1
|
Chu G, Wang Q, Song C, Liu J, Zhao Y, Lu S, Zhang Z, Jin C, Gao M. Platymonas helgolandica-driven nitrogen removal from mariculture wastewater under different photoperiods: Performance evaluation, enzyme activity and transcriptional response. BIORESOURCE TECHNOLOGY 2023; 372:128700. [PMID: 36738978 DOI: 10.1016/j.biortech.2023.128700] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 01/30/2023] [Accepted: 01/31/2023] [Indexed: 06/18/2023]
Abstract
The nitrogen removal performance and biological mechanism of Platymonas helgolandica var. Tsingtaoensis (P. helgolandica) were investigated in treating mariculture wastewater under different light: dark (L:D) photoperiods. The growth of P. helgolandica was positively correlated with the photoperiods from 6L:18D to 15L:9D, and the highest photosynthetic activity appeared under 6L:18D photoperiod on day 3. P. helgolandica exhibited the highest removal efficiencies of total nitrogen and COD at 89 % and 93 % under 15L:9D photoperiod, respectively. NH4+-N assimilation was proportional to the photoperiods from 6L:18D to 15L:9D and longer illumination promoted NO2--N removal. However, the highest NO3--N reduction rate was achieved under 12L:12D photoperiod. The different nitrogen-transformed enzymatic activities were affected by photoperiod. Transcriptome revealed that unigenes were enriched in nitrogen metabolism and photosynthesis pathways, of which the functional gene expression was up-regulated significantly. This study provides insights into the optimization of photoperiod for mariculture wastewater treatment by P. helgolandica.
Collapse
Affiliation(s)
- Guangyu Chu
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Qianzhi Wang
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Chenguang Song
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Jiateng Liu
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Yangguo Zhao
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao 266100, China
| | - Shuailing Lu
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China; College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
| | - Zhiming Zhang
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Chunji Jin
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China
| | - Mengchun Gao
- Key Lab of Marine Environment and Ecology, Ministry of Education, Ocean University of China, Qingdao 266100, China; Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, Ocean University of China, Qingdao 266100, China.
| |
Collapse
|
2
|
Panwar P, Allen MA, Williams TJ, Haque S, Brazendale S, Hancock AM, Paez-Espino D, Cavicchioli R. Remarkably coherent population structure for a dominant Antarctic Chlorobium species. MICROBIOME 2021; 9:231. [PMID: 34823595 PMCID: PMC8620254 DOI: 10.1186/s40168-021-01173-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Accepted: 10/09/2021] [Indexed: 05/22/2023]
Abstract
BACKGROUND In Antarctica, summer sunlight enables phototrophic microorganisms to drive primary production, thereby "feeding" ecosystems to enable their persistence through the long, dark winter months. In Ace Lake, a stratified marine-derived system in the Vestfold Hills of East Antarctica, a Chlorobium species of green sulphur bacteria (GSB) is the dominant phototroph, although its seasonal abundance changes more than 100-fold. Here, we analysed 413 Gb of Antarctic metagenome data including 59 Chlorobium metagenome-assembled genomes (MAGs) from Ace Lake and nearby stratified marine basins to determine how genome variation and population structure across a 7-year period impacted ecosystem function. RESULTS A single species, Candidatus Chlorobium antarcticum (most similar to Chlorobium phaeovibrioides DSM265) prevails in all three aquatic systems and harbours very little genomic variation (≥ 99% average nucleotide identity). A notable feature of variation that did exist related to the genomic capacity to biosynthesize cobalamin. The abundance of phylotypes with this capacity changed seasonally ~ 2-fold, consistent with the population balancing the value of a bolstered photosynthetic capacity in summer against an energetic cost in winter. The very high GSB concentration (> 108 cells ml-1 in Ace Lake) and seasonal cycle of cell lysis likely make Ca. Chlorobium antarcticum a major provider of cobalamin to the food web. Analysis of Ca. Chlorobium antarcticum viruses revealed the species to be infected by generalist (rather than specialist) viruses with a broad host range (e.g., infecting Gammaproteobacteria) that were present in diverse Antarctic lakes. The marked seasonal decrease in Ca. Chlorobium antarcticum abundance may restrict specialist viruses from establishing effective lifecycles, whereas generalist viruses may augment their proliferation using other hosts. CONCLUSION The factors shaping Antarctic microbial communities are gradually being defined. In addition to the cold, the annual variation in sunlight hours dictates which phototrophic species can grow and the extent to which they contribute to ecosystem processes. The Chlorobium population studied was inferred to provide cobalamin, in addition to carbon, nitrogen, hydrogen, and sulphur cycling, as critical ecosystem services. The specific Antarctic environmental factors and major ecosystem benefits afforded by this GSB likely explain why such a coherent population structure has developed in this Chlorobium species. Video abstract.
Collapse
Affiliation(s)
- Pratibha Panwar
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Michelle A Allen
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Timothy J Williams
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Sabrina Haque
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Present address: Department of Molecular Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia
| | - Sarah Brazendale
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- , Present address: Pegarah, Australia
| | - Alyce M Hancock
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Present address: Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, Tasmania, Australia
| | - David Paez-Espino
- Department of Energy Joint Genome Institute, Berkeley, CA, USA
- Present address: Mammoth Biosciences, Inc., 1000 Marina Blvd. Suite 600, Brisbane, CA, USA
| | - Ricardo Cavicchioli
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney, Sydney, New South Wales, 2052, Australia.
| |
Collapse
|
3
|
Yue H, Zhao C, Yang S, Jia Y. Effects of glycine on cell growth and pigment biosynthesis in Rhodobacter azotoformans. J Basic Microbiol 2020; 61:63-73. [PMID: 33226142 DOI: 10.1002/jobm.202000503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Revised: 10/09/2020] [Accepted: 10/24/2020] [Indexed: 11/07/2022]
Abstract
The effect of exogenous glycine (a precursor for the biosynthesis of bacteriochlorophyll) on the cell growth and photopigment accumulation was investigated in phototrophic growing Rhodobacter azotoformans 134K20. The growth rate and the biomass of strain 134K20 were significantly inhibited by glycine addition when ammonium sulfate or glutamate were used as nitrogen sources and acetate or succinate as carbon sources. A characteristic absorption maximum at approximately 423 nm was present in the absorption spectra of glutamate cultures while it was absent by the addition of high-concentration glycine of 15 mM. The component account for the 423 nm peak was eventually identified as magnesium protoporphyrin IX monomethyl ester, a precursor of bacteriochlorophyll a (BChl a). Comparative analysis of pigment composition revealed that the amount of BChl a precursors was significantly decreased by the addition of 15-mM glycine while the BChl a accumulation was increased. Moreover, glycine changed the carotenoid compositions and stimulated the accumulation of spheroidene. The A850 /A875 in the growth-inhibited cultures was increased, indicating an increased level of the light-harvesting complex 2 compared to the reaction center. The exogenous glycine possibly played an important regulation role in photosynthesis of purple bacteria.
Collapse
Affiliation(s)
- Huiying Yue
- College of Basic Medical Sciences, Shanxi University of Chinese Medicine, Taiyuan, China
- Department of Bioengineering and Biotechnology, Huaqiao University, Xiamen, China
| | - Chungui Zhao
- Department of Bioengineering and Biotechnology, Huaqiao University, Xiamen, China
| | - Suping Yang
- Department of Bioengineering and Biotechnology, Huaqiao University, Xiamen, China
| | - Yaqiong Jia
- Department of Bioengineering and Biotechnology, Huaqiao University, Xiamen, China
| |
Collapse
|
4
|
Chen X, Wang X, Feng J, Chen Y, Fang Y, Zhao S, Zhao A, Zhang M, Liu L. Structural insights into the catalytic mechanism of Synechocystis magnesium protoporphyrin IX O-methyltransferase (ChlM). J Biol Chem 2014; 289:25690-8. [PMID: 25077963 DOI: 10.1074/jbc.m114.584920] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Magnesium protoporphyrin IX O-methyltransferase (ChlM) catalyzes transfer of the methyl group from S-adenosylmethionine to the carboxyl group of the C13 propionate side chain of magnesium protoporphyrin IX. This reaction is the second committed step in chlorophyll biosynthesis from protoporphyrin IX. Here we report the crystal structures of ChlM from the cyanobacterium Synechocystis sp. PCC 6803 in complex with S-adenosylmethionine and S-adenosylhomocysteine at resolutions of 1.6 and 1.7 Å, respectively. The structures illustrate the molecular basis for cofactor and substrate binding and suggest that conformational changes of the two "arm" regions may modulate binding and release of substrates/products to and from the active site. Tyr-28 and His-139 were identified to play essential roles for methyl transfer reaction but are not indispensable for cofactor/substrate binding. Based on these structural and functional findings, a catalytic model is proposed.
Collapse
Affiliation(s)
- Xuemin Chen
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, the University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiao Wang
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, the University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Juan Feng
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, the University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yuhong Chen
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Ying Fang
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, the University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shun Zhao
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, the University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Aiguo Zhao
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China, the University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Min Zhang
- the Engineering Research Center for Biomedical Materials, School of Life Sciences, Anhui University, Hefei, Anhui, 230601, China, and
| | - Lin Liu
- From the Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China,
| |
Collapse
|
5
|
Tikh IB, Quin MB, Schmidt-Dannert C. A tale of two reductases: extending the bacteriochlorophyll biosynthetic pathway in E. coli. PLoS One 2014; 9:e89734. [PMID: 24586995 PMCID: PMC3931815 DOI: 10.1371/journal.pone.0089734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Accepted: 01/23/2014] [Indexed: 12/23/2022] Open
Abstract
The creation of a synthetic microbe that can harvest energy from sunlight to drive its metabolic processes is an attractive approach to the economically viable biosynthetic production of target compounds. Our aim is to design and engineer a genetically tractable non-photosynthetic microbe to produce light-harvesting molecules. Previously we created a modular, multienzyme system for the heterologous production of intermediates of the bacteriochlorophyll (BChl) pathway in E. coli. In this report we extend this pathway to include a substrate promiscuous 8-vinyl reductase that can accept multiple intermediates of BChl biosynthesis. We present an informative comparative analysis of homologues of 8-vinyl reductase from the model photosynthetic organisms Rhodobacter sphaeroides and Chlorobaculum tepidum. The first purification of the enzymes leads to their detailed biochemical and biophysical characterization. The data obtained reveal that the two 8-vinyl reductases are substrate promiscuous, capable of reducing the C8-vinyl group of Mg protoporphyrin IX, Mg protoporphyrin IX methylester, and divinyl protochlorophyllide. However, activity is dependent upon the presence of chelated Mg2+ in the porphyrin ring, with no activity against non-Mg2+ chelated intermediates observed. Additionally, CD analyses reveal that the two 8-vinyl reductases appear to bind the same substrate in a different fashion. Furthermore, we discover that the different rates of reaction of the two 8-vinyl reductases both in vitro, and in vivo as part of our engineered system, results in the suitability of only one of the homologues for our BChl pathway in E. coli. Our results offer the first insights into the different functionalities of homologous 8-vinyl reductases. This study also takes us one step closer to the creation of a nonphotosynthetic microbe that is capable of harvesting energy from sunlight for the biosynthesis of molecules of choice.
Collapse
Affiliation(s)
- Ilya B. Tikh
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Maureen B. Quin
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, United States of America
| | - Claudia Schmidt-Dannert
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, United States of America
- * E-mail:
| |
Collapse
|
6
|
Sousa FL, Shavit-Grievink L, Allen JF, Martin WF. Chlorophyll biosynthesis gene evolution indicates photosystem gene duplication, not photosystem merger, at the origin of oxygenic photosynthesis. Genome Biol Evol 2013; 5:200-16. [PMID: 23258841 PMCID: PMC3595025 DOI: 10.1093/gbe/evs127] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
An open question regarding the evolution of photosynthesis is how cyanobacteria came to possess the two reaction center (RC) types, Type I reaction center (RCI) and Type II reaction center (RCII). The two main competing theories in the foreground of current thinking on this issue are that either 1) RCI and RCII are related via lineage divergence among anoxygenic photosynthetic bacteria and became merged in cyanobacteria via an event of large-scale lateral gene transfer (also called "fusion" theories) or 2) the two RC types are related via gene duplication in an ancestral, anoxygenic but protocyanobacterial phototroph that possessed both RC types before making the transition to using water as an electron donor. To distinguish between these possibilities, we studied the evolution of the core (bacterio)chlorophyll biosynthetic pathway from protoporphyrin IX (Proto IX) up to (bacterio)chlorophyllide a. The results show no dichotomy of chlorophyll biosynthesis genes into RCI- and RCII-specific chlorophyll biosynthetic clades, thereby excluding models of fusion at the origin of cyanobacteria and supporting the selective-loss hypothesis. By considering the cofactor demands of the pathway and the source genes from which several steps in chlorophyll biosynthesis are derived, we infer that the cell that first synthesized chlorophyll was a cobalamin-dependent, heme-synthesizing, diazotrophic anaerobe.
Collapse
Affiliation(s)
- Filipa L Sousa
- Institute of Molecular Evolution, University of Düsseldorf, Düsseldorf, Germany.
| | | | | | | |
Collapse
|
7
|
Towards Engineered Light–Energy Conversion in Nonphotosynthetic Microorganisms. Synth Biol (Oxf) 2013. [DOI: 10.1016/b978-0-12-394430-6.00016-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] Open
|
8
|
Qian P, Marklew CJ, Viney J, Davison PA, Brindley AA, Söderberg C, Al-Karadaghi S, Bullough PA, Grossmann JG, Hunter CN. Structure of the cyanobacterial Magnesium Chelatase H subunit determined by single particle reconstruction and small-angle X-ray scattering. J Biol Chem 2012; 287:4946-56. [PMID: 22179610 PMCID: PMC3281664 DOI: 10.1074/jbc.m111.308239] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 12/07/2011] [Indexed: 02/02/2023] Open
Abstract
The biosynthesis of chlorophyll, an essential cofactor for photosynthesis, requires the ATP-dependent insertion of Mg(2+) into protoporphyrin IX catalyzed by the multisubunit enzyme magnesium chelatase. This enzyme complex consists of the I subunit, an ATPase that forms a complex with the D subunit, and an H subunit that binds both the protoporphyrin substrate and the magnesium protoporphyrin product. In this study we used electron microscopy and small-angle x-ray scattering to investigate the structure of the magnesium chelatase H subunit, ChlH, from the thermophilic cyanobacterium Thermosynechococcus elongatus. Single particle reconstruction of negatively stained apo-ChlH and Chl-porphyrin proteins was used to reconstitute three-dimensional structures to a resolution of ∼30 Å. ChlH is a large, 148-kDa protein of 1326 residues, forming a cage-like assembly comprising the majority of the structure, attached to a globular N-terminal domain of ∼16 kDa by a narrow linker region. This N-terminal domain is adjacent to a 5 nm-diameter opening in the structure that allows access to a cavity. Small-angle x-ray scattering analysis of ChlH, performed on soluble, catalytically active ChlH, verifies the presence of two domains and their relative sizes. Our results provide a basis for the multiple regulatory and catalytic functions of ChlH of oxygenic photosynthetic organisms and for a chaperoning function that sequesters the enzyme-bound magnesium protoporphyrin product prior to its delivery to the next enzyme in the chlorophyll biosynthetic pathway, magnesium protoporphyrin methyltransferase.
Collapse
Affiliation(s)
- Pu Qian
- From the Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Christopher J. Marklew
- From the Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Joanne Viney
- From the Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Paul A. Davison
- From the Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Amanda A. Brindley
- From the Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Christopher Söderberg
- the Department of Molecular Biophysics, Center for Molecular Protein Science, Lund University, 22100 Lund, Sweden, and
| | - Salam Al-Karadaghi
- the Department of Molecular Biophysics, Center for Molecular Protein Science, Lund University, 22100 Lund, Sweden, and
| | - Per A. Bullough
- From the Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - J. Günter Grossmann
- the Molecular Biophysics Group, Institute of Integrative Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - C. Neil Hunter
- From the Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| |
Collapse
|
9
|
Czarnecki O, Grimm B. Post-translational control of tetrapyrrole biosynthesis in plants, algae, and cyanobacteria. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:1675-87. [PMID: 22231500 DOI: 10.1093/jxb/err437] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The tetrapyrrole biosynthetic pathway provides the vital cofactors and pigments for photoautotrophic growth (chlorophyll), several essential redox reactions in electron transport chains (haem), N- and S-assimilation (sirohaem), and photomorphogenic processes (phytochromobilin). While the biochemistry of the pathway is well understood and almost all genes encoding enzymes of tetrapyrrole biosynthesis have been identified in plants, the post-translational control and organization of the pathway remains to be clarified. Post-translational mechanisms controlling metabolic activities are of particular interest since tetrapyrrole biosynthesis needs adaptation to environmental challenges. This review surveys post-translational mechanisms that have been reported to modulate metabolic activities and organization of the tetrapyrrole biosynthesis pathway.
Collapse
Affiliation(s)
- Olaf Czarnecki
- Institute of Biology/Plant Physiology, Humboldt-Universität zu Berlin, Philippstr. 13, Building 12, 10115 Berlin, Germany
| | | |
Collapse
|
10
|
CarF mediates signaling by singlet oxygen, generated via photoexcited protoporphyrin IX, in Myxococcus xanthus light-induced carotenogenesis. J Bacteriol 2012; 194:1427-36. [PMID: 22267513 DOI: 10.1128/jb.06662-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Blue light triggers carotenogenesis in the nonphototrophic bacterium Myxococcus xanthus by inducing inactivation of an anti-σ factor, CarR, and the consequent liberation of the cognate extracytoplasmic function (ECF) σ factor, CarQ. CarF, the protein implicated earliest in the response to light, does not resemble any known photoreceptor. It interacts physically with CarR and is required for its light-driven inactivation, but the mechanism is unknown. Blue-light sensing in M. xanthus has been attributed to the heme precursor protoporphyrin IX (PPIX), which can generate the highly reactive singlet oxygen species ((1)O(2)) by energy transfer to oxygen. However, (1)O(2) involvement in M. xanthus light-induced carotenogenesis remains to be established. Here, we present genetic evidence of the involvement of PPIX as well as (1)O(2) in light-induced carotenogenesis in M. xanthus and of how these are linked to CarF in the signal transduction pathway. Response to light was examined in carF-bearing and carF-deficient M. xanthus strains lacking endogenous PPIX due to deletion of hemB or accumulating PPIX due to deletion of hemH (hemB and hemH are early- and late-acting heme biosynthesis genes, respectively). This demonstrated that light induction of the CarQ-dependent promoter, P(QRS), correlated directly with cellular PPIX levels. Furthermore, we show that P(QRS) activation is triggered by (1)O(2) and is inhibited by exogenously supplied hemin and that CarF is essential for the action of (1)O(2). Thus, our findings indicate that blue light interaction with PPIX generates (1)O(2), which must be transmitted via CarF to trigger the transcriptional response underlying light-induced carotenogenesis in M. xanthus.
Collapse
|
11
|
Comparative and Functional Genomics of Anoxygenic Green Bacteria from the Taxa Chlorobi, Chloroflexi, and Acidobacteria. FUNCTIONAL GENOMICS AND EVOLUTION OF PHOTOSYNTHETIC SYSTEMS 2012. [DOI: 10.1007/978-94-007-1533-2_3] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
12
|
Sawicki A, Willows RD. BchJ and BchM interact in a 1 : 1 ratio with the magnesium chelatase BchH subunit of Rhodobacter capsulatus. FEBS J 2010; 277:4709-21. [PMID: 20955518 DOI: 10.1111/j.1742-4658.2010.07877.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Substrate channeling between the enzymatic steps in the (bacterio)chlorophyll biosynthetic pathway catalyzed by magnesium chelatase (BchI/ChlI, BchD/ChlD and BchH/ChlH subunits) and S-adenosyl-L-methionine:magnesium-protoporphyrin IX O-methyltransferase (BchM/ChlM) has been suggested. This involves delivery of magnesium-protoporphyrin IX from the BchH/ChlH subunit of magnesium chelatase to BchM/ChlM. Stimulation of BchM/ChlM activity by BchH/ChlH has previously been shown, and physical interaction of the two proteins has been demonstrated. In plants and cyanobacteria, there is an added layer of complexity, as Gun4 serves as a porphyrin (protoporphyrin IX and magnesium-protoporphyrin IX) carrier, but this protein does not exist in anoxygenic photosynthetic bacteria. BchJ may play a similar role to Gun4 in Rhodobacter, as it has no currently assigned function in the established pathway. Purified recombinant Rhodobacter capsulatus BchJ and BchM were found to cause a shift in the equilibrium amount of Mg-protoporphyrin IX formed in a magnesium chelatase assay. Analysis of this shift revealed that it was always in a 1 : 1 ratio with either of these proteins and the BchH subunit of the magnesium chelatase. The establishment of the new equilibrium was faster with BchM than with BchJ in a coupled magnesium chelatase assay. BchJ bound magnesium-protoporphyrin IX or formed a ternary complex with BchH and magnesium-protoporphyrin IX. These results suggest that BchJ may play a role as a general magnesium porphyrin carrier, similar to one of the roles of GUN4 in oxygenic organisms.
Collapse
Affiliation(s)
- Artur Sawicki
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW, Australia
| | | |
Collapse
|
13
|
Stenbaek A, Jensen PE. Redox regulation of chlorophyll biosynthesis. PHYTOCHEMISTRY 2010; 71:853-859. [PMID: 20417532 DOI: 10.1016/j.phytochem.2010.03.022] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 03/30/2010] [Accepted: 03/31/2010] [Indexed: 05/29/2023]
Abstract
Chlorophyll captures and redirects light-energy and is thus essential for photosynthetic organisms. The demand for chlorophyll differs throughout the day and night and in response to changing light conditions. Moreover, the chlorophyll biosynthesis pathway is up to certain points shared between the different tetrapyrroles; chlorophyll, heme, siroheme and phytochromobilin, for which the cell has different requirements at different time points. Combined with the phototoxic properties of tetrapyrroles which, if not properly protected, can lead to formation of reactive oxygen species (ROS), the need for a strict regulation of the chlorophyll biosynthetic pathway is obvious. Here we describe the current knowledge on regulation of chlorophyll biosynthesis in plants by the chloroplast redox state with emphasis on the Mg-chelatase situated at the branch point between the heme and the chlorophyll pathway. We discuss the proposed role of the Mg-chelatase as a key regulator of the tetrapyrrole pathway by its effect on enzymes both up- and downstream in the pathway and we specifically describe how redox state might regulate the Mg-branch. Finally, we propose that a recently identified NADPH-dependent thioredoxin reductase (NTRC) could be involved in redox regulation or protection of chlorophyll biosynthetic enzymes and describe the possible modes of action by this enzyme.
Collapse
Affiliation(s)
- Anne Stenbaek
- VKR Research Centre Pro-Active Plants, Department of Plant Biology and Biotechnology, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | | |
Collapse
|
14
|
Adhikari ND, Orler R, Chory J, Froehlich JE, Larkin RM. Porphyrins promote the association of GENOMES UNCOUPLED 4 and a Mg-chelatase subunit with chloroplast membranes. J Biol Chem 2009; 284:24783-96. [PMID: 19605356 PMCID: PMC2757182 DOI: 10.1074/jbc.m109.025205] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Revised: 05/26/2009] [Indexed: 11/29/2022] Open
Abstract
In plants, chlorophylls and other tetrapyrroles are synthesized from a branched pathway that is located within chloroplasts. GUN4 (GENOMES UNCOUPLED 4) stimulates chlorophyll biosynthesis by activating Mg-chelatase, the enzyme that commits porphyrins to the chlorophyll branch. GUN4 stimulates Mg-chelatase by a mechanism that involves binding the ChlH subunit of Mg-chelatase, as well as a substrate (protoporphyrin IX) and product (Mg-protoporphyrin IX) of Mg-chelatase. We chose to test whether GUN4 might also affect interactions between Mg-chelatase and chloroplast membranes, the site of chlorophyll biosynthesis. To test this idea, we induced chlorophyll precursor levels in purified pea chloroplasts by feeding these chloroplasts with 5-aminolevulinic acid, determined the relative levels of GUN4 and Mg-chelatase subunits in soluble and membrane-containing fractions derived from these chloroplasts, and quantitated Mg-chelatase activity in membranes isolated from these chloroplasts. We also monitored GUN4 levels in the soluble and membrane-containing fractions derived from chloroplasts fed with various porphyrins. Our results indicate that 5-aminolevulinic acid feeding stimulates Mg-chelatase activity in chloroplast membranes and that the porphyrin-bound forms of GUN4 and possibly ChlH associate most stably with chloroplast membranes. These findings are consistent with GUN4 stimulating chlorophyll biosynthesis not only by activating Mg-chelatase but also by promoting interactions between ChlH and chloroplast membranes.
Collapse
Affiliation(s)
- Neil D. Adhikari
- From the Department of Energy Plant Research Laboratory
- Genetics Program, and
| | - Robert Orler
- From the Department of Energy Plant Research Laboratory
| | - Joanne Chory
- the Howard Hughes Medical Institute and Plant Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037
| | | | - Robert M. Larkin
- From the Department of Energy Plant Research Laboratory
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824 and
| |
Collapse
|
15
|
Gomez Maqueo Chew A, Frigaard NU, Bryant DA. Mutational analysis of three bchH paralogs in (bacterio-)chlorophyll biosynthesis in Chlorobaculum tepidum. PHOTOSYNTHESIS RESEARCH 2009; 101:21-34. [PMID: 19568953 DOI: 10.1007/s11120-009-9460-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2009] [Accepted: 06/10/2009] [Indexed: 05/28/2023]
Abstract
The first committed step in the biosynthesis of (bacterio-)chlorophyll is the insertion of Mg2+ into protoporphyrin IX by Mg-chelatase. In all known (B)Chl-synthesizing organisms, Mg-chelatase is encoded by three genes that are homologous to bchH, bchD, and bchI of Rhodobacter spp. The genomes of all sequenced strains of green sulfur bacteria (Chlorobi) encode multiple bchH paralogs, and in the genome of Chlorobaculum tepidum, there are three bchH paralogs, denoted CT1295 (bchT), CT1955 (bchS), and CT1957 (bchH). Cba. tepidum mutants lacking one or two of these paralogs were constructed and characterized. All of the mutants lacking only one of these BchH homologs, as well as bchS bchT and bchH bchT double mutants, which can only produce BchH or BchS, respectively, were viable. However, attempts to construct a bchH bchS double mutant, in which only BchT was functional, were consistently unsuccessful. This result suggested that BchT alone is unable to support the minimal (B)Chl synthesis requirements of cells required for viability. The pigment compositions of the various mutant strains varied significantly. The BChl c content of the bchS mutant was only approximately 10% of that of the wild type, and this mutant excreted large amounts of protoporphyrin IX into the growth medium. The observed differences in BChl c production of the mutant strains were consistent with the hypothesis that the three BchH homologs function in end product regulation and/or substrate channeling of intermediates in the BChl c biosynthetic pathway.
Collapse
Affiliation(s)
- Aline Gomez Maqueo Chew
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, S-235 Frear Building, PA 16802, University Park, USA
| | | | | |
Collapse
|
16
|
Johnson ET, Schmidt-Dannert C. Light-energy conversion in engineered microorganisms. Trends Biotechnol 2008; 26:682-9. [PMID: 18951642 DOI: 10.1016/j.tibtech.2008.09.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 09/05/2008] [Accepted: 09/11/2008] [Indexed: 11/19/2022]
Abstract
Increasing interest in renewable resources by the energy and chemical industries has spurred new technologies both to capture solar energy and to develop biologically derived chemical feedstocks and fuels. Advances in molecular biology and metabolic engineering have provided new insights and techniques for increasing biomass and biohydrogen production, and recent efforts in synthetic biology have demonstrated that complex regulatory and metabolic networks can be designed and engineered in microorganisms. Here, we explore how light-driven processes may be incorporated into nonphotosynthetic microbes to boost metabolic capacity for the production of industrial and fine chemicals. Progress towards the introduction of light-driven proton pumping or anoxygenic photosynthesis into Escherichia coli to increase the efficiency of metabolically-engineered biosynthetic pathways is highlighted.
Collapse
Affiliation(s)
- Ethan T Johnson
- Department of Biochemistry, Molecular Biology and Biophysics, 1479 Gortner Avenue, 140 Gortner Laboratory, University of Minnesota, St. Paul, MN 55108, USA
| | | |
Collapse
|