1
|
Schiaffi V, Barras F, Bouveret E. Matching the β-oxidation gene repertoire with the wide diversity of fatty acids. Curr Opin Microbiol 2024; 77:102402. [PMID: 37992547 DOI: 10.1016/j.mib.2023.102402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 10/23/2023] [Accepted: 10/28/2023] [Indexed: 11/24/2023]
Abstract
Bacteria can use fatty acids (FAs) from their environment as carbon and energy source. This catabolism is performed by the enzymes of the well-known β-oxidation machinery, producing reducing power and releasing acetyl-CoA that can feed the tricarboxylic acid cycle. FAs are extremely diverse: they can be saturated or (poly)unsaturated and are found in different sizes. The need to degrade such a wide variety of compounds may explain why so many seemingly homologous enzymes are found for each step of the β-oxidation cycle. In addition, the degradation of unsaturated fatty acids requires specific auxiliary enzymes for isomerase and reductase reactions. Furthermore, the β-oxidation cycle can be blocked by dead-end products, which are taken care of by acyl-CoA thioesterases. Yet, the functional characterization of the enzymes required for the degradation of the full diversity of FAs remains to be documented in most bacteria.
Collapse
Affiliation(s)
- Veronica Schiaffi
- Institut Pasteur, Department of Microbiology, Université Paris-Cité, UMR CNRS 6047, SAMe Unit, France
| | - Frédéric Barras
- Institut Pasteur, Department of Microbiology, Université Paris-Cité, UMR CNRS 6047, SAMe Unit, France
| | - Emmanuelle Bouveret
- Institut Pasteur, Department of Microbiology, Université Paris-Cité, UMR CNRS 6047, SAMe Unit, France.
| |
Collapse
|
2
|
Peña-Montenegro TD, Kleindienst S, Allen AE, Eren AM, McCrow JP, Sánchez-Calderón JD, Arnold J, Joye SB. Species-specific responses of marine bacteria to environmental perturbation. ISME COMMUNICATIONS 2023; 3:99. [PMID: 37736763 PMCID: PMC10516948 DOI: 10.1038/s43705-023-00310-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 09/05/2023] [Accepted: 09/13/2023] [Indexed: 09/23/2023]
Abstract
Environmental perturbations shape the structure and function of microbial communities. Oil spills are a major perturbation and resolving spills often requires active measures like dispersant application that can exacerbate the initial disturbance. Species-specific responses of microorganisms to oil and dispersant exposure during such perturbations remain largely unknown. We merged metatranscriptomic libraries with pangenomes to generate Core-Accessory Metatranscriptomes (CA-Metatranscriptomes) for two microbial hydrocarbon degraders that played important roles in the aftermath of the Deepwater Horizon oil spill. The Colwellia CA-Metatranscriptome illustrated pronounced dispersant-driven acceleration of core (~41%) and accessory gene (~59%) transcription, suggesting an opportunistic strategy. Marinobacter responded to oil exposure by expressing mainly accessory genes (~93%), suggesting an effective hydrocarbon-degrading lifestyle. The CA-Metatranscriptome approach offers a robust way to identify the underlying mechanisms of key microbial functions and highlights differences of specialist-vs-opportunistic responses to environmental disturbance.
Collapse
Affiliation(s)
- Tito D Peña-Montenegro
- Department of Marine Sciences, University of Georgia, 325 Sanford Dr., Athens, GA, 30602-3636, USA
- Institute of Bioinformatics, University of Georgia, 120 Green St., Athens, GA, 30602-7229, USA
- Grupo de Investigación y Desarrollo en Ciencias, Tecnología e Innovación (BioGRID), Sociedad de Doctores e Investigadores de Colombia (SoPhIC), Bogotá, Colombia
| | - Sara Kleindienst
- Department of Marine Sciences, University of Georgia, 325 Sanford Dr., Athens, GA, 30602-3636, USA
- Department of Environmental Microbiology, Institute for Sanitary Engineering, Water Quality and Solid Waste Management (ISWA), University of Stuttgart, Bandtäle 2, 70569, Stuttgart, Germany
| | - Andrew E Allen
- Microbial and Environmental Genomics, J. Craig Venter Institute, La Jolla, CA, 92037, USA
- Integrative Oceanography Division, Scripps Institution of Oceanography, UC San Diego, La Jolla, CA, 92037, USA
| | - A Murat Eren
- Helmholtz Institute for Functional Marine Biodiversity at the University of Oldenburg, University of Oldenburg, Oldenburg, 26129, Germany
- Josephine Bay Paul Center, Marine Biological Laboratory, Woods Hole, MA, USA
| | - John P McCrow
- Microbial and Environmental Genomics, J. Craig Venter Institute, La Jolla, CA, 92037, USA
| | - Juan D Sánchez-Calderón
- Grupo de Investigación en Gestión Ecológica y Agroindustrial (GEA), Programa de Microbiología, Facultad de Ciencias Exactas y Naturales, Universidad Libre, Seccional Barranquilla, Barranquilla, Colombia
| | - Jonathan Arnold
- Institute of Bioinformatics, University of Georgia, 120 Green St., Athens, GA, 30602-7229, USA
- Department of Genetics, University of Georgia, 120 Green St., Athens, GA, 30602-7223, USA
| | - Samantha B Joye
- Department of Marine Sciences, University of Georgia, 325 Sanford Dr., Athens, GA, 30602-3636, USA.
| |
Collapse
|
3
|
McNaught KJ, Kuatsjah E, Zahn M, Prates ÉT, Shao H, Bentley GJ, Pickford AR, Gruber JN, Hestmark KV, Jacobson DA, Poirier BC, Ling C, San Marchi M, Michener WE, Nicora CD, Sanders JN, Szostkiewicz CJ, Veličković D, Zhou M, Munoz N, Kim YM, Magnuson JK, Burnum-Johnson KE, Houk KN, McGeehan JE, Johnson CW, Beckham GT. Initiation of fatty acid biosynthesis in Pseudomonas putida KT2440. Metab Eng 2023; 76:193-203. [PMID: 36796578 DOI: 10.1016/j.ymben.2023.02.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023]
Abstract
Deciphering the mechanisms of bacterial fatty acid biosynthesis is crucial for both the engineering of bacterial hosts to produce fatty acid-derived molecules and the development of new antibiotics. However, gaps in our understanding of the initiation of fatty acid biosynthesis remain. Here, we demonstrate that the industrially relevant microbe Pseudomonas putida KT2440 contains three distinct pathways to initiate fatty acid biosynthesis. The first two routes employ conventional β-ketoacyl-ACP synthase III enzymes, FabH1 and FabH2, that accept short- and medium-chain-length acyl-CoAs, respectively. The third route utilizes a malonyl-ACP decarboxylase enzyme, MadB. A combination of exhaustive in vivo alanine-scanning mutagenesis, in vitro biochemical characterization, X-ray crystallography, and computational modeling elucidate the presumptive mechanism of malonyl-ACP decarboxylation via MadB. Given that functional homologs of MadB are widespread throughout domain Bacteria, this ubiquitous alternative fatty acid initiation pathway provides new opportunities to target a range of biotechnology and biomedical applications.
Collapse
Affiliation(s)
- Kevin J McNaught
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; DOE Agile BioFoundry, Emeryville, CA, 94608, USA
| | - Eugene Kuatsjah
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Michael Zahn
- Centre for Enzyme Innovation, School of Biological Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
| | - Érica T Prates
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Huiling Shao
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA, 90095, USA
| | - Gayle J Bentley
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; DOE Agile BioFoundry, Emeryville, CA, 94608, USA
| | - Andrew R Pickford
- Centre for Enzyme Innovation, School of Biological Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
| | - Josephine N Gruber
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Kelley V Hestmark
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; DOE Agile BioFoundry, Emeryville, CA, 94608, USA
| | - Daniel A Jacobson
- Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA; Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA
| | - Brenton C Poirier
- DOE Agile BioFoundry, Emeryville, CA, 94608, USA; Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Chen Ling
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; DOE Agile BioFoundry, Emeryville, CA, 94608, USA
| | - Myrsini San Marchi
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA, 90095, USA
| | - William E Michener
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA
| | - Carrie D Nicora
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Jacob N Sanders
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA, 90095, USA
| | - Caralyn J Szostkiewicz
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; DOE Agile BioFoundry, Emeryville, CA, 94608, USA
| | - Dušan Veličković
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Mowei Zhou
- Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Nathalie Munoz
- DOE Agile BioFoundry, Emeryville, CA, 94608, USA; Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - Young-Mo Kim
- DOE Agile BioFoundry, Emeryville, CA, 94608, USA; Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Jon K Magnuson
- DOE Agile BioFoundry, Emeryville, CA, 94608, USA; Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, 99352, USA
| | - Kristin E Burnum-Johnson
- DOE Agile BioFoundry, Emeryville, CA, 94608, USA; Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA, 99354, USA
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California Los Angeles, CA, 90095, USA
| | - John E McGeehan
- Centre for Enzyme Innovation, School of Biological Sciences, Institute of Biological and Biomedical Sciences, University of Portsmouth, Portsmouth, PO1 2DY, UK
| | - Christopher W Johnson
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; DOE Agile BioFoundry, Emeryville, CA, 94608, USA
| | - Gregg T Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, 80401, USA; DOE Agile BioFoundry, Emeryville, CA, 94608, USA; Center for Bioenergy Innovation, Oak Ridge National Laboratory, Oak Ridge, TN, 37830, USA.
| |
Collapse
|
4
|
Zhuo XZ, Chou SC, Li SY. Producing medium-chain-length polyhydroxyalkanoate from diverse feedstocks by deregulating unsaturated fatty acid biosynthesis in Escherichia coli. BIORESOURCE TECHNOLOGY 2022; 365:128078. [PMID: 36216288 DOI: 10.1016/j.biortech.2022.128078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/01/2022] [Accepted: 10/03/2022] [Indexed: 06/16/2023]
Abstract
The fatty acid metabolism in Escherichia coli has served as a basic metabolic chassis for medium-chain-length polyhydroxyalkanoate (mcl-PHA) production. In this study, the phaG and phaC1 genes from Pseudomonas entomophila L48 were first cloned as pGRN08. E. coli BL21P (E. coli BL21(DE3) ΔptsG) containing pGRN08 was able to produce 23 ± 3 and 7 ± 0 mg/L homopolymer poly(3-hydroxydecanoate)(P(3HD)) from glucose and xylose, respectively. Next, a gene, PSEEN0908 (encoding a putative 3-hydroxyacyl-CoA ligase), from P. entomophila L48 was found to increase the performance of mcl-PHA production. The induction of the fatty acid biosynthesis repressor (FabR), a transcription regulator that represses UFA biosynthesis, in E. coli substantially increased the mcl-PHA production by an order of magnitude from both unrelated and related carbon source conversion. A mcl-PHA concentration of 179 ± 1 mg/L and a content of 5.79 ± 0.16 % were obtained, where 31 mol% was 3-hydroxyoctanoate (3HO) and 69 mol% was 3HD.
Collapse
Affiliation(s)
- Xiao-Zhen Zhuo
- Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan
| | - Shu-Chiao Chou
- Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan
| | - Si-Yu Li
- Department of Chemical Engineering, National Chung Hsing University, Taichung 402, Taiwan; Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University, Taichung 402, Taiwan.
| |
Collapse
|
5
|
Wang XY, Xie J. Response to Cold Adaption in Acinetobacter johnsonii XY27 from Spoiled Bigeye Tuna ( Thunnus obesus): Membrane Protein Composition and Protein Biomarker Identification by Proteomics. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:10000-10010. [PMID: 35919963 DOI: 10.1021/acs.jafc.2c03303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Acinetobacter johnsonii is one of the major food-spoilage bacteria and can survive under cold stress. In this study, the membrane composition, membrane permeability, and energy transduction of A. johnsonii XY27 cultured at 4 and 30 °C were examined comparatively by flow cytometry combined with liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. The Na+/K+ATPase activity, alkaline phosphatase and ATPase activity, fluorescence intensity, and cell viability in A. johnsonii XY27 increased with the decrease in cultivation temperature. The polyunsaturated fatty acid and monounsaturated fatty acids have a higher content in A. johnsonii XY27 cultured at 4 °C compared to that cultured at 30 °C, in which the contents of methyl palmitoleate, methyl myristoleate, and methyl oleate increased dramatically with decreasing temperature. Comparative proteomics analysis revealed that 31 proteins were downregulated and 4 proteins were upregulated, in which catalase-peroxidase 1 and cold shock proteins as biomarker proteins could effectively control A. johnsonii during cold adaptation.
Collapse
Affiliation(s)
- Xin-Yun Wang
- Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai Ocean University, Shanghai 201306, China
- Shanghai Professional Technology Service Platform on Cold Chain Equipment Performance and Energy Saving Evaluation, Shanghai Ocean University, Shanghai 201306, China
- National Experimental Teaching Demonstration Center for Food Science and Engineering Shanghai Ocean University, Shanghai Ocean University, Shanghai 201306, China
- College of Food Science & Technology, Shanghai Ocean University, Shanghai 201306, China
| | - Jing Xie
- Shanghai Engineering Research Center of Aquatic Product Processing & Preservation, Shanghai Ocean University, Shanghai 201306, China
- Shanghai Professional Technology Service Platform on Cold Chain Equipment Performance and Energy Saving Evaluation, Shanghai Ocean University, Shanghai 201306, China
- National Experimental Teaching Demonstration Center for Food Science and Engineering Shanghai Ocean University, Shanghai Ocean University, Shanghai 201306, China
- College of Food Science & Technology, Shanghai Ocean University, Shanghai 201306, China
| |
Collapse
|
6
|
Degradation of Exogenous Fatty Acids in Escherichia coli. Biomolecules 2022; 12:biom12081019. [PMID: 35892328 PMCID: PMC9329746 DOI: 10.3390/biom12081019] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/19/2022] [Accepted: 07/19/2022] [Indexed: 12/10/2022] Open
Abstract
Many bacteria possess all the machineries required to grow on fatty acids (FA) as a unique source of carbon and energy. FA degradation proceeds through the β-oxidation cycle that produces acetyl-CoA and reduced NADH and FADH cofactors. In addition to all the enzymes required for β-oxidation, FA degradation also depends on sophisticated systems for its genetic regulation and for FA transport. The fact that these machineries are conserved in bacteria suggests a crucial role in environmental conditions, especially for enterobacteria. Bacteria also possess specific enzymes required for the degradation of FAs from their environment, again showing the importance of this metabolism for bacterial adaptation. In this review, we mainly describe FA degradation in the Escherichia coli model, and along the way, we highlight and discuss important aspects of this metabolism that are still unclear. We do not detail exhaustively the diversity of the machineries found in other bacteria, but we mention them if they bring additional information or enlightenment on specific aspects.
Collapse
|
7
|
Kasari M, Kasari V, Kärmas M, Jõers A. Decoupling Growth and Production by Removing the Origin of Replication from a Bacterial Chromosome. ACS Synth Biol 2022; 11:2610-2622. [PMID: 35798328 DOI: 10.1021/acssynbio.1c00618] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Efficient production of biochemicals and proteins in cell factories frequently benefits from a two-stage bioprocess in which growth and production phases are decoupled. Here, we describe a novel growth switch based on the permanent removal of the origin of replication (oriC) from the Escherichia coli chromosome. Without oriC, cells cannot initiate a new round of replication, and they stop growing while their metabolism remains active. Our system relies on a serine recombinase from bacteriophage phiC31 whose expression is controlled by the temperature-sensitive cI857 repressor from phage lambda. The reporter protein expression in switched cells continues after cessation of growth, leading to protein levels up to 5 times higher compared to nonswitching cells. Switching induces a unique physiological state that is different from both normal exponential and stationary phases. The switched cells remain in this state even when not growing, retain their protein synthesis capacity, and do not induce proteins associated with the stationary phase. Our switcher technology is potentially useful for a range of products and applicable in many bacterial species for decoupling growth and production.
Collapse
Affiliation(s)
- Marje Kasari
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
| | - Villu Kasari
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
| | - Mirjam Kärmas
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
| | - Arvi Jõers
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
| |
Collapse
|
8
|
Li Y, Wang J, Wang F, Wang L, Wang L, Xu Z, Yuan H, Yang X, Li P, Su J, Wang R. Production of 10-Hydroxy-2-decenoic Acid from Decanoic Acid via Whole-Cell Catalysis in Engineered Escherichia coli. CHEMSUSCHEM 2022; 15:e202102152. [PMID: 34796684 DOI: 10.1002/cssc.202102152] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/18/2021] [Indexed: 06/13/2023]
Abstract
10-Hydroxy-2-decenoic acid (10-HDA) is a terminal hydroxylated medium-chain α,β-unsaturated carboxylic acid that performs various unique physiological activities and has a wide market value. Therefore, development of an environmentally friendly, safe, and high-efficiency route to synthesize 10-HDA is required. Here, the β-oxidation pathway of Escherichia coli was modified and a P450 terminal hydroxylase (CYP153A33-CPRBM3 ) was rationally designed to synthesize 10-HDA using decanoic acid as a substrate via two-step whole-cell catalysis. Different homologues of FadDs, FadEs, and YdiIs were analyzed in the first step of the conversion of decanoic acid to trans- -2- decenoic acid. In the second step, CYP153A33 (M228L)-CPRBM3 efficiently catalyzed the conversion of trans- -2- decenoic acid to 10-HDA. Finally, 217 mg L-1 10-HDA was obtained with 500 mg L-1 decanoic acid. This study provides a strategy for biosynthesis of 10-HDA and other α, β-unsaturated carboxylic acid derivatives from specific fatty acids.
Collapse
Affiliation(s)
- Yan Li
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Junqing Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Fen Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Li Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Leilei Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Ziqi Xu
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Haibo Yuan
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Xiaohui Yang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Piwu Li
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Jing Su
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| | - Ruiming Wang
- State Key Laboratory of Biobased Material and Green Papermaking (LBMP), Jinan, Shandong, 250353, P. R. China
- Key Laboratory of Shandong Microbial Engineering, QILU University of Technology, Shandong Academy of Sciences, Jinan, Shandong, 250353, P. R. China
| |
Collapse
|
9
|
Sarwar A, Nguyen LT, Lee EY. Bio-upgrading of ethanol to fatty acid ethyl esters by metabolic engineering of Pseudomonas putida KT2440. BIORESOURCE TECHNOLOGY 2022; 350:126899. [PMID: 35217159 DOI: 10.1016/j.biortech.2022.126899] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Revised: 02/19/2022] [Accepted: 02/21/2022] [Indexed: 06/14/2023]
Abstract
Fatty acid ethyl esters (FAEEs) have gained increasing attention as a replacement for traditional fossil fuels in the recent years. Here, we report the efficient upgrading of ethanol to FAEEs from Pseudomonas putida KT2440, using ethanol as the sole carbon source. First, the wax synthase (WS) encoded by the atfA gene from Acinetobacter baylyi ADP1 was expressed in P. putida KT2440. Second, the flux from ethanol towards acetyl-CoA was increased by expression of the acetaldehyde dehydrogenase (ada) from Dickeya zeae. By using dodecane overlay to capture FAEEs, 1.2 g/L of FAEEs with a yield of 152.09 mg FAEEs/g ethanol were produced. Culture optimization enhanced the FAEEs contents up to 1.6 g/L in shake flask and 4.3 g/L in a fed-batch fermenter. In summary, our study provides a basis for combining the bioethanol production process with the efficient upgrading of ethanol to biodiesel.
Collapse
Affiliation(s)
- Arslan Sarwar
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Linh Thanh Nguyen
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea
| | - Eun Yeol Lee
- Department of Chemical Engineering (BK21 FOUR Integrated Engineering Program), Kyung Hee University, Yongin-si, Gyeonggi-do 17104, Republic of Korea.
| |
Collapse
|
10
|
Bacterial Homologs of Progestin and AdipoQ Receptors (PAQRs) Affect Membrane Energetics Homeostasis but Not Fluidity. J Bacteriol 2022; 204:e0058321. [PMID: 35285724 PMCID: PMC9017321 DOI: 10.1128/jb.00583-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Membrane potential homeostasis is essential for cell survival. Defects in membrane potential lead to pleiotropic phenotypes, consistent with the central role of membrane energetics in cell physiology. Homologs of the progestin and AdipoQ receptors (PAQRs) are conserved in multiple phyla of Bacteria and Eukarya. In eukaryotes, PAQRs are proposed to modulate membrane fluidity and fatty acid (FA) metabolism. The role of bacterial homologs has not been elucidated. Here, we use Escherichia coli and Bacillus subtilis to show that bacterial PAQR homologs, which we name “TrhA,” have a role in membrane energetics homeostasis. Using transcriptional fusions, we show that E. coli TrhA (encoded by yqfA) is part of the unsaturated fatty acid biosynthesis regulon. Fatty acid analyses and physiological assays show that a lack of TrhA in both E. coli and B. subtilis (encoded by yplQ) provokes subtle but consistent changes in membrane fatty acid profiles that do not translate to control of membrane fluidity. Instead, membrane proteomics in E. coli suggested a disrupted energy metabolism and dysregulated membrane energetics in the mutant, though it grew similarly to its parent. These changes translated into a disturbed membrane potential in the mutant relative to its parent under various growth conditions. Similar dysregulation of membrane energetics was observed in a different E. coli strain and in the distantly related B. subtilis. Together, our findings are consistent with a role for TrhA in membrane energetics homeostasis, through a mechanism that remains to be elucidated. IMPORTANCE Eukaryotic homologs of the progestin and AdipoQ receptor family (PAQR) have been shown to regulate membrane fluidity by affecting, through unknown mechanisms, unsaturated fatty acid (FA) metabolism. The bacterial homologs studied here mediate small and consistent changes in unsaturated FA metabolism that do not seem to impact membrane fluidity but, rather, alter membrane energetics homeostasis. Together, the findings here suggest that bacterial and eukaryotic PAQRs share functions in maintaining membrane homeostasis (fluidity in eukaryotes and energetics for bacteria with TrhA homologs).
Collapse
|
11
|
Li H, Nian J, Fang S, Guo M, Huang X, Zhang F, Wang Q, Zhang J, Bai J, Dong G, Xin P, Xie X, Chen F, Wang G, Wang Y, Qian Q, Zuo J, Chu J, Ma X. Regulation of nitrogen starvation responses by the alarmone (p)ppGpp in rice. J Genet Genomics 2022; 49:469-480. [DOI: 10.1016/j.jgg.2022.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 02/14/2022] [Accepted: 02/16/2022] [Indexed: 12/20/2022]
|
12
|
The Classical, Yet Controversial, First Enzyme of Lipid Synthesis: Escherichia coli Acetyl-CoA Carboxylase. Microbiol Mol Biol Rev 2021; 85:e0003221. [PMID: 34132100 DOI: 10.1128/mmbr.00032-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Escherichia coli acetyl-CoA carboxylase (ACC), the enzyme responsible for synthesis of malonyl-CoA, the building block of fatty acid synthesis, is the paradigm bacterial ACC. Many reports on the structures and stoichiometry of the four subunits comprising the active enzyme as well as on regulation of ACC activity and expression have appeared in the almost 20 years since this subject was last reviewed. This review seeks to update and expand on these reports.
Collapse
|
13
|
Lee JY, Cha S, Lee JH, Lim HG, Noh MH, Kang CW, Jung GY. Plug-in repressor library for precise regulation of metabolic flux in Escherichia coli. Metab Eng 2021; 67:365-372. [PMID: 34333137 DOI: 10.1016/j.ymben.2021.07.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 07/10/2021] [Accepted: 07/28/2021] [Indexed: 10/20/2022]
Abstract
In metabolic engineering, enhanced production of value-added chemicals requires precise flux control between growth-essential competing and production pathways. Although advances in synthetic biology have facilitated the exploitation of a number of genetic elements for precise flux control, their use requires expensive inducers, or more importantly, needs complex and time-consuming processes to design and optimize appropriate regulator components, case-by-case. To overcome this issue, we devised the plug-in repressor libraries for target-specific flux control, in which expression levels of the repressors were diversified using degenerate 5' untranslated region (5' UTR) sequences employing the UTR Library Designer. After we validated a wide expression range of the repressor libraries, they were applied to improve the production of lycopene from glucose and 3-hydroxypropionic acid (3-HP) from acetate in Escherichia coli via precise flux rebalancing to enlarge precursor pools. Consequently, we successfully achieved optimal carbon fluxes around the precursor nodes for efficient production. The most optimized strains were observed to produce 2.59 g/L of 3-HP and 11.66 mg/L of lycopene, which were improved 16.5-fold and 2.82-fold, respectively, compared to those produced by the parental strains. These results indicate that carbon flux rebalancing using the plug-in library is a powerful strategy for efficient production of value-added chemicals in E. coli.
Collapse
Affiliation(s)
- Ji Yeon Lee
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea
| | - Sanghak Cha
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea
| | - Ji Hoon Lee
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea
| | - Hyun Gyu Lim
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea
| | - Myung Hyun Noh
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea
| | - Chae Won Kang
- Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea
| | - Gyoo Yeol Jung
- School of Interdisciplinary Bioscience and Bioengineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea; Department of Chemical Engineering, Pohang University of Science and Technology, 77 Cheongam-Ro, Nam-Gu, Pohang, Gyeongbuk, 37673, South Korea.
| |
Collapse
|
14
|
Hassoun Y, Bartoli J, Wahl A, Viala JP, Bouveret E. Dual Regulation of Phosphatidylserine Decarboxylase Expression by Envelope Stress Responses. Front Mol Biosci 2021; 8:665977. [PMID: 34026837 PMCID: PMC8138132 DOI: 10.3389/fmolb.2021.665977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/09/2021] [Indexed: 11/13/2022] Open
Abstract
Bacteria adapt to versatile environments by modulating gene expression through a set of stress response regulators, alternative Sigma factors, or two-component systems. Among the central processes that must be finely tuned is membrane homeostasis, including synthesis of phospholipids (PL). However, few genetic regulations of this process have been reported. We have previously shown that the gene coding the first step of PL synthesis is regulated by σE and ppGpp, and that the BasRS (PmrAB) two component system controls the expression of the DgkA PL recycling enzyme. The gene coding for phosphatidylserine decarboxylase, the last step in phosphatidylethanolamine synthesis is another gene in the PL synthesis pathway susceptible of stress response regulation. Indeed, psd appears in transcriptome studies of the σE envelope stress Sigma factor and of the CpxAR two component system. Interestingly, this gene is presumably in operon with mscM coding for a miniconductance mechanosensitive channel. In this study, we dissected the promoter region of the psd-mscM operon and studied its regulation by σE and CpxR. By artificial activation of σE and CpxRA stress response pathways, using GFP transcriptional fusion and western-blot analysis of Psd and MscM enzyme production, we showed that the operon is under the control of two distinct promoters. One is activated by σE, the second is activated by CpxRA and also responsible for basal expression of the operon. The fact that the phosphatidylethanolamine synthesis pathway is controlled by envelope stress responses at both its first and last steps might be important for adaptation of the membrane to envelope perturbations.
Collapse
Affiliation(s)
- Yasmine Hassoun
- LISM, Institut de Microbiologie de la Méditerranée, UMR 7255, CNRS and Aix-Marseille Université, Marseille, France
| | - Julia Bartoli
- LISM, Institut de Microbiologie de la Méditerranée, UMR 7255, CNRS and Aix-Marseille Université, Marseille, France
| | - Astrid Wahl
- LISM, Institut de Microbiologie de la Méditerranée, UMR 7255, CNRS and Aix-Marseille Université, Marseille, France
| | - Julie Pamela Viala
- LISM, Institut de Microbiologie de la Méditerranée, UMR 7255, CNRS and Aix-Marseille Université, Marseille, France
| | - Emmanuelle Bouveret
- SAMe Unit, UMR 2001, Microbiology Department, Pasteur Institute, Paris, France
| |
Collapse
|
15
|
(p)ppGpp/GTP and Malonyl-CoA Modulate Staphylococcus aureus Adaptation to FASII Antibiotics and Provide a Basis for Synergistic Bi-Therapy. mBio 2021; 12:mBio.03193-20. [PMID: 33531402 PMCID: PMC7858065 DOI: 10.1128/mbio.03193-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Staphylococcus aureus is a major human bacterial pathogen for which new inhibitors are urgently needed. Antibiotic development has centered on the fatty acid synthesis (FASII) pathway, which provides the building blocks for bacterial membrane phospholipids. Fatty acid biosynthesis (FASII) enzymes are considered valid targets for antimicrobial drug development against the human pathogen Staphylococcus aureus. However, incorporation of host fatty acids confers FASII antibiotic adaptation that compromises prospective treatments. S. aureus adapts to FASII inhibitors by first entering a nonreplicative latency period, followed by outgrowth. Here, we used transcriptional fusions and direct metabolite measurements to investigate the factors that dictate the duration of latency prior to outgrowth. We show that stringent response induction leads to repression of FASII and phospholipid synthesis genes. (p)ppGpp induction inhibits synthesis of malonyl-CoA, a molecule that derepresses FapR, a key regulator of FASII and phospholipid synthesis. Anti-FASII treatment also triggers transient expression of (p)ppGpp-regulated genes during the anti-FASII latency phase, with concomitant repression of FapR regulon expression. These effects are reversed upon outgrowth. GTP depletion, a known consequence of the stringent response, also occurs during FASII latency, and is proposed as the common signal linking these responses. We next showed that anti-FASII treatment shifts malonyl-CoA distribution between its interactants FapR and FabD, toward FapR, increasing expression of the phospholipid synthesis genes plsX and plsC during outgrowth. We conclude that components of the stringent response dictate malonyl-CoA availability in S. aureus FASII regulation, and contribute to latency prior to anti-FASII-adapted outgrowth. A combinatory approach, coupling a (p)ppGpp inducer and an anti-FASII, blocks S. aureus outgrowth, opening perspectives for bi-therapy treatment.
Collapse
|
16
|
Cronan JE. The Escherichia coli FadR transcription factor: Too much of a good thing? Mol Microbiol 2020; 115:1080-1085. [PMID: 33283913 DOI: 10.1111/mmi.14663] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 11/29/2020] [Accepted: 12/01/2020] [Indexed: 12/19/2022]
Abstract
Escherichia coli FadR is a transcription factor regulated by acyl-CoA thioester binding that optimizes fatty acid (FA) metabolism in response to environmental FAs. FadR represses the fad genes of FA degradation (β-oxidation) and activates the fab genes of FA synthesis thereby allowing E. coli to have its cake (acyl chains for phospholipid synthesis) and eat it (degrade acyl chains to acetyl-CoA). Acyl-CoA binding of FadR derepresses the transcription of the fad genes and cancels fab gene transcriptional activation. Activation of fab genes was thought restricted to the fabA and fabB genes of unsaturated FA synthesis, but FadR overproduction markedly increases yields of all FA acyl chains. Subsequently, almost all of the remaining fab genes were shown to be transcriptionally activated by FadR binding, but binding was very weak. Why are the low-affinity sites retained? What effects on cell physiology would result from their conversion to high-affinity sites (thereby mimicking FadR overproduction)? Investigations of E. coli cell size determinants showed that FA synthesis primarily determines E. coli cell size. Upon modest induction of FadR, cell size increases, but at the cost of growth rate and accumulation of intracellular membranes. Greater induction resulted in further growth rate decreases and abnormal cells. Hence, too much FadR is bad. FadR is extraordinarily conserved in γ-proteobacteria but has migrated. Mycobacterium tuberculosis encodes FadR orthologs one of which is functional in E. coli. Strikingly, the FadR theme of acyl-CoA-dependent transcriptional regulation is found in a different transcription factor family where two Bacillus species plus bacterial and archaeal thermophiles contain related proteins of similar function.
Collapse
Affiliation(s)
- John E Cronan
- Departments of Microbiology and Biochemistry, University of Illinois, Urbana, IL, USA
| |
Collapse
|
17
|
Pletnev P, Pupov D, Pshanichnaya L, Esyunina D, Petushkov I, Nesterchuk M, Osterman I, Rubtsova M, Mardanov A, Ravin N, Sergiev P, Kulbachinskiy A, Dontsova O. Rewiring of growth-dependent transcription regulation by a point mutation in region 1.1 of the housekeeping σ factor. Nucleic Acids Res 2020; 48:10802-10819. [PMID: 32997144 PMCID: PMC7641759 DOI: 10.1093/nar/gkaa798] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 09/09/2020] [Accepted: 09/12/2020] [Indexed: 01/24/2023] Open
Abstract
In bacteria, rapid adaptation to changing environmental conditions depends on the interplay between housekeeping and alternative σ factors, responsible for transcription of specific regulons by RNA polymerase (RNAP). In comparison with alternative σ factors, primary σs contain poorly conserved region 1.1, whose functions in transcription are only partially understood. We found that a single mutation in region 1.1 in Escherichia coli σ70 rewires transcription regulation during cell growth resulting in profound phenotypic changes. Despite its destabilizing effect on promoter complexes, this mutation increases the activity of rRNA promoters and also decreases RNAP sensitivity to the major regulator of stringent response DksA. Using total RNA sequencing combined with single-cell analysis of gene expression we showed that changes in region 1.1 disrupt the balance between the "greed" and "fear" strategies thus making the cells more susceptible to environmental threats and antibiotics. Our results reveal an unexpected role of σ region 1.1 in growth-dependent transcription regulation and suggest that changes in this region may facilitate rapid switching of RNAP properties in evolving bacterial populations.
Collapse
Affiliation(s)
- Philipp Pletnev
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
| | - Danil Pupov
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow,123182, Russia
| | | | - Daria Esyunina
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow,123182, Russia
| | - Ivan Petushkov
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow,123182, Russia
| | - Mikhail Nesterchuk
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143028, Russia
| | - Ilya Osterman
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia.,Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143028, Russia
| | - Maria Rubtsova
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia.,Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143028, Russia
| | - Andrey Mardanov
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Nikolai Ravin
- Institute of Bioengineering, Research Center of Biotechnology of the Russian Academy of Sciences, Moscow, Russia
| | - Petr Sergiev
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia.,Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143028, Russia.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia.,Institute of Functional Genomics, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Andrey Kulbachinskiy
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow,123182, Russia
| | - Olga Dontsova
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia.,Skolkovo Institute of Science and Technology, Skolkovo, Moscow Region 143028, Russia.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia
| |
Collapse
|
18
|
Quantification of guanosine triphosphate and tetraphosphate in plants and algae using stable isotope-labelled internal standards. Talanta 2020; 219:121261. [PMID: 32887152 DOI: 10.1016/j.talanta.2020.121261] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 06/03/2020] [Indexed: 12/20/2022]
Abstract
Guanosine tetraphosphate (G4P) and guanosine pentaphosphate (G5P) are signalling nucleotides found in bacteria and photosynthetic eukaryotes that are implicated in a wide-range of processes including stress acclimation, developmental transitions and growth control. Measurements of G4P/G5P levels are essential for studying the diverse roles of these nucleotides. However, G4P/G5P quantification is particularly challenging in plants and algae due to lower cellular concentrations, compartmentalization and high metabolic complexity. Despite recent advances the speed and accuracy of G4P quantification in plants and algae can still be improved. Here, we report a new approach for rapid and accurate G4P quantification which relies on the use of synthesized stable isotope-labelled as internal standards. We anticipate that this approach will accelerate research into the function of G4P signaling in plants, algae and other organisms.
Collapse
|
19
|
Swarbrick CMD, Nanson JD, Patterson EI, Forwood JK. Structure, function, and regulation of thioesterases. Prog Lipid Res 2020; 79:101036. [PMID: 32416211 DOI: 10.1016/j.plipres.2020.101036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/30/2020] [Accepted: 05/01/2020] [Indexed: 01/15/2023]
Abstract
Thioesterases are present in all living cells and perform a wide range of important biological functions by catalysing the cleavage of thioester bonds present in a diverse array of cellular substrates. Thioesterases are organised into 25 families based on their sequence conservation, tertiary and quaternary structure, active site configuration, and substrate specificity. Recent structural and functional characterisation of thioesterases has led to significant changes in our understanding of the regulatory mechanisms that govern enzyme activity and their respective cellular roles. The resulting dogma changes in thioesterase regulation include mechanistic insights into ATP and GDP-mediated regulation by oligomerisation, the role of new key regulatory regions, and new insights into a conserved quaternary structure within TE4 family members. Here we provide a current and comparative snapshot of our understanding of thioesterase structure, function, and regulation across the different thioesterase families.
Collapse
Affiliation(s)
| | - Jeffrey D Nanson
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience, Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Edward I Patterson
- Centre for Neglected Tropical Diseases, Departments of Vector Biology and Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Jade K Forwood
- School of Biomedical Sciences, Charles Sturt University, Boorooma Street, Wagga Wagga, New South Wales, Australia.
| |
Collapse
|
20
|
Yang HW, Yu M, Lee JH, Chatnaparat T, Zhao Y. The stringent response regulator (p) ppGpp mediates virulence gene expression and survival in Erwinia amylovora. BMC Genomics 2020; 21:261. [PMID: 32228459 PMCID: PMC7106674 DOI: 10.1186/s12864-020-6699-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 03/24/2020] [Indexed: 01/30/2023] Open
Abstract
Background The nucleotide second messengers, i.e., guanosine tetraphosphate and pentaphosphate [collectively referred to as (p) ppGpp], trigger the stringent response under nutrient starvation conditions and play an essential role in virulence in the fire blight pathogen Erwinia amylovora. Here, we present transcriptomic analyses to uncover the overall effect of (p) ppGpp-mediated stringent response in E. amylovora in the hrp-inducing minimal medium (HMM). Results In this study, we investigated the transcriptomic changes of the (p) ppGpp0 mutant under the type III secretion system (T3SS)-inducing condition using RNA-seq. A total of 1314 differentially expressed genes (DEGs) was uncovered, representing more than one third (36.8%) of all genes in the E. amylovora genome. Compared to the wild-type, the (p) ppGpp0 mutant showed down-regulation of genes involved in peptide ATP-binding cassette (ABC) transporters and virulence-related processes, including type III secretion system (T3SS), biofilm, and motility. Interestingly, in contrast to previous reports, the (p) ppGpp0 mutant showed up-regulation of amino acid biosynthesis genes, suggesting that it might be due to that these amino acid biosynthesis genes are indirectly regulated by (p) ppGpp in E. amylovora or represent specific culturing condition used. Furthermore, the (p) ppGpp0 mutant exhibited up-regulation of genes involved in translation, SOS response, DNA replication, chromosome segregation, as well as biosynthesis of nucleotide, fatty acid and lipid. Conclusion These findings suggested that in HMM environment, E. amylovora might use (p) ppGpp as a signal to activate virulence gene expression, and simultaneously mediate the balance between virulence and survival by negatively regulating DNA replication, translation, cell division, as well as biosynthesis of nucleotide, amino acid, fatty acid, and lipid. Therefore, (p) ppGpp could be a promising target for developing novel control measures to fight against this devastating disease of apples and pears.
Collapse
Affiliation(s)
- Ho-Wen Yang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Menghao Yu
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Jae Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Tiyakhon Chatnaparat
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, 1201 W. Gregory Dr, Urbana, IL, 61801, USA.
| |
Collapse
|
21
|
The Absence of (p)ppGpp Renders Initiation of Escherichia coli Chromosomal DNA Synthesis Independent of Growth Rates. mBio 2020; 11:mBio.03223-19. [PMID: 32156825 PMCID: PMC7064777 DOI: 10.1128/mbio.03223-19] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The initiation of Escherichia coli chromosomal DNA replication starts with the oligomerization of the DnaA protein at repeat sequences within the origin (ori) region. The amount of ori DNA per cell directly correlates with the growth rate. During fast growth, the cell generation time is shorter than the time required for complete DNA replication; therefore, overlapping rounds of chromosome replication are required. Under these circumstances, the ori region DNA abundance exceeds the DNA abundance in the termination (ter) region. Here, high ori/ter ratios are found to persist in (p)ppGpp-deficient [(p)ppGpp0] cells over a wide range of balanced exponential growth rates determined by medium composition. Evidently, (p)ppGpp is necessary to maintain the usual correlation of slow DNA replication initiation with a low growth rate. Conversely, ori/ter ratios are lowered when cell growth is slowed by incrementally increasing even low constitutive basal levels of (p)ppGpp without stress, as if (p)ppGpp alone is sufficient for this response. There are several previous reports of (p)ppGpp inhibition of chromosomal DNA synthesis initiation that occurs with very high levels of (p)ppGpp that stop growth, as during the stringent starvation response or during serine hydroxamate treatment. This work suggests that low physiological levels of (p)ppGpp have significant functions in growing cells without stress through a mechanism involving negative supercoiling, which is likely mediated by (p)ppGpp regulation of DNA gyrase.IMPORTANCE Bacterial cells regulate their own chromosomal DNA synthesis and cell division depending on the growth conditions, producing more DNA when growing in nutritionally rich media than in poor media (i.e., human gut versus water reservoir). The accumulation of the nucleotide analog (p)ppGpp is usually viewed as serving to warn cells of impending peril due to otherwise lethal sources of stress, which stops growth and inhibits DNA, RNA, and protein synthesis. This work importantly finds that small physiological changes in (p)ppGpp basal levels associated with slow balanced exponential growth incrementally inhibit the intricate process of initiation of chromosomal DNA synthesis. Without (p)ppGpp, initiations mimic the high rates present during fast growth. Here, we report that the effect of (p)ppGpp may be due to the regulation of the expression of gyrase, an important enzyme for the replication of DNA that is a current target of several antibiotics.
Collapse
|
22
|
Zhao L, Lu Y, Yang J, Fang Y, Zhu L, Ding Z, Wang C, Ma W, Hu X, Wang X. Expression regulation of multiple key genes to improve L-threonine in Escherichia coli. Microb Cell Fact 2020; 19:46. [PMID: 32093713 PMCID: PMC7041290 DOI: 10.1186/s12934-020-01312-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 02/18/2020] [Indexed: 11/28/2022] Open
Abstract
Background Escherichia coli is an important strain for l-threonine production. Genetic switch is a ubiquitous regulatory tool for gene expression in prokaryotic cells. To sense and regulate intracellular or extracellular chemicals, bacteria evolve a variety of transcription factors. The key enzymes required for l-threonine biosynthesis in E. coli are encoded by the thr operon. The thr operon could coordinate expression of these genes when l-threonine is in short supply in the cell. Results The thrL leader regulatory elements were applied to regulate the expression of genes iclR, arcA, cpxR, gadE, fadR and pykF, while the threonine-activating promoters PcysH, PcysJ and PcysD were applied to regulate the expression of gene aspC, resulting in the increase of l-threonine production in an l-threonine producing E. coli strain TWF001. Firstly, different parts of the regulator thrL were inserted in the iclR regulator region in TWF001, and the best resulting strain TWF063 produced 16.34 g l-threonine from 40 g glucose after 30 h cultivation. Secondly, the gene aspC following different threonine-activating promoters was inserted into the chromosome of TWF063, and the best resulting strain TWF066 produced 17.56 g l-threonine from 40 g glucose after 30 h cultivation. Thirdly, the effect of expression regulation of arcA, cpxR, gadE, pykF and fadR was individually investigated on l-threonine production in TWF001. Finally, using TWF066 as the starting strain, the expression of genes arcA, cpxR, gadE, pykF and fadR was regulated individually or in combination to obtain the best strain for l-threonine production. The resulting strain TWF083, in which the expression of seven genes (iclR, aspC, arcA, cpxR, gadE, pykF, fadR and aspC) was regulated, produced 18.76 g l-threonine from 30 g glucose, 26.50 g l-threonine from 40 g glucose, or 26.93 g l-threonine from 50 g glucose after 30 h cultivation. In 48 h fed-batch fermentation, TWF083 could produce 116.62 g/L l‐threonine with a yield of 0.486 g/g glucose and productivity of 2.43 g/L/h. Conclusion The genetic engineering through the expression regulation of key genes is a better strategy than simple deletion of these genes to improve l-threonine production in E. coli. This strategy has little effect on the intracellular metabolism in the early stage of the growth but could increase l-threonine biosynthesis in the late stage.
Collapse
Affiliation(s)
- Lei Zhao
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Ying Lu
- Nanjing Customs District P. R. China, Wuxi, 214122, China
| | - Jun Yang
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Yu Fang
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Lifei Zhu
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Zhixiang Ding
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Chenhui Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Wenjian Ma
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Xiaoqing Hu
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China.,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi, 214122, China. .,International Joint Laboratory on Food Safety, Jiangnan University, Wuxi, 214122, China. .,Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, China.
| |
Collapse
|
23
|
Quantitative Connection between Cell Size and Growth Rate by Phospholipid Metabolism. Cells 2020; 9:cells9020391. [PMID: 32046235 PMCID: PMC7072380 DOI: 10.3390/cells9020391] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 02/04/2020] [Indexed: 11/16/2022] Open
Abstract
The processes involved in cell growth are extremely complicated even for a single cell organism such as Escherichia coli, while the relationship between growth rate and cell size is simple. We aimed to reveal the systematic link between them from the aspect of the genome-scale metabolic network. Since the growth rate reflects metabolic rates of bacteria and the cell size relates to phospholipid synthesis, a part of bacterial metabolic networks, we calculated the cell length from the cardiolipin synthesis rate, where the cardiolipin synthesis reaction is able to represent the phospholipid metabolism of Escherichia coli in the exponential growth phase. Combined with the flux balance analysis, it enables us to predict cell length and to examine the quantitative relationship between cell length and growth rate. By simulating bacteria growing in various nutrient media with the flux balance analysis and calculating the corresponding cell length, we found that the increase of the synthesis rate of phospholipid, the cell width, and the protein fraction in membranes caused the increase of cell length with growth rate. Different tendencies of phospholipid synthesis rate changing with growth rate result in different relationships between cell length and growth rate. The effects of gene deletions on cell size and growth rate are also examined. Knocking out the genes, such as Δ tktA, Δ tktB, Δ yqaB, Δ pgm, and Δ cysQ, affects growth rate largely while affecting cell length slightly. Results of this method are in good agreement with experiments.
Collapse
|
24
|
Yang SP, Xie J, Cheng Y, Zhang Z, Zhao Y, Qian YF. Response of Shewanella putrefaciens to low temperature regulated by membrane fluidity and fatty acid metabolism. Lebensm Wiss Technol 2020. [DOI: 10.1016/j.lwt.2019.108638] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
25
|
RSH enzyme diversity for (p)ppGpp metabolism in Phaeodactylum tricornutum and other diatoms. Sci Rep 2019; 9:17682. [PMID: 31776430 PMCID: PMC6881373 DOI: 10.1038/s41598-019-54207-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 11/05/2019] [Indexed: 12/28/2022] Open
Abstract
The nucleotides guanosine tetraphosphate and pentaphosphate (together known as (p)ppGpp or magic spot) are produced in plant plastids from GDP/GTP and ATP by RelA-SpoT homologue (RSH) enzymes. In the model plant Arabidopsis (p)ppGpp regulates chloroplast transcription and translation to affect growth, and is also implicated in acclimation to stress. However, little is known about (p)ppGpp metabolism or its evolution in other photosynthetic eukaryotes. Here we studied (p)ppGpp metabolism in the marine diatom Phaeodactylum tricornutum. We identified three expressed RSH genes in the P. tricornutum genome, and determined the enzymatic activity of the corresponding enzymes by heterologous expression in bacteria. We showed that two P. tricornutum RSH are (p)ppGpp synthetases, despite substitution of a residue within the active site believed critical for activity, and that the third RSH is a bifunctional (p)ppGpp synthetase and hydrolase, the first of its kind demonstrated in a photosynthetic eukaryote. A broad phylogenetic analysis then showed that diatom RSH belong to novel algal RSH clades. Together our work significantly expands the horizons of (p)ppGpp signalling in the photosynthetic eukaryotes by demonstrating an unexpected functional, structural and evolutionary diversity in RSH enzymes from organisms with plastids derived from red algae.
Collapse
|
26
|
Sun Y, Meng Q, Zhang Y, Gao H. Derepression of bkd by the FadR loss dictates elevated production of BCFAs and isoleucine starvation. Biochim Biophys Acta Mol Cell Biol Lipids 2019; 1865:158577. [PMID: 31759173 DOI: 10.1016/j.bbalip.2019.158577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/13/2019] [Indexed: 12/21/2022]
Abstract
In many γ-proteobacteria, FadR is recognized as a global transcriptional regulator: in addition to being the most prominent regulator for FA biosynthesis and degradation, the protein also mediates expression of many genes in diverse biological processes. In Shewanella oneidensis, a bacterium renowned for its respiratory versatility, FadR directly controls only a few genes. However, the FadR loss substantially increases BCFA contents and impairs growth. In this study, we showed that FadR is required to activate a number of important FA biosynthesis genes, including fabA, fabB, and fabH1. Although most of these genes are controlled by FadR in a direct manner, they are not critically responsible for the phenotypes resulting from the FadR depletion. Subsequent investigations identified BKD encoded by the bkd operon as the critical factor for enhanced BCFA production. In the absence of FadR, the bkd operon is derepressed, resulting in elevated conversion of 3MOP to 3-methylbutanoyl-CoA, one of the direct substrates for BCFA synthesis. We further showed that the growth defect of the fadR mutant is due to BCAA shortage, a scenario also attributable to excessive BKD: 3MOP, the common substrate for both BCFA and BCAA, is disproportionately used for BCFA synthesis, leading to reduced production of BCAA. Collectively, our findings reveal that the S. oneidensis FadR regulon is surely larger than previously proposed and a new mechanism by which FadR impacts bacterial physiology.
Collapse
Affiliation(s)
- Yijuan Sun
- Institute of Microbiology College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Qiu Meng
- Institute of Microbiology College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China; College of Biotechnology and Bioengineering, Zhejiang University of Technology, 18 Chaowang Rd, Hangzhou, 310014, Zhejiang, China
| | - Yongting Zhang
- Institute of Microbiology College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Haichun Gao
- Institute of Microbiology College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China.
| |
Collapse
|
27
|
Enhanced Production of Fatty Acid Ethyl Ester with Engineered fabHDG Operon in Escherichia coli. Microorganisms 2019; 7:microorganisms7110552. [PMID: 31717929 PMCID: PMC6920873 DOI: 10.3390/microorganisms7110552] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Revised: 