1
|
Campbell IJ, Kahanda D, Atkinson JT, Sparks ON, Kim J, Tseng CP, Verduzco R, Bennett GN, Silberg JJ. Recombination of 2Fe-2S Ferredoxins Reveals Differences in the Inheritance of Thermostability and Midpoint Potential. ACS Synth Biol 2020; 9:3245-3253. [PMID: 33226772 DOI: 10.1021/acssynbio.0c00303] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Recombination can be used in the laboratory to overcome component limitations in synthetic biology by creating enzymes that exhibit distinct activities and stabilities from native proteins. To investigate how recombination affects the properties of an oxidoreductase that transfers electrons in cells, we created ferredoxin (Fd) chimeras by recombining distantly related cyanobacterial and cyanomyophage Fds (53% identity) that present similar midpoint potentials but distinct thermostabilities. Fd chimeras having a wide range of amino acid substitutions retained the ability to coordinate an iron-sulfur cluster, although their thermostabilities varied with the fraction of residues inherited from each parent. The midpoint potentials of chimeric Fds also varied. However, all of the synthetic Fds exhibited midpoint potentials outside of the parental protein range. Each of the chimeric Fds could also support electron transfer between Fd-NADP reductase and sulfite reductase in Escherichia coli, although the chimeric Fds varied in the expression required for similar levels of cellular electron transfer. These results show how Fds can be diversified through recombination and reveal differences in the inheritance of thermostability and electrochemical properties. Furthermore, they illustrate how electron transfer efficiencies of chimeric Fds can be rapidly evaluated using a synthetic metabolic pathway.
Collapse
Affiliation(s)
- Ian J. Campbell
- Department of BioSciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Dimithree Kahanda
- Department of BioSciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Joshua T. Atkinson
- Department of BioSciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Othneil Noble Sparks
- Department of BioSciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Jinyoung Kim
- Department of BioSciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
| | - Chia-Ping Tseng
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, Texas 77005, United States
| | - Rafael Verduzco
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, Texas 77005, United States
| | - George N. Bennett
- Department of BioSciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, Texas 77005, United States
| | - Jonathan J. Silberg
- Department of BioSciences, Rice University, 6100 Main Street, MS-140, Houston, Texas 77005, United States
- Department of Chemical and Biomolecular Engineering, Rice University, 6100 Main Street, MS-362, Houston, Texas 77005, United States
- Department of Bioengineering, Rice University, 6100 Main Street, MS-142, Houston, Texas 77005, United States
| |
Collapse
|
2
|
Campbell IJ, Olmos JL, Xu W, Kahanda D, Atkinson JT, Sparks ON, Miller MD, Phillips GN, Bennett GN, Silberg JJ. Prochlorococcus phage ferredoxin: structural characterization and electron transfer to cyanobacterial sulfite reductases. J Biol Chem 2020; 295:10610-10623. [PMID: 32434930 DOI: 10.1074/jbc.ra120.013501] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 05/15/2020] [Indexed: 01/13/2023] Open
Abstract
Marine cyanobacteria are infected by phages whose genomes encode ferredoxin (Fd) electron carriers. These Fds are thought to redirect the energy harvested from light to phage-encoded oxidoreductases that enhance viral fitness, but it is unclear how the biophysical properties and partner specificities of phage Fds relate to those of photosynthetic organisms. Here, results of a bioinformatics analysis using a sequence similarity network revealed that phage Fds are most closely related to cyanobacterial Fds that transfer electrons from photosystems to oxidoreductases involved in nutrient assimilation. Structural analysis of myovirus P-SSM2 Fd (pssm2-Fd), which infects the cyanobacterium Prochlorococcus marinus, revealed high levels of similarity to cyanobacterial Fds (root mean square deviations of ≤0.5 Å). Additionally, pssm2-Fd exhibited a low midpoint reduction potential (-336 mV versus a standard hydrogen electrode), similar to other photosynthetic Fds, although it had lower thermostability (Tm = 28 °C) than did many other Fds. When expressed in an Escherichia coli strain deficient in sulfite assimilation, pssm2-Fd complemented bacterial growth when coexpressed with a P. marinus sulfite reductase, revealing that pssm2-Fd can transfer electrons to a host protein involved in nutrient assimilation. The high levels of structural similarity with cyanobacterial Fds and reactivity with a host sulfite reductase suggest that phage Fds evolved to transfer electrons to cyanobacterially encoded oxidoreductases.
