in BBM supplemented with glucose (10 g L−1). Heterotrophic growth rates of UTEX 411, 265, and 1230 were found to be 1.5-, 3.7-, and 5-fold higher than their respective autotrophic rates. With a rapid nine-hour heterotrophic doubling time, Chlorella sorokiniana UTEX 1230 maximally accumulated 39% total lipids by dry weight during heterotrophy compared to 18% autotrophically. Furthermore, the discrete fatty acid composition of each strain was examined in order to elucidate lipid accumulation patterns under the two trophic conditions. In both modes of growth, UTEX 411 and 265 produced 18∶1 as the principal fatty acid while UTEX 1230 exhibited a 2.5-fold enrichment in 18∶2 relative to 18∶1. Although the total lipid content was highest in UTEX 411 during heterotrophy, UTEX 1230 demonstrated a two-fold increase in its heterotrophic TAG fraction at a rate of 28.9 mg L−1 d−1 to reach 22% of the biomass, corresponding to as much as 90% of its total lipids. Interestingly, UTEX 1230 growth was restricted during mixotrophy and its TAG production rate was suppressed to 18.2 mg L−1 d−1. This constraint on carbon flow raises intriguing questions about the impact of sugar and light on the metabolic regulation of microalgal lipid biosynthesis.
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Affiliation(s)
- Julian N Rosenberg
- Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America; Synaptic Research LLC, Baltimore, Maryland, United States of America
| | - Naoko Kobayashi
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Austin Barnes
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Eric A Noel
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
| | - Michael J Betenbaugh
- Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - George A Oyler
- Department of Chemical & Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America; Synaptic Research LLC, Baltimore, Maryland, United States of America; Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, United States of America
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Skjånes K, Rebours C, Lindblad P. Potential for green microalgae to produce hydrogen, pharmaceuticals and other high value products in a combined process. Crit Rev Biotechnol 2013; 33:172-215. [PMID: 22765907 PMCID: PMC3665214 DOI: 10.3109/07388551.2012.681625] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Revised: 01/25/2012] [Accepted: 03/29/2012] [Indexed: 12/31/2022]
Abstract
Green microalgae for several decades have been produced for commercial exploitation, with applications ranging from health food for human consumption, aquaculture and animal feed, to coloring agents, cosmetics and others. Several products from green algae which are used today consist of secondary metabolites that can be extracted from the algal biomass. The best known examples are the carotenoids astaxanthin and β-carotene, which are used as coloring agents and for health-promoting purposes. Many species of green algae are able to produce valuable metabolites for different uses; examples are antioxidants, several different carotenoids, polyunsaturated fatty acids, vitamins, anticancer and antiviral drugs. In many cases, these substances are secondary metabolites that are produced when the algae are exposed to stress conditions linked to nutrient deprivation, light intensity, temperature, salinity and pH. In other cases, the metabolites have been detected in algae grown under optimal conditions, and little is known about optimization of the production of each product, or the effects of stress conditions on their production. Some green algae have shown the ability to produce significant amounts of hydrogen gas during sulfur deprivation, a process which is currently studied extensively worldwide. At the moment, the majority of research in this field has focused on the model organism, Chlamydomonas reinhardtii, but other species of green algae also have this ability. Currently there is little information available regarding the possibility for producing hydrogen and other valuable metabolites in the same process. This study aims to explore which stress conditions are known to induce the production of different valuable products in comparison to stress reactions leading to hydrogen production. Wild type species of green microalgae with known ability to produce high amounts of certain valuable metabolites are listed and linked to species with ability to produce hydrogen during general anaerobic conditions, and during sulfur deprivation. Species used today for commercial purposes are also described. This information is analyzed in order to form a basis for selection of wild type species for a future multi-step process, where hydrogen production from solar energy is combined with the production of valuable metabolites and other commercial uses of the algal biomass.
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Affiliation(s)
- Kari Skjånes
- Bioforsk - Norwegian Institute for Agricultural and Environmental Research, Fredrik A. Dahls vei 20, Ås, Norway.
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Meuser JE, Boyd ES, Ananyev G, Karns D, Radakovits R, Narayana Murthy UM, Ghirardi ML, Dismukes GC, Peters JW, Posewitz MC. Evolutionary significance of an algal gene encoding an [FeFe]-hydrogenase with F-domain homology and hydrogenase activity in Chlorella variabilis NC64A. PLANTA 2011; 234:829-43. [PMID: 21643991 DOI: 10.1007/s00425-011-1431-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2011] [Accepted: 05/06/2011] [Indexed: 05/20/2023]
Abstract
[FeFe]-hydrogenases (HYDA) link the production of molecular H(2) to anaerobic metabolism in many green algae. Similar to Chlamydomonas reinhardtii, Chlorella variabilis NC64A (Trebouxiophyceae, Chlorophyta) exhibits [FeFe]-hydrogenase (HYDA) activity during anoxia. In contrast to C. reinhardtii and other chlorophycean algae, which contain hydrogenases with only the HYDA active site (H-cluster), C. variabilis NC64A is the only known green alga containing HYDA genes encoding accessory FeS cluster-binding domains (F-cluster). cDNA sequencing confirmed the presence of F-cluster HYDA1 mRNA transcripts, and identified deviations from the in silico splicing models. We show that HYDA activity in C. variabilis NC64A is coupled to anoxic photosynthetic electron transport (PSII linked, as well as PSII-independent) and dark fermentation. We also show that the in vivo H(2)-photoproduction activity observed is as O(2) sensitive as in C. reinhardtii. The two C. variabilis NC64A HYDA sequences are similar to homologs found in more deeply branching bacteria (Thermotogales), diatoms, and heterotrophic flagellates, suggesting that an F-cluster HYDA is the ancestral enzyme in algae. Phylogenetic analysis indicates that the algal HYDA H-cluster domains are monophyletic, suggesting that they share a common origin, and evolved from a single ancestral F-cluster HYDA. Furthermore, phylogenetic reconstruction indicates that the multiple algal HYDA paralogs are the result of gene duplication events that occurred independently within each algal lineage. Collectively, comparative genomic, physiological, and phylogenetic analyses of the C. variabilis NC64A hydrogenase has provided new insights into the molecular evolution and diversity of algal [FeFe]-hydrogenases.
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Affiliation(s)
- Jonathan E Meuser
- Division of Environmental Science and Engineering, Colorado School of Mines, Golden, CO 80401, USA
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Grossman AR, Catalanotti C, Yang W, Dubini A, Magneschi L, Subramanian V, Posewitz MC, Seibert M. Multiple facets of anoxic metabolism and hydrogen production in the unicellular green alga Chlamydomonas reinhardtii. THE NEW PHYTOLOGIST 2011; 190:279-88. [PMID: 21563367 DOI: 10.1111/j.1469-8137.2010.03534.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Many microbes in the soil environment experience micro-oxic or anoxic conditions for much of the late afternoon and night, which inhibit or prevent respiratory metabolism. To sustain the production of energy and maintain vital cellular processes during the night, organisms have developed numerous pathways for fermentative metabolism. This review discusses fermentation pathways identified for the soil-dwelling model alga Chlamydomonas reinhardtii, its ability to produce molecular hydrogen under anoxic conditions through the activity of hydrogenases, and the molecular flexibility associated with fermentative metabolism that has only recently been revealed through the analysis of specific mutant strains.
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Affiliation(s)
- Arthur R Grossman
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA.
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Burgess SJ, Tamburic B, Zemichael F, Hellgardt K, Nixon PJ. Solar-driven hydrogen production in green algae. ADVANCES IN APPLIED MICROBIOLOGY 2011; 75:71-110. [PMID: 21807246 DOI: 10.1016/b978-0-12-387046-9.00004-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The twin problems of energy security and global warming make hydrogen an attractive alternative to traditional fossil fuels with its combustion resulting only in the release of water vapor. Biological hydrogen production represents a renewable source of the gas and can be performed by a diverse range of microorganisms from strict anaerobic bacteria to eukaryotic green algae. Compared to conventional methods for generating H(2), biological systems can operate at ambient temperatures and pressures without the need for rare metals and could potentially be coupled to a variety of biotechnological processes ranging from desalination and waste water treatment to pharmaceutical production. Photobiological hydrogen production by microalgae is particularly attractive as the main inputs for the process (water and solar energy) are plentiful. This chapter focuses on recent developments in solar-driven H(2) production in green algae with emphasis on the model organism Chlamydomonas reinhardtii. We review the current methods used to achieve sustained H(2) evolution and discuss possible approaches to improve H(2) yields, including the optimization of culturing conditions, reducing light-harvesting antennae and targeting auxiliary electron transport and fermentative pathways that compete with the hydrogenase for reductant. Finally, industrial scale-up is discussed in the context of photobioreactor design and the future prospects of the field are considered within the broader context of a biorefinery concept.
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Affiliation(s)
- Steven J Burgess
- Department of Life Sciences, Imperial College London, London, United Kingdom.
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Timmins M, Thomas-Hall SR, Darling A, Zhang E, Hankamer B, Marx UC, Schenk PM. Phylogenetic and molecular analysis of hydrogen-producing green algae. JOURNAL OF EXPERIMENTAL BOTANY 2009; 60:1691-702. [PMID: 19342428 PMCID: PMC2671627 DOI: 10.1093/jxb/erp052] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
A select set of microalgae are reported to be able to catalyse photobiological H(2) production from water. Based on the model organism Chlamydomonas reinhardtii, a method was developed for the screening of naturally occurring H(2)-producing microalgae. By purging algal cultures with N(2) in the dark and subsequent illumination, it is possible to rapidly induce photobiological H(2) evolution. Using NMR spectroscopy for metabolic profiling in C. reinhardtii, acetate, formate, and ethanol were found to be key compounds contributing to metabolic variance during the assay. This procedure can be used to test algal species existing as axenic or mixed cultures for their ability to produce H(2). Using this system, five algal isolates capable of H(2) production were identified in various aquatic systems. A phylogenetic tree was constructed using ribosomal sequence data of green unicellular algae to determine if there were taxonomic patterns of H(2) production. H(2)-producing algal species were seen to be dispersed amongst most clades, indicating an H(2)-producing capacity preceded evolution of the phylum Chlorophyta.
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Affiliation(s)
- Matthew Timmins
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Skye R. Thomas-Hall
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Aaron Darling
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Eugene Zhang
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Ben Hankamer
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Ute C. Marx
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland 4072, Australia
- SRC for Functional and Applied Genomics, The University of Queensland, St Lucia, Queensland 4072, Australia
| | - Peer M. Schenk
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland 4072, Australia
- To whom correspondence should be addressed: E-mail:
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Chang CH, King PW, Ghirardi ML, Kim K. Atomic resolution modeling of the ferredoxin:[FeFe] hydrogenase complex from Chlamydomonas reinhardtii. Biophys J 2007; 93:3034-45. [PMID: 17660315 PMCID: PMC2025642 DOI: 10.1529/biophysj.107.108589] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Accepted: 07/06/2007] [Indexed: 11/18/2022] Open
Abstract
The [FeFe] hydrogenases HydA1 and HydA2 in the green alga Chlamydomonas reinhardtii catalyze the final reaction in a remarkable metabolic pathway allowing this photosynthetic organism to produce H(2) from water in the chloroplast. A [2Fe-2S] ferredoxin is a critical branch point in electron flow from Photosystem I toward a variety of metabolic fates, including proton reduction by hydrogenases. To better understand the binding determinants involved in ferredoxin:hydrogenase interactions, we have modeled Chlamydomonas PetF1 and HydA2 based on amino-acid sequence homology, and produced two promising electron-transfer model complexes by computational docking. To characterize these models, quantitative free energy calculations at atomic resolution were carried out, and detailed analysis of the interprotein interactions undertaken. The protein complex model we propose for ferredoxin:HydA2 interaction is energetically favored over the alternative candidate by 20 kcal/mol. This proposed model of the electron-transfer complex between PetF1 and HydA2 permits a more detailed view of the molecular events leading up to H(2) evolution, and suggests potential mutagenic strategies to modulate electron flow to HydA2.
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Ghirardi ML, Posewitz MC, Maness PC, Dubini A, Yu J, Seibert M. Hydrogenases and hydrogen photoproduction in oxygenic photosynthetic organisms. ANNUAL REVIEW OF PLANT BIOLOGY 2007; 58:71-91. [PMID: 17150028 DOI: 10.1146/annurev.arplant.58.032806.103848] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The photobiological production of H2 gas, using water as the only electron donor, is a property of two types of photosynthetic microorganisms: green algae and cyanobacteria. In these organisms, photosynthetic water splitting is functionally linked to H(2) production by the activity of hydrogenase enzymes. Interestingly, each of these organisms contains only one of two major types of hydrogenases, [FeFe] or [NiFe] enzymes, which are phylogenetically distinct but perform the same catalytic reaction, suggesting convergent evolution. This idea is supported by the observation that each of the two classes of hydrogenases has a different metallo-cluster, is encoded by entirely different sets of genes (apparently under the control of different promoter elements), and exhibits different maturation pathways. The genetics, biosynthesis, structure, function, and O2 sensitivity of these enzymes have been the focus of extensive research in recent years. Some of this effort is clearly driven by the potential for using these enzymes in future biological or biohybrid systems to produce renewable fuel or in fuel cell applications.
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Melis A, Seibert M, Happe T. Genomics of green algal hydrogen research. PHOTOSYNTHESIS RESEARCH 2004; 82:277-88. [PMID: 16143840 DOI: 10.1007/s11120-004-2050-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Accepted: 07/16/2004] [Indexed: 05/04/2023]
Abstract
This article summarizes knowledge on genes and their respective proteins in the field of green algal hydrogen research. Emphasis is placed on recently cloned genes from the unicellular green alga Chlamydomonas reinhardtii, including HydA1 and HydA2, which encode homologous [Fe]-hydrogenases, Tla1, which encodes a chlorophyll antenna size regulatory gene, SulP, which encodes a chloroplast sulfate permease, and Sta7, which encodes an isoamylase. Analysis of the structure and function of these genes and of their respective proteins in C. reinhardtii, and related unicellular green algae, is presented in light of the role they play in the hydrogen metabolism in these organisms. A discussion is offered as to the potential application of these genes in the field of hydrogen photoproduction.
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Affiliation(s)
- Anastasios Melis
- Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA, 94720-3102, USA,
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Forestier M, King P, Zhang L, Posewitz M, Schwarzer S, Happe T, Ghirardi ML, Seibert M. Expression of two [Fe]-hydrogenases in Chlamydomonas reinhardtii under anaerobic conditions. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:2750-8. [PMID: 12823545 DOI: 10.1046/j.1432-1033.2003.03656] [Citation(s) in RCA: 202] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have isolated and characterized a second [Fe]-hydrogenase gene from the green alga, Chlamydomonas reinhardtii. The HydA2 gene encodes a protein of 505 amino acids that is 74% similar and 68% identical to the known HydA1 hydrogenase from C. reinhardtii. HydA2 contains all the conserved residues and motifs found in the catalytic core of the family of [Fe]-hydrogenases. We demonstrate that both the HydA1 and the HydA2 transcripts are expressed upon anaerobic induction, achieved either by neutral gas purging or by sulfur deprivation of the cultures. Furthermore, the expression levels of both transcripts are regulated (in some cases differently) by incubation conditions, such as the length of anaerobiosis, the readdition of O2, the presence of acetate, and/or the absence of nutrients such as sulfate during growth. Antibodies specific for HydA2 recognized a protein of about 49 kDa in extracts from anaerobically induced C. reinhardtii cells, strongly suggesting that HydA2 encodes for an expressed protein. Homology-based 3D modeling of the HydA2 hydrogenase shows that its catalytic site models well to the known structure of Clostridium pasteurianum CpI, including the H2-gas channel. The major differences between HydA1, HydA2 and CpI are the absence of the N-terminal Fe-S centers and the existence of extra sequences in the algal enzymes. To our knowledge, this work represents the first systematic study of expression of two algal [Fe]-hydrogenases in the same organism.
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Affiliation(s)
- Marc Forestier
- National Renewable Energy Laboratory, Golden, CO 80401, USA
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14
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Przybyla AE, Robbins J, Menon N, Peck HD. Structure-function relationships among the nickel-containing hydrogenases. FEMS Microbiol Rev 1992; 8:109-35. [PMID: 1558764 DOI: 10.1111/j.1574-6968.1992.tb04960.x] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The enzymology of the heterodimeric (NiFe) and (NiFeSe) hydrogenases, the monomeric nickel-containing hydrogenases plus the multimeric F420-(NiFe) and NAD(+)-(NiFe) hydrogenases are summarized and discussed in terms of subunit localization of the redox-active nickel and non-heme iron clusters. It is proposed that nickel is ligated solely by amino acid residues of the large subunit and that the non-heme iron clusters are ligated by other cysteine-rich polypeptides encoded in the hydrogenase operons which are not necessarily homologous in either structure or function. Comparison of the hydrogenase operons or putative operons and their hydrogenase genes indicate that the arrangement, number and types of genes in these operons are not conserved among the various types of hydrogenases except for the gene encoding the large subunit. Thus, the presence of the gene for the large subunit is the sole feature common to all known nickel-containing hydrogenases and unites these hydrogenases into a large but diverse gene family. Although the different genes for the large subunits may possess only nominal general derived amino acid homology, all large subunit genes sequenced to date have the sequence R-X-C-X-X-C fully conserved in the amino terminal region of the polypeptide chain and the sequence of D-P-C-X-X-C fully conserved in the carboxyl terminal region. It is proposed that these conserved motifs of amino acids provide the ligands required for the binding of the redox-active nickel. The existing EXAFS (Extended X-ray Absorption Fine Structure) information is summarized and discussed in terms of the numbers and types of ligands to the nickel and the various redox species of nickel defined by EPR spectroscopy. New information concerning the ligands to nickel is presented based on site-directed mutagenesis of the gene encoding the large subunit of the (NiFe) hydrogenase-1 of Escherichia coli. Based on considerations of the biochemical, molecular and biophysical information, ligand environments of the nickel in different redox states of the (NiFe) hydrogenase are proposed.
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Affiliation(s)
- A E Przybyla
- Department of Biochemistry, University of Georgia, Athens 30602
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15
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Krogmann DW. The low-potential cytochrome c of cyanobacteria and algae. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1058:35-7. [PMID: 1646015 DOI: 10.1016/s0005-2728(05)80264-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A water-soluble, low-potential cytochrome c-550 is found in some cyanobacteria and eukaryotic algae and has regions of sequence similarity to cytochrome c6. This cytochrome appears to be involved in a fermentation that sustains the organisms during prolonged periods of dark, anaerobic conditions.
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Affiliation(s)
- D W Krogmann
- Department of Biochemistry, Purdue University, West Lafayette, IN
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