1
|
Sha C, Wang Q, Wang H, Duan Y, Xu C, Wu L, Ma K, Shao W, Jiang Y. Characterization of Thermotoga neapolitana Alcohol Dehydrogenases in the Ethanol Fermentation Pathway. BIOLOGY 2022; 11:biology11091318. [PMID: 36138797 PMCID: PMC9495900 DOI: 10.3390/biology11091318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/26/2022] [Accepted: 09/01/2022] [Indexed: 11/16/2022]
Abstract
Hyperthermophilic Thermotoga spp. are candidates for cellulosic ethanol fermentation. A bifunctional iron-acetaldehyde/alcohol dehydrogenase (Fe-AAdh) has been revealed to catalyze the acetyl-CoA (Ac-CoA) reduction to form ethanol via an acetaldehyde intermediate in Thermotoga neapolitana (T. neapolitana). In this organism, there are three additional alcohol dehydrogenases, Zn-Adh, Fe-Adh1, and Fe-Adh2, encoded by genes CTN_0257, CTN_1655, and CTN_1756, respectively. This paper reports the properties and functions of these enzymes in the fermentation pathway from Ac-CoA to ethanol. It was determined that Zn-Adh only exhibited activity when oxidizing ethanol to acetaldehyde, and no detectable activity for the reaction from acetaldehyde to ethanol. Fe-Adh1 had specific activities of approximately 0.7 and 0.4 U/mg for the forward and reverse reactions between acetaldehyde and ethanol at a pHopt of 8.5 and Topt of 95 °C. Catalyzing the reduction of acetaldehyde to produce ethanol, Fe-Adh2 exhibited the highest activity of approximately 3 U/mg at a pHopt of 7.0 and Topt of 85 °C, which were close to the optimal growth conditions. These results indicate that Fe-Adh2 and Zn-Adh are the main enzymes that catalyze ethanol formation and consumption in the hyperthermophilic bacterium, respectively.
Collapse
Affiliation(s)
- Chong Sha
- Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013, China
| | - Qiang Wang
- Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013, China
- School of Biological and Food Engineering, Suzhou University, Bianhe Middle Road 49, Suzhou 234000, China
| | - Hongcheng Wang
- Biofuels Institute, School of the Environment, Jiangsu University, Zhenjiang 212013, China
| | - Yilan Duan
- School of Biological and Food Engineering, Suzhou University, Bianhe Middle Road 49, Suzhou 234000, China
| | - Chongmao Xu
- Huzhou Research Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou 313000, China
| | - Lian Wu
- Huzhou Research Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou 313000, China
| | - Kesen Ma
- Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada
| | - Weilan Shao
- Shine E BioTech (Nanjing) Company, Nanjing 210023, China
- Correspondence: (W.S.); (Y.J.)
| | - Yu Jiang
- Huzhou Research Center of Industrial Biotechnology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Huzhou 313000, China
- Correspondence: (W.S.); (Y.J.)
| |
Collapse
|
2
|
Thermostable and O2-Insensitive Pyruvate Decarboxylases from Thermoacidophilic Archaea Catalyzing the Production of Acetaldehyde. BIOLOGY 2022; 11:biology11081247. [PMID: 36009875 PMCID: PMC9405506 DOI: 10.3390/biology11081247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 08/03/2022] [Accepted: 08/16/2022] [Indexed: 11/16/2022]
Abstract
Simple Summary Pyruvate decarboxylase (PDC) is a key enzyme involved in ethanol fermentation, a process for the production of biofuels. Thermostable and oxygen-stable PDC activity is highly desirable for biotechnological applications at high temperatures. The enzymes from the thermoacidophiles Saccharolobus (formerly Sulfolobus) solfataricus (Ss, Topt = 80 °C) and Sulfolobus acidocaldarius (Sa, Topt = 80 °C) were purified and characterized, and their biophysical and biochemical properties were determined comparatively. The purified enzymes were CoA-dependent and thermostable. There was no loss of activity in the presence of oxygen. In conclusion, both thermostable SsPDC and SaPDC catalyze the CoA-dependent production of acetaldehyde from pyruvate in the presence of oxygen. Abstract Pyruvate decarboxylase (PDC) is a key enzyme involved in ethanol fermentation, and it catalyzes the decarboxylation of pyruvate to acetaldehyde and CO2. Bifunctional PORs/PDCs that also have additional pyruvate:ferredoxin oxidoreductase (POR) activity are found in hyperthermophiles, and they are mostly oxygen-sensitive and CoA-dependent. Thermostable and oxygen-stable PDC activity is highly desirable for biotechnological applications. The enzymes from the thermoacidophiles Saccharolobus (formerly Sulfolobus) solfataricus (Ss, Topt = 80 °C) and Sulfolobus acidocaldarius (Sa, Topt = 80 °C) were purified and characterized, and their biophysical and biochemical properties were determined comparatively. Both enzymes were shown to be heterodimeric, and their two subunits were determined by SDS-PAGE to be 37 ± 3 kDa and 65 ± 2 kDa, respectively. The purified enzymes from S. solfataricus and S. acidocaldarius showed both PDC and POR activities which were CoA-dependent, and they were thermostable with half-life times of 2.9 ± 1 and 1.1 ± 1 h at 80 °C, respectively. There was no loss of activity in the presence of oxygen. Optimal pH values for their PDC and POR activity were determined to be 7.9 and 8.6, respectively. In conclusion, both thermostable SsPOR/PDC and SaPOR/PDC catalyze the CoA-dependent production of acetaldehyde from pyruvate in the presence of oxygen.
Collapse
|
3
|
Abstract
DPANN is known as highly diverse, globally widespread, and mostly ectosymbiotic archaeal superphylum. However, this group of archaea was overlooked for a long time, and there were limited in-depth studies reported. In this investigation, 41 metagenome-assembled genomes (MAGs) belonging to the DPANN superphylum were recovered (18 MAGs had average nucleotide identity [ANI] values of <95% and a percentage of conserved proteins [POCP] of >50%, while 14 MAGs showed a POCP of <50%), which were analyzed comparatively with 515 other published DPANN genomes. Mismatches to known 16S rRNA gene primers were identified among 16S rRNA genes of DPANN archaea. Numbers of gene families lost (mostly related to energy and amino acid metabolism) were over three times greater than those gained in the evolution of DPANN archaea. Lateral gene transfer (LGT; ∼45.5% was cross-domain) had facilitated niche adaption of the DPANN archaea, ensuring a delicate equilibrium of streamlined genomes with efficient niche-adaptive strategies. For instance, LGT-derived cytochrome bd ubiquinol oxidase and arginine deiminase in the genomes of “Candidatus Micrarchaeota” could help them better adapt to aerobic acidic mine drainage habitats. In addition, most DPANN archaea acquired enzymes for biosynthesis of extracellular polymeric substances (EPS) and transketolase/transaldolase for the pentose phosphate pathway from Bacteria. IMPORTANCE The domain Archaea is a key research model for gaining insights into the origin and evolution of life, as well as the relevant biogeochemical processes. The discovery of nanosized DPANN archaea has overthrown many aspects of microbiology. However, the DPANN superphylum still contains a vast genetic novelty and diversity that need to be explored. Comprehensively comparative genomic analysis on the DPANN superphylum was performed in this study, with an attempt to illuminate its metabolic potential, ecological distribution and evolutionary history. Many interphylum differences within the DPANN superphylum were found. For example, Altiarchaeota had the biggest genome among DPANN phyla, possessing many pathways missing in other phyla, such as formaldehyde assimilation and the Wood-Ljungdahl pathway. In addition, LGT acted as an important force to provide DPANN archaeal genetic flexibility that permitted the occupation of diverse niches. This study has advanced our understanding of the diversity and genome evolution of archaea.
Collapse
|
4
|
Mazeed M, Singh R, Kumar P, Roy A, Raman B, Kruparani SP, Sankaranarayanan R. Recruitment of archaeal DTD is a key event toward the emergence of land plants. SCIENCE ADVANCES 2021; 7:7/6/eabe8890. [PMID: 33536220 PMCID: PMC7857688 DOI: 10.1126/sciadv.abe8890] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/16/2020] [Indexed: 06/09/2023]
Abstract
Streptophyte algae emerged as a land plant with adaptations that eventually led to terrestrialization. Land plants encounter a range of biotic and abiotic stresses that elicit anaerobic stress responses. Here, we show that acetaldehyde, a toxic metabolite of anaerobic stress, targets and generates ethyl adducts on aminoacyl-tRNA, a central component of the translation machinery. However, elongation factor thermo unstable (EF-Tu) safeguards l-aminoacyl-tRNA, but not d-aminoacyl-tRNA, from being modified by acetaldehyde. We identified a unique activity of archaeal-derived chiral proofreading module, d-aminoacyl-tRNA deacylase 2 (DTD2), that removes N-ethyl adducts formed on d-aminoacyl-tRNAs (NEDATs). Thus, the study provides the molecular basis of ethanol and acetaldehyde hypersensitivity in DTD2 knockout plants. We uncovered an important gene transfer event from methanogenic archaea to the ancestor of land plants. While missing in other algal lineages, DTD2 is conserved from streptophyte algae to land plants, suggesting its role toward the emergence and evolution of land plants.
Collapse
Affiliation(s)
- Mohd Mazeed
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
| | - Raghvendra Singh
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
| | - Pradeep Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
- Academy of Scientific and Innovative Research (AcSIR), CSIR-CCMB campus, Uppal Road, Hyderabad 500007, India
| | - Ankit Roy
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
| | - Bakthisaran Raman
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
| | - Shobha P Kruparani
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India
| | - Rajan Sankaranarayanan
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India.
- Academy of Scientific and Innovative Research (AcSIR), CSIR-CCMB campus, Uppal Road, Hyderabad 500007, India
| |
Collapse
|
5
|
Mazzoli R. Metabolic engineering strategies for consolidated production of lactic acid from lignocellulosic biomass. Biotechnol Appl Biochem 2020; 67:61-72. [DOI: 10.1002/bab.1869] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 12/05/2019] [Indexed: 01/04/2023]
Affiliation(s)
- Roberto Mazzoli
- Structural and Functional BiochemistryLaboratory of Proteomics and Metabolic Engineering of ProkaryotesDepartment of Life Sciences and Systems BiologyUniversity of Torino Torino Italy
| |
Collapse
|
6
|
Alarcon-Valdes P, Villalobos G, Martinez-Flores WA, Lopez-Escamilla E, Gonzalez-Arenas NR, Romero-Valdovinos M, Martinez-Hernandez F, Santillan-Benitez JG, Maravilla P. Can the pyruvate: ferredoxin oxidoreductase (PFOR) gene be used as an additional marker to discriminate among Blastocystis strains or subtypes? Parasit Vectors 2018; 11:564. [PMID: 30373630 PMCID: PMC6205798 DOI: 10.1186/s13071-018-3141-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/10/2018] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Blastocystis spp. are the most prevalent intestinal eukaryotes identified in humans, with at least 17 genetic subtypes (ST) based on genes coding for the small-subunit ribosomal RNA (18S). It has been argued that the 18S gene should not be the marker of choice to discriminate between STs of these strains because this marker exhibits high intra-genomic polymorphism. By contrast, pyruvate:ferredoxin oxidoreductase (PFOR) is a relevant enzyme involved in the core energy metabolism of many anaerobic microorganisms such as Blastocystis, which, in other protozoa, shows more polymorphisms than the 18S gene and thus may offer finer discrimination when trying to identify Blastocystis ST. Therefore, the objective of the present study was to assess the suitability of the PFOR gene as an additional marker to discriminate among Blastocystis strains or subtypes from symptomatic carrier children. METHODS Faecal samples from 192 children with gastrointestinal symptoms from the State of Mexico were submitted for coprological study. Twenty-one of these samples were positive only for Blastocystis spp.; these samples were analysed by PCR sequencing of regions of the 18S and PFOR genes. The amplicons were purified and sequenced; afterwards, both markers were assessed for genetic diversity. RESULTS The 18S analysis showed the following frequencies of Blastocystis subtypes: ST3 = 43%; ST1 = 38%; ST2 = 14%; and ST7 = 5%. Additionally, using subtype-specific primer sets, two samples showed mixed Blastocystis ST1 and ST2 infection. For PFOR, Bayesian inference revealed the presence of three clades (I-III); two of them grouped different ST samples, and one grouped six samples of ST3 (III). Nucleotide diversity (π) and haplotype polymorphism (θ) for the 18S analysis were similar for ST1 and ST2 (π = ~0.025 and θ = ~0.036); remarkably, ST3 showed almost 10-fold lower values. For PFOR, a similar trend was found: clade I and II had π = ~0.05 and θ = ~0.05, whereas for clade III, the values were almost 6-fold lower. CONCLUSIONS Although the fragment of the PFOR gene analysed in the present study did not allow discrimination between Blastocystis STs, this marker grouped the samples in three clades with strengthened support, suggesting that PFOR may be under different selective pressures and evolutionary histories than the 18S gene. Interestingly, the ST3 sequences showed lower variability with probable purifying selection in both markers, meaning that evolutionary forces drive differential processes among Blastocystis STs.
Collapse
Affiliation(s)
- Patricia Alarcon-Valdes
- Facultad de Quimica, Universidad Autonoma del Estado de Mexico (UAEMex), Paseo Colon esq. Paseo Tollocan, Toluca, Estado de Mexico, Mexico
| | - Guiehdani Villalobos
- Instituto de Ecologia, Universidad Nacional Autonoma de Mexico (UNAM), 04510, Ciudad de Mexico, Ciudad de Mexico, Mexico
| | | | - Eduardo Lopez-Escamilla
- Hospital General "Dr. Manuel Gea Gonzalez", Calzada de Tlalpan 4800, Ciudad de Mexico, 14080, Ciudad de Mexico, Mexico
| | - Nelly Raquel Gonzalez-Arenas
- Hospital General "Dr. Manuel Gea Gonzalez", Calzada de Tlalpan 4800, Ciudad de Mexico, 14080, Ciudad de Mexico, Mexico
| | - Mirza Romero-Valdovinos
- Hospital General "Dr. Manuel Gea Gonzalez", Calzada de Tlalpan 4800, Ciudad de Mexico, 14080, Ciudad de Mexico, Mexico
| | - Fernando Martinez-Hernandez
- Hospital General "Dr. Manuel Gea Gonzalez", Calzada de Tlalpan 4800, Ciudad de Mexico, 14080, Ciudad de Mexico, Mexico.
| | | | - Pablo Maravilla
- Hospital General "Dr. Manuel Gea Gonzalez", Calzada de Tlalpan 4800, Ciudad de Mexico, 14080, Ciudad de Mexico, Mexico.
| |
Collapse
|
7
|
Eram MS, Ma K. Pyruvate decarboxylase activity of the acetohydroxyacid synthase of Thermotoga maritima. Biochem Biophys Rep 2016; 7:394-399. [PMID: 28955930 PMCID: PMC5613635 DOI: 10.1016/j.bbrep.2016.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 06/20/2016] [Accepted: 07/13/2016] [Indexed: 11/30/2022] Open
Abstract
Acetohydroxyacid synthase (AHAS) catalyzes the production of acetolactate from pyruvate. The enzyme from the hyperthermophilic bacterium Thermotoga maritima has been purified and characterized (kcat ~100 s−1). It was found that the same enzyme also had the ability to catalyze the production of acetaldehyde and CO2 from pyruvate, an activity of pyruvate decarboxylase (PDC) at a rate approximately 10% of its AHAS activity. Compared to the catalytic subunit, reconstitution of the individually expressed and purified catalytic and regulatory subunits of the AHAS stimulated both activities of PDC and AHAS. Both activities had similar pH and temperature profiles with an optimal pH of 7.0 and temperature of 85 °C. The enzyme kinetic parameters were determined, however, it showed a non-Michaelis-Menten kinetics for pyruvate only. This is the first report on the PDC activity of an AHAS and the second bifunctional enzyme that might be involved in the production of ethanol from pyruvate in hyperthermophilic microorganisms. The acetohydroxyacid synthase of T. maritima has pyruvate decarboxylase activity The AHAS and PDC activities share the same temperature and pH optima Reconstitution of the catalytic and regulatory subunits increases both PDC and AHAS activities
Collapse
Affiliation(s)
- Mohammad S Eram
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Kesen Ma
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
8
|
Cheng M, Yoshiyasu H, Okano K, Ohtake H, Honda K. Redirection of the Reaction Specificity of a Thermophilic Acetolactate Synthase toward Acetaldehyde Formation. PLoS One 2016; 11:e0146146. [PMID: 26731734 PMCID: PMC4701669 DOI: 10.1371/journal.pone.0146146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/13/2015] [Indexed: 11/18/2022] Open
Abstract
Acetolactate synthase and pyruvate decarboxylase are thiamine pyrophosphate-dependent enzymes that convert pyruvate into acetolactate and acetaldehyde, respectively. Although the former are encoded in the genomes of many thermophiles and hyperthermophiles, the latter has been found only in mesophilic organisms. In this study, the reaction specificity of acetolactate synthase from Thermus thermophilus was redirected to catalyze acetaldehyde formation to develop a thermophilic pyruvate decarboxylase. Error-prone PCR and mutant library screening led to the identification of a quadruple mutant with 3.1-fold higher acetaldehyde-forming activity than the wild-type. Site-directed mutagenesis experiments revealed that the increased activity of the mutant was due to H474R amino acid substitution, which likely generated two new hydrogen bonds near the thiamine pyrophosphate-binding site. These hydrogen bonds might result in the better accessibility of H+ to the substrate-cofactor-enzyme intermediate and a shift in the reaction specificity of the enzyme.
Collapse
Affiliation(s)
- Maria Cheng
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2–1 Yamadaoka, Suita, Osaka 565–0871, Japan
| | - Hayato Yoshiyasu
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2–1 Yamadaoka, Suita, Osaka 565–0871, Japan
| | - Kenji Okano
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2–1 Yamadaoka, Suita, Osaka 565–0871, Japan
| | - Hisao Ohtake
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2–1 Yamadaoka, Suita, Osaka 565–0871, Japan
| | - Kohsuke Honda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2–1 Yamadaoka, Suita, Osaka 565–0871, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7 Gobancho, Chiyoda-ku, Tokyo 102–0076, Japan
- * E-mail:
| |
Collapse
|
9
|
Genetic, Genomic, and Transcriptomic Studies of Pyruvate Metabolism in Methanosarcina barkeri Fusaro. J Bacteriol 2015; 197:3592-600. [PMID: 26350133 DOI: 10.1128/jb.00551-15] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 08/28/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Pyruvate, a central intermediate in the carbon fixation pathway of methanogenic archaea, is rarely used as an energy source by these organisms. The sole exception to this rule is a genetically uncharacterized Methanosarcina barkeri mutant capable of using pyruvate as a sole energy and carbon source (the Pyr(+) phenotype). Here, we provide evidence that suggests that the Pyr(+) mutant is able to metabolize pyruvate by overexpressing pyruvate ferredoxin oxidoreductase (por) and mutating genes involved in central carbon metabolism. Genomic analysis showed that the Pyr(+) strain has two mutations localized to Mbar_A1588, the biotin protein ligase subunit of the pyruvate carboxylase (pyc) operon, and Mbar_A2165, a putative transcriptional regulator. Mutants expressing the Mbar_A1588 mutation showed no growth defect compared to the wild type (WT), yet the strains lacked pyc activity. Recreation of the Mbar_A2165 mutation resulted in a 2-fold increase of Por activity and gene expression, suggesting a role in por transcriptional regulation. Further transcriptomic analysis revealed that Pyr(+) strains also overexpress the gene encoding phosphoenolpyruvate carboxylase, indicating the presence of a previously uncharacterized route for synthesizing oxaloacetate in M. barkeri and explaining the unimpaired growth in the absence of Pyc. Surprisingly, stringent repression of the por operon was lethal, even when the media were supplemented with pyruvate and/or Casamino Acids, suggesting that por plays an unidentified essential function in M. barkeri. IMPORTANCE The work presented here reveals a complex interaction between anabolic and catabolic pathways involving pyruvate metabolism in Methanosarcina barkeri Fusaro. Among the unexpected findings were an essential role for the enzyme pyruvate-ferredoxin oxidoreductase and an alternate pathway for synthesis of oxaloacetate. These results clarify the mechanism of methanogenic catabolism of pyruvate and expand our understanding of carbon assimilation in methanogens.
Collapse
|
10
|
Eram MS, Sarafuddin B, Gong F, Ma K. Characterization of acetohydroxyacid synthase from the hyperthermophilic bacterium Thermotoga maritima. Biochem Biophys Rep 2015; 4:89-97. [PMID: 29124191 PMCID: PMC5668897 DOI: 10.1016/j.bbrep.2015.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 08/24/2015] [Accepted: 08/24/2015] [Indexed: 11/30/2022] Open
Abstract
Acetohydroxyacid synthase (AHAS) is the key enzyme in branched chain amino acid biosynthesis pathway. The enzyme activity and properties of a highly thermostable AHAS from the hyperthermophilic bacterium Thermotoga maritima is being reported. The catalytic and regulatory subunits of AHAS from T. maritima were over-expressed in Escherichia coli. The recombinant subunits were purified using a simplified procedure including a heat-treatment step followed by chromatography. A discontinuous colorimetric assay method was optimized and used to determine the kinetic parameters. AHAS activity was determined to be present in several Thermotogales including T. maritima. The catalytic subunit of T. maritima AHAS was purified approximately 30-fold, with an AHAS activity of approximately 160±27 U/mg and native molecular mass of 156±6 kDa. The regulatory subunit was purified to homogeneity and showed no catalytic activity as expected. The optimum pH and temperature for AHAS activity were 7.0 and 85 °C, respectively. The apparent Km and Vmax for pyruvate were 16.4±2 mM and 246±7 U/mg, respectively. Reconstitution of the catalytic and regulatory subunits led to increased AHAS activity. This is the first report on characterization of an isoleucine, leucine, and valine operon (ilv operon) enzyme from a hyperthermophilic microorganism and may contribute to our understanding of the physiological pathways in Thermotogales. The enzyme represents the most active and thermostable AHAS reported so far. First report of AHAS from a hyperthermophilic bacterium. Catalytic and regulatory subunits of AHAS of T. maritima was expressed in E. coli. Recombinant proteins were purified using a simplified procedure. Enzyme represents the most active and thermostable AHAS reported so far. Kinetic parameters were determined for the purified recombinant enzyme
Collapse
Key Words
- AHAS, acetohydroxyacid synthase
- Acetohydroxyacid synthase
- BCAA, branched chain amino acid
- Branched-chain amino acids
- CCE, crude cell extract
- CFE, cell-free extract
- HTCCE, heat-treated crude cell extract
- Hyperthermophiles
- IB, inclusion body
- IMAC, immobilized metal affinity chromatography
- TPP, thiamine pyrophosphate
- Thermotogales
- TmAHAS, Thermotoga maritima acetohydroxyacid synthase
- ilv, isoleucine, leucine, valine
Collapse
Affiliation(s)
- Mohammad S Eram
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Benozir Sarafuddin
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Frank Gong
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| | - Kesen Ma
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
| |
Collapse
|
11
|
Eram MS, Wong A, Oduaran E, Ma K. Molecular and biochemical characterization of bifunctional pyruvate decarboxylases and pyruvate ferredoxin oxidoreductases from Thermotoga maritima and Thermotoga hypogea. J Biochem 2015; 158:459-66. [PMID: 26032540 DOI: 10.1093/jb/mvv058] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/06/2015] [Indexed: 11/13/2022] Open
Abstract
Hyperthermophilic bacteria Thermotoga maritima and Thermotoga hypogea produce ethanol as a metabolic end product, which is resulted from acetaldehyde reduction catalysed by an alcohol dehydrogenase (ADH). However, the enzyme that is involved in the production of acetaldehyde from pyruvate is not well characterized. An oxygen sensitive and coenzyme A-dependent pyruvate decarboxylase (PDC) activity was found to be present in cell free extracts of T. maritima and T. hypogea. Both enzymes were purified and found to have pyruvate ferredoxin oxidoreductase (POR) activity, indicating their bifunctionality. Both PDC and POR activities from each of the purified enzymes were characterized in regards to their optimal assay conditions including pH dependency, oxygen sensitivity, thermal stability, temperature dependency and kinetic parameters. The close relatedness of the PORs that was shown by sequence analysis could be an indication of the presence of such bifunctionality in other hyperthermophilic bacteria. This is the first report of a bifunctional PDC/POR enzyme in hyperthermophilic bacteria. The PDC and the previously reported ADHs are most likely the key enzymes catalysing the production of ethanol from pyruvate in bacterial hyperthermophiles.
Collapse
Affiliation(s)
- Mohammad S Eram
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada and
| | - Alton Wong
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada and
| | - Erica Oduaran
- Department of Chemistry and Physics, Roger Williams University, One Old Ferry Road, Bristol, RI 02809, USA
| | - Kesen Ma
- Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada and
| |
Collapse
|
12
|
Olson DG, Sparling R, Lynd LR. Ethanol production by engineered thermophiles. Curr Opin Biotechnol 2015; 33:130-41. [PMID: 25745810 DOI: 10.1016/j.copbio.2015.02.006] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/11/2015] [Accepted: 02/13/2015] [Indexed: 12/17/2022]
Abstract
We compare a number of different strategies that have been pursued to engineer thermophilic microorganisms for increased ethanol production. Ethanol production from pyruvate can proceed via one of four pathways, which are named by the key pyruvate dissimilating enzyme: pyruvate decarboxylase (PDC), pyruvate dehydrogenase (PDH), pyruvate formate lyase (PFL), and pyruvate ferredoxin oxidoreductase (PFOR). For each of these pathways except PFL, we see examples where ethanol production has been engineered with a yield of >90% of the theoretical maximum. In each of these cases, this engineering was achieved mainly by modulating expression of native genes. We have not found an example where a thermophilic ethanol production pathway has been transferred to a non-ethanol-producing organism to produce ethanol at high yield. A key reason for the lack of transferability of ethanol production pathways is the current lack of understanding of the enzymes involved.
Collapse
Affiliation(s)
- Daniel G Olson
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States
| | - Richard Sparling
- Department of Microbiology, University of Manitoba, Winnipeg, MB, Canada R3T 5V6
| | - Lee R Lynd
- Thayer School of Engineering at Dartmouth College, Hanover, NH 03755, United States; BioEnergy Science Center, Oak Ridge, TN 37830, United States.
| |
Collapse
|
13
|
Zhou J, Olson DG, Lanahan AA, Tian L, Murphy SJL, Lo J, Lynd LR. Physiological roles of pyruvate ferredoxin oxidoreductase and pyruvate formate-lyase in Thermoanaerobacterium saccharolyticum JW/SL-YS485. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:138. [PMID: 26379770 PMCID: PMC4570089 DOI: 10.1186/s13068-015-0304-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 08/03/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND Thermoanaerobacter saccharolyticum is a thermophilic microorganism that has been engineered to produce ethanol at high titer (30-70 g/L) and greater than 90 % theoretical yield. However, few genes involved in pyruvate to ethanol production pathway have been unambiguously identified. In T. saccharolyticum, the products of six putative pfor gene clusters and one pfl gene may be responsible for the conversion of pyruvate to acetyl-CoA. To gain insights into the physiological roles of PFOR and PFL, we studied the effect of deletions of several genes thought to encode these activities. RESULTS It was found that pyruvate ferredoxin oxidoreductase enzyme (PFOR) is encoded by the pforA gene and plays a key role in pyruvate dissimilation. We further demonstrated that pyruvate formate-lyase activity (PFL) is encoded by the pfl gene. Although the pfl gene is normally expressed at low levels, it is crucial for biosynthesis in T. saccharolyticum. In pforA deletion strains, pfl expression increased and was able to partially compensate for the loss of PFOR activity. Deletion of both pforA and pfl resulted in a strain that required acetate and formate for growth and produced lactate as the primary fermentation product, achieving 88 % theoretical lactate yield. CONCLUSION PFOR encoded by Tsac_0046 and PFL encoded by Tsac_0628 are only two routes for converting pyruvate to acetyl-CoA in T. saccharolyticum. The physiological role of PFOR is pyruvate dissimilation, whereas that of PFL is supplying C1 units for biosynthesis.
Collapse
Affiliation(s)
- Jilai Zhou
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Daniel G Olson
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Anthony A Lanahan
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Liang Tian
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Sean Jean-Loup Murphy
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Jonathan Lo
- />Department of Biological Sciences at Dartmouth College, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| | - Lee R Lynd
- />Thayer School of Engineering, Hanover, NH 03755 USA
- />Department of Biological Sciences at Dartmouth College, Hanover, NH 03755 USA
- />BioEnergy Science Center, Oak Ridge, TN 37830 USA
| |
Collapse
|
14
|
Aklujkar M, Risso C, Smith J, Beaulieu D, Dubay R, Giloteaux L, DiBurro K, Holmes D. Anaerobic degradation of aromatic amino acids by the hyperthermophilic archaeon Ferroglobus placidus. Microbiology (Reading) 2014; 160:2694-2709. [DOI: 10.1099/mic.0.083261-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Ferroglobus placidus was discovered to oxidize completely the aromatic amino acids tyrosine, phenylalanine and tryptophan when Fe(III) oxide was provided as an electron acceptor. This property had not been reported previously for a hyperthermophilic archaeon. It appeared that F. placidus follows a pathway for phenylalanine and tryptophan degradation similar to that of mesophilic nitrate-reducing bacteria, Thauera aromatica and Aromatoleum aromaticum EbN1. Phenylacetate, 4-hydroxyphenylacetate and indole-3-acetate were formed during anaerobic degradation of phenylalanine, tyrosine and tryptophan, respectively. Candidate genes for enzymes involved in the anaerobic oxidation of phenylalanine to phenylacetate (phenylalanine transaminase, phenylpyruvate decarboxylase and phenylacetaldehyde : ferredoxin oxidoreductase) were identified in the F. placidus genome. In addition, transcription of candidate genes for the anaerobic phenylacetate degradation, benzoyl-CoA degradation and glutaryl-CoA degradation pathways was significantly upregulated in microarray and quantitative real-time-PCR studies comparing phenylacetate-grown cells with acetate-grown cells. These results suggested that the general strategies for anaerobic degradation of aromatic amino acids are highly conserved amongst bacteria and archaea living in both mesophilic and hyperthermophilic environments. They also provided insights into the diverse metabolism of Archaeoglobaceae species living in hyperthermophilic environments.
Collapse
Affiliation(s)
- Muktak Aklujkar
- Department of Biological Sciences, Towson University, Towson, MD, USA
| | - Carla Risso
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - Jessica Smith
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - Derek Beaulieu
- Department of Physical and Biological Sciences, Western New England University, Springfield, MA, USA
| | - Ryan Dubay
- Department of Physical and Biological Sciences, Western New England University, Springfield, MA, USA
| | - Ludovic Giloteaux
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - Kristin DiBurro
- Department of Microbiology, University of Massachusetts, Amherst, MA, USA
| | - Dawn Holmes
- Department of Physical and Biological Sciences, Western New England University, Springfield, MA, USA
| |
Collapse
|
15
|
van Zyl LJ, Schubert WD, Tuffin MI, Cowan DA. Structure and functional characterization of pyruvate decarboxylase from Gluconacetobacter diazotrophicus. BMC STRUCTURAL BIOLOGY 2014; 14:21. [PMID: 25369873 PMCID: PMC4428508 DOI: 10.1186/s12900-014-0021-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 09/25/2014] [Indexed: 11/10/2022]
Abstract
BACKGROUND Bacterial pyruvate decarboxylases (PDC) are rare. Their role in ethanol production and in bacterially mediated ethanologenic processes has, however, ensured a continued and growing interest. PDCs from Zymomonas mobilis (ZmPDC), Zymobacter palmae (ZpPDC) and Sarcina ventriculi (SvPDC) have been characterized and ZmPDC has been produced successfully in a range of heterologous hosts. PDCs from the Acetobacteraceae and their role in metabolism have not been characterized to the same extent. Examples include Gluconobacter oxydans (GoPDC), G. diazotrophicus (GdPDC) and Acetobacter pasteutrianus (ApPDC). All of these organisms are of commercial importance. RESULTS This study reports the kinetic characterization and the crystal structure of a PDC from Gluconacetobacter diazotrophicus (GdPDC). Enzyme kinetic analysis indicates a high affinity for pyruvate (K M 0.06 mM at pH 5), high catalytic efficiencies (1.3 • 10(6) M(-1) • s(-1) at pH 5), pHopt of 5.5 and Topt at 45°C. The enzyme is not thermostable (T½ of 18 minutes at 60°C) and the calculated number of bonds between monomers and dimers do not give clear indications for the relatively lower thermostability compared to other PDCs. The structure is highly similar to those described for Z. mobilis (ZmPDC) and A. pasteurianus PDC (ApPDC) with a rmsd value of 0.57 Å for Cα when comparing GdPDC to that of ApPDC. Indole-3-pyruvate does not serve as a substrate for the enzyme. Structural differences occur in two loci, involving the regions Thr341 to Thr352 and Asn499 to Asp503. CONCLUSIONS This is the first study of the PDC from G. diazotrophicus (PAL5) and lays the groundwork for future research into its role in this endosymbiont. The crystal structure of GdPDC indicates the enzyme to be evolutionarily closely related to homologues from Z. mobilis and A. pasteurianus and suggests strong selective pressure to keep the enzyme characteristics in a narrow range. The pH optimum together with reduced thermostability likely reflect the host organisms niche and conditions under which these properties have been naturally selected for. The lack of activity on indole-3-pyruvate excludes this decarboxylase as the enzyme responsible for indole acetic acid production in G. diazotrophicus.
Collapse
Affiliation(s)
- Leonardo J van Zyl
- Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Robert Sobukwe Road, Bellville, Cape Town, South Africa.
| | - Wolf-Dieter Schubert
- Department of Biochemistry, University of Pretoria, 2 Lynnwood Road, Pretoria, 0002, South Africa.
| | - Marla I Tuffin
- Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Robert Sobukwe Road, Bellville, Cape Town, South Africa.
| | - Don A Cowan
- Department of Genetics, University of Pretoria, Pretoria, 0002, South Africa.
| |
Collapse
|