Collapse
Affiliation(s)
- Ian J Campbell
- Biochemistry and Cell Biology Graduate Program, Rice University, Houston, Texas, USA.,Department of Biosciences, Rice University, Houston, Texas, USA
| | - Jose Luis Olmos
- Biochemistry and Cell Biology Graduate Program, Rice University, Houston, Texas, USA.,Department of Biosciences, Rice University, Houston, Texas, USA
| | - Weijun Xu
- Department of Biosciences, Rice University, Houston, Texas, USA
| | | | | | | | | | - George N Phillips
- Department of Biosciences, Rice University, Houston, Texas, USA.,Department of Chemistry, Rice University, Houston, Texas, USA
| | - George N Bennett
- Department of Biosciences, Rice University, Houston, Texas, USA.,Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA
| | - Jonathan J Silberg
- Department of Biosciences, Rice University, Houston, Texas, USA .,Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA.,Department of Bioengineering, Rice University, Houston, Texas, USA
| |
Collapse
|
3
|
Jez JM. Structural biology of plant sulfur metabolism: from sulfate to glutathione. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:4089-4103. [PMID: 30825314 DOI: 10.1093/jxb/erz094] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 02/12/2019] [Indexed: 06/09/2023]
Abstract
Sulfur is an essential element for all organisms. Plants must assimilate this nutrient from the environment and convert it into metabolically useful forms for the biosynthesis of a wide range of compounds, including cysteine and glutathione. This review summarizes structural biology studies on the enzymes involved in plant sulfur assimilation [ATP sulfurylase, adenosine-5'-phosphate (APS) reductase, and sulfite reductase], cysteine biosynthesis (serine acetyltransferase and O-acetylserine sulfhydrylase), and glutathione biosynthesis (glutamate-cysteine ligase and glutathione synthetase) pathways. Overall, X-ray crystal structures of enzymes in these core pathways provide molecular-level information on the chemical events that allow plants to incorporate sulfur into essential metabolites and revealed new biochemical regulatory mechanisms, such as structural rearrangements, protein-protein interactions, and thiol-based redox switches, for controlling different steps in these pathways.
Collapse
Affiliation(s)
- Joseph M Jez
- Department of Biology, Washington University in St. Louis, St. Louis, MO, USA
| |
Collapse
|
4
|
Atkinson JT, Campbell IJ, Thomas EE, Bonitatibus SC, Elliott SJ, Bennett GN, Silberg JJ. Metalloprotein switches that display chemical-dependent electron transfer in cells. Nat Chem Biol 2018; 15:189-195. [PMID: 30559426 DOI: 10.1038/s41589-018-0192-3] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/07/2018] [Indexed: 11/09/2022]
Abstract
Biological electron transfer is challenging to directly regulate using environmental conditions. To enable dynamic, protein-level control over energy flow in metabolic systems for synthetic biology and bioelectronics, we created ferredoxin logic gates that utilize transcriptional and post-translational inputs to control energy flow through a synthetic electron transfer pathway that is required for bacterial growth. These logic gates were created by subjecting a thermostable, plant-type ferredoxin to backbone fission and fusing the resulting fragments to a pair of proteins that self-associate, a pair of proteins whose association is stabilized by a small molecule, and to the termini of a ligand-binding domain. We show that the latter domain insertion design strategy yields an allosteric ferredoxin switch that acquires an oxygen-tolerant [2Fe-2S] cluster and can use different chemicals, including a therapeutic drug and an environmental pollutant, to control the production of a reduced metabolite in Escherichia coli and cell lysates.
Collapse
Affiliation(s)
- Joshua T Atkinson
- Systems, Synthetic, and Physical Biology Graduate Program, Rice University, Houston, TX, USA
| | - Ian J Campbell
- Biochemistry and Cell Biology Graduate Program, Rice University, Houston, TX, USA
| | - Emily E Thomas
- Biochemistry and Cell Biology Graduate Program, Rice University, Houston, TX, USA
| | | | - Sean J Elliott
- Department of Chemistry, Boston University, Boston, MA, USA
| | - George N Bennett
- Department of BioSciences, Rice University, Houston, TX, USA.,Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX, USA
| | - Jonathan J Silberg
- Department of BioSciences, Rice University, Houston, TX, USA. .,Department of Bioengineering, Rice University, Houston, TX, USA.
| |
Collapse
|
5
|
Walters KA, Golbeck JH. Expression, purification and characterization of an active C491G variant of ferredoxin sulfite reductase from Synechococcus elongatus PCC 7942. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2018; 1859:1096-1107. [PMID: 29959913 DOI: 10.1016/j.bbabio.2018.06.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 06/22/2018] [Accepted: 06/26/2018] [Indexed: 10/28/2022]
Abstract
Recently developed molecular wire technology takes advantage of [4Fe-4S] clusters that are ligated by at least one surface exposed Cys residue. Mutagenesis of this Cys residue to a Gly opens an exchangeable coordination site to a corner iron atom that can be chemically rescued by an external thiolate ligand. This ligand can be subsequently displaced by mass action using a dithiol molecular wire to tether two redox active proteins. We intend to apply this technique to tethering Photosystem I to ferredoxin sulfite reductase (FdSiR), an enzyme that catalyzes the six-electron reduction of sulfite to hydrogen sulfite and nitrite to ammonia. The enzyme contains a [4Fe-4S]2+/1+ cluster and a siroheme active site. FdSiRWT and an FdSiRC491G variant were cloned from Synechococcus elongatus PCC 7942 and expressed along with the cysG gene from Salmonella typhimurium using the pCDFDuet plasmid. UV/Vis absorbance spectra of both FdSiRWT and the FdSiRC491G variant displayed characteristic peaks at 278, 392 (Soret), 585 (α) and 714 nm (charge transfer band), and 278, 394 (Soret), 587 (α) and 714 nm (charge transfer band) respectively. Both enzymes in their as-isolated forms displayed an EPR spectrum characteristic of an S = 5/2 high spin heme. When reduced, both enzymes exhibited the signal of a low spin S = 1/2 [4Fe-4S]1+ cluster. The FdSiRWT and FdSiRC491G variant both showed activity using reduced methyl viologen and Synechococcus elongatus PCC 7942 ferredoxin 1 (Fd1) as electron donors. Based on these results, the FdSIRC491G variant should be a suitable candidate for wiring to Photosystem I.
Collapse
Affiliation(s)
- Karim A Walters
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States
| | - John H Golbeck
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States; Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, United States.
| |
Collapse
|
6
|
Guan X, Chen S, Voon CP, Wong KB, Tikkanen M, Lim BL. FdC1 and Leaf-Type Ferredoxins Channel Electrons From Photosystem I to Different Downstream Electron Acceptors. FRONTIERS IN PLANT SCIENCE 2018; 9:410. [PMID: 29670639 PMCID: PMC5893904 DOI: 10.3389/fpls.2018.00410] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 03/14/2018] [Indexed: 05/24/2023]
Abstract
Plant-type ferredoxins in Arabidopsis transfer electrons from the photosystem I to multiple redox-driven enzymes involved in the assimilation of carbon, nitrogen, and sulfur. Leaf-type ferredoxins also modulate the switch between the linear and cyclic electron routes of the photosystems. Recently, two novel ferredoxin homologs with extra C-termini were identified in the Arabidopsis genome (AtFdC1, AT4G14890; AtFdC2, AT1G32550). FdC1 was considered as an alternative electron acceptor of PSI under extreme ferredoxin-deficient conditions. Here, we showed that FdC1 could interact with some, but not all, electron acceptors of leaf-type Fds, including the ferredoxin-thioredoxin reductase (FTR), sulfite reductase (SiR), and nitrite reductase (NiR). Photoreduction assay on cytochrome c and enzyme assays confirmed its capability to receive electrons from PSI and donate electrons to the Fd-dependent SiR and NiR but not to the ferredoxin-NADP+ oxidoreductase (FNR). Hence, FdC1 and leaf-type Fds may play differential roles by channeling electrons from photosystem I to different downstream electron acceptors in photosynthetic tissues. In addition, the median redox potential of FdC1 may allow it to receive electrons from FNR in non-photosynthetic plastids.
Collapse
Affiliation(s)
- Xiaoqian Guan
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Shuai Chen
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Chia Pao Voon
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kam-Bo Wong
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Mikko Tikkanen
- Department of Biochemistry and Food Chemistry, Molecular Plant Biology, University of Turku, Turku, Finland
| | - Boon L. Lim
- School of Biological Sciences, The University of Hong Kong, Pokfulam, Hong Kong
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Shatin, Hong Kong
| |
Collapse
|
7
|
Structure and electrochemistry of proteins harboring iron-sulfur clusters of different nuclearities. Part I. [4Fe-4S] + [2Fe-2S] iron-sulfur proteins. J Struct Biol 2017; 200:1-19. [DOI: 10.1016/j.jsb.2017.05.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 05/25/2017] [Indexed: 01/08/2023]
|
8
|
Zanello P. The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part V. {[Fe4S4](SCysγ)4} proteins. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2016.10.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
|
9
|
Kim JY, Nakayama M, Toyota H, Kurisu G, Hase T. Structural and mutational studies of an electron transfer complex of maize sulfite reductase and ferredoxin. J Biochem 2016; 160:101-9. [DOI: 10.1093/jb/mvw016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 02/01/2016] [Indexed: 11/14/2022] Open
|
10
|
Liu J, Chakraborty S, Hosseinzadeh P, Yu Y, Tian S, Petrik I, Bhagi A, Lu Y. Metalloproteins containing cytochrome, iron-sulfur, or copper redox centers. Chem Rev 2014; 114:4366-469. [PMID: 24758379 PMCID: PMC4002152 DOI: 10.1021/cr400479b] [Citation(s) in RCA: 560] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Indexed: 02/07/2023]
Affiliation(s)
- Jing Liu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Saumen Chakraborty
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Parisa Hosseinzadeh
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yang Yu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shiliang Tian
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Igor Petrik
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry, Department of Biochemistry, and Center for Biophysics
and Computational
Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| |
Collapse
|
11
|
Hanke G, Mulo P. Plant type ferredoxins and ferredoxin-dependent metabolism. PLANT, CELL & ENVIRONMENT 2013; 36:1071-1084. [PMID: 23190083 DOI: 10.1111/pce.12046] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 11/19/2012] [Accepted: 11/20/2012] [Indexed: 05/24/2023]
Abstract
Ferredoxin (Fd) is a small [2Fe-2S] cluster-containing protein found in all organisms performing oxygenic photosynthesis. Fd is the first soluble acceptor of electrons on the stromal side of the chloroplast electron transport chain, and as such is pivotal to determining the distribution of these electrons to different metabolic reactions. In chloroplasts, the principle sink for electrons is in the production of NADPH, which is mostly consumed during the assimilation of CO2 . In addition to this primary function in photosynthesis, Fds are also involved in a number of other essential metabolic reactions, including biosynthesis of chlorophyll, phytochrome and fatty acids, several steps in the assimilation of sulphur and nitrogen, as well as redox signalling and maintenance of redox balance via the thioredoxin system and Halliwell-Asada cycle. This makes Fds crucial determinants of the electron transfer between the thylakoid membrane and a variety of soluble enzymes dependent on these electrons. In this article, we will first describe the current knowledge on the structure and function of the various Fd isoforms present in chloroplasts of higher plants and then discuss the processes involved in oxidation of Fd, introducing the corresponding enzymes and discussing what is known about their relative interaction with Fd.
Collapse
Affiliation(s)
- Guy Hanke
- Plant Physiology, Faculty of Biology and Chemistry, University of Osnabrück, DE-49076, Osnabrück, Germany
| | | |
Collapse
|
12
|
Sakakibara Y, Kimura H, Iwamura A, Saitoh T, Ikegami T, Kurisu G, Hase T. A new structural insight into differential interaction of cyanobacterial and plant ferredoxins with nitrite reductase as revealed by NMR and X-ray crystallographic studies. J Biochem 2012; 151:483-92. [PMID: 22427434 DOI: 10.1093/jb/mvs028] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ferredoxin (Fd), which plays a pivotal role in photosynthesis as an electron carrier, forms a transient complex with various Fd-dependent enzymes, such as nitrite reductase (NiR), to achieve efficient intermolecular electron transfer. We studied the protein-protein interaction of Fd and NiR by NMR spectroscopy and determined three acidic regions of Fd to be major sites for the interaction with NiR, indicating that the complex is stabilized through electrostatic interaction. During this study, we found Fds from higher plant and cyanobacterium, in spite of their high structural similarities including the above acidic regions, differ remarkably in the interaction with cyanobacterial NiR. In activity assay of NiR, K(m) value for maize Fd (74.6 µM) was 9.6 times larger than that for Leptolyngbya boryana Fd (7.8 µM). The two Fds also showed a similar difference in binding assay to NiR-immobilized resin. Comparative site-specific mutagenesis of two Fds revealed that their discriminative ability for the interaction with NiR is attributed mainly to non-charged residues in the peripheral region of [2Fe-2S] cluster. These non-charged residues are conserved separately between Fds of plant and cyanobacterial origins. Our data highlight that intermolecular force(s) other than electrostatic attraction is(are) also crucial for the molecular interaction between Fd and partner enzyme.
Collapse
Affiliation(s)
- Yukiko Sakakibara
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | | | | | | | | | | | | |
Collapse
|
13
|
Eichelmann H, Oja V, Peterson R, Laisk A. The rate of nitrite reduction in leaves as indicated by O₂ and CO₂ exchange during photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:2205-15. [PMID: 21239375 PMCID: PMC3060700 DOI: 10.1093/jxb/erq428] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Light response (at 300 ppm CO(2) and 10-50 ppm O(2) in N(2)) and CO(2) response curves [at absorbed photon fluence rate (PAD) of 550 μmol m(-2) s(-1)] of O(2) evolution and CO(2) uptake were measured in tobacco (Nicotiana tabacum L.) leaves grown on either NO(3)(-) or NH(4)(+) as N source and in potato (Solanum tuberosum L.), sorghum (Sorghum bicolor L. Moench), and amaranth (Amaranthus cruentus L.) leaves grown on NH(4)NO(3). Photosynthetic O(2) evolution in excess of CO(2) uptake was measured with a stabilized zirconia O(2) electrode and an infrared CO(2) analyser, respectively, and the difference assumed to represent the rate of electron flow to acceptors alternative to CO(2), mainly NO(2)(-), SO(4)(2-), and oxaloacetate. In NO(3)(-)-grown tobacco, as well as in sorghum, amaranth, and young potato, the photosynthetic O(2)-CO(2) flux difference rapidly increased to about 1 μmol m(-2) s(-1) at very low PADs and the process was saturated at 50 μmol quanta m(-2) s(-1). At higher PADs the O(2)-CO(2) flux difference continued to increase proportionally with the photosynthetic rate to a maximum of about 2 μmol m(-2) s(-1). In NH(4)(+)-grown tobacco, as well as in potato during tuber filling, the low-PAD component of surplus O(2) evolution was virtually absent. The low-PAD phase was ascribed to photoreduction of NO(2)(-) which successfully competes with CO(2) reduction and saturates at a rate of about 1 μmol O(2) m(-2) s(-1) (9% of the maximum O(2) evolution rate). The high-PAD component of about 1 μmol O(2) m(-2) s(-1), superimposed on NO(2)(-) reduction, may represent oxaloacetate reduction. The roles of NO(2)(-), oxaloacetate, and O(2) reduction in the regulation of ATP/NADPH balance are discussed.
Collapse
Affiliation(s)
- H. Eichelmann
- Institute of Molecular and Cell Biology, Tartu University, Riia st. 23, Tartu 51010, Estonia
| | - V. Oja
- Institute of Molecular and Cell Biology, Tartu University, Riia st. 23, Tartu 51010, Estonia
| | - R.B. Peterson
- Department of Biochemistry and Genetics, The Connecticut Agricultural Experiment Station, 123 Huntington St., New Haven, CT 06511, USA
| | - A. Laisk
- Institute of Molecular and Cell Biology, Tartu University, Riia st. 23, Tartu 51010, Estonia
- To whom correspondence should be addressed: E-mail:
| |
Collapse
|
14
|
Yi H, Ravilious GE, Galant A, Krishnan HB, Jez JM. From sulfur to homoglutathione: thiol metabolism in soybean. Amino Acids 2010; 39:963-78. [PMID: 20364282 DOI: 10.1007/s00726-010-0572-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2009] [Accepted: 03/16/2010] [Indexed: 12/11/2022]
Abstract
Sulfur is an essential plant nutrient and is metabolized into the sulfur-containing amino acids (cysteine and methionine) and into molecules that protect plants against oxidative and environmental stresses. Although studies of thiol metabolism in the model plant Arabidopsis thaliana (thale cress) have expanded our understanding of these dynamic processes, our knowledge of how sulfur is assimilated and metabolized in crop plants, such as soybean (Glycine max), remains limited in comparison. Soybean is a major crop used worldwide for food and animal feed. Although soybeans are protein-rich, they do not contain high levels of the sulfur-containing amino acids, cysteine and methionine. Ultimately, unraveling the fundamental steps and regulation of thiol metabolism in soybean is important for optimizing crop yield and quality. Here we review the pathways from sulfur uptake to glutathione and homoglutathione synthesis in soybean, the potential biotechnology benefits of understanding and modifying these pathways, and how information from the soybean genome may guide the next steps in exploring this biochemical system.
Collapse
Affiliation(s)
- Hankuil Yi
- Department of Biology, Washington University, St. Louis, MO 63130, USA
| | | | | | | | | |
Collapse
|
15
|
Imamura S, Terashita M, Ohnuma M, Maruyama S, Minoda A, Weber APM, Inouye T, Sekine Y, Fujita Y, Omata T, Tanaka K. Nitrate assimilatory genes and their transcriptional regulation in a unicellular red alga Cyanidioschyzon merolae: genetic evidence for nitrite reduction by a sulfite reductase-like enzyme. PLANT & CELL PHYSIOLOGY 2010; 51:707-17. [PMID: 20375110 DOI: 10.1093/pcp/pcq043] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Cyanidioschyzon merolae is a unicellular red alga living in acid hot springs, which is able to grow on ammonium, as well as nitrate as sole nitrogen source. Based on the complete genome sequence, proteins for nitrate utilization, nitrate transporter (NRT) and nitrate reductase (NR), were predicted to be encoded by the neighboring nuclear genes CMG018C and CMG019C, respectively, but no typical nitrite reductase (NiR) gene was found by similarity searches. On the other hand, two candidate genes for sulfite reductase (SiR) were found, one of which (CMG021C) is located next to the above-noted nitrate-related genes. Given that transcripts of CMG018C, CMG019C and CMG021C accumulate in nitrate-containing media, but are repressed by ammonium, and that SiR and NiR are structurally related enzymes, we hypothesized that the CMG021C gene product functions as an NiR in C. merolae. To test this hypothesis, we developed a method for targeted gene disruption in C. merolae. In support of our hypothesis, we found that a CMG021G null mutant in comparison with the parental strain showed decreased cell growth in nitrate-containing but not in ammonium-containing media. Furthermore, expression of CMG021C in the nirA mutant of a cyanobacterium, Leptolyngbya boryana (formerly Plectonema boryanum), could genetically complement the NiR defect. Immunofluorescent analysis indicated the localization of CMG021C in chloroplasts, and hence we propose an overall scheme for nitrate assimilation in C. merolae.
Collapse
Affiliation(s)
- Sousuke Imamura
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Saitoh T, Ikegami T, Nakayama M, Teshima K, Akutsu H, Hase T. NMR study of the electron transfer complex of plant ferredoxin and sulfite reductase: mapping the interaction sites of ferredoxin. J Biol Chem 2006; 281:10482-8. [PMID: 16469743 DOI: 10.1074/jbc.m510530200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Plant ferredoxin serves as the physiological electron donor for sulfite reductase, which catalyzes the reduction of sulfite to sulfide. Ferredoxin and sulfite reductase form an electrostatically stabilized 1:1 complex for the intermolecular electron transfer. The protein-protein interaction between these proteins from maize leaves was analyzed by nuclear magnetic resonance spectroscopy. Chemical shift perturbation and cross-saturation experiments successfully mapped the location of two major interaction sites of ferredoxin: region 1 including Glu-29, Glu-30, and Asp-34 and region 2 including Glu-92, Glu-93, and Glu-94. The importance of these two acidic patches for interaction with sulfite reductase was confirmed by site-specific mutation of acidic ferredoxin residues in regions 1 and 2, separately and in combination, by which the ability of mutant ferredoxins to transfer electrons and bind to sulfite reductase was additively lowered. Taken together, this study gives a clear illustration of the molecular interaction between ferredoxin and sulfite reductase. We also present data showing that this interaction surface of ferredoxin significantly differs from that when ferredoxin-NADP(+) reductase is the interaction partner.
Collapse
Affiliation(s)
- Takashi Saitoh
- Institute for Protein Research, Osaka University, 3-2, Yamadaoka, Suita, Osaka 565-0871, Japan
| | | | | | | | | | | |
Collapse
|
17
|
Hirasawa M, Nakayama M, Kim SK, Hase T, Knaff DB. Chemical modification studies of tryptophan, arginine and lysine residues in maize chloroplast ferredoxin:sulfite oxidoreductase. PHOTOSYNTHESIS RESEARCH 2005; 86:325-36. [PMID: 16307304 DOI: 10.1007/s11120-005-6966-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Accepted: 05/04/2005] [Indexed: 05/05/2023]
Abstract
The ferredoxin-dependent sulfite reductase from maize was treated, in separate experiments, with three different covalent modifiers of specific amino acid side chains. Treatment with the tryptophan-modifying reagent, N-bromosuccinimide (NBS), resulted in a loss of enzymatic activity with both the physiological donor for the enzyme, reduced ferredoxin, and with reduced methyl viologen, a non-physiological electron donor. Formation of the 1:1 ferredoxin/sulfite reductase complex prior to treating the enzyme with NBS completely protected the enzyme against the loss of both activities. Neither the secondary structure, nor the oxidation-reduction midpoint potential (Em) values of the siroheme and [4Fe-4S] cluster prosthetic groups of sulfite reductase, nor the binding affinity of the enzyme for ferredoxin were affected by NBS treatment. Treatment of sulfite reductase with the lysine-modifying reagent, N-acetylsuccinimide, inhibited the ferredoxin-linked activity of the enzyme without inhibiting the methyl viologen-linked activity. Complex formation with ferredoxin protects the enzyme against the inhibition of ferredoxin-linked activity produced by treatment with N-acetylsuccinimide. Treatment of sulfite reductase with N-acetylsuccinimide also decreased the binding affinity of the enzyme for ferredoxin. Treatment of sulfite reductase with the arginine-modifying reagent, phenylglyoxal, inhibited both the ferredoxin-linked and methyl viologen-linked activities of the enzyme but had a significantly greater effect on the ferredoxin-dependent activity than on the reduced methyl viologen-linked activity. The effects of these three inhibitory treatments are consistent with a possible role for a tryptophan residue the catalytic mechanism of sulfite reductase and for lysine and arginine residues at the ferredoxin-binding site of the enzyme.
Collapse
Affiliation(s)
- Masakazu Hirasawa
- Department of Chemistry and Biochemistry and Center for Biotechnology and Genomics, Texas Tech University, Lubbock, TX 79409-1061, USA
| | | | | | | | | |
Collapse
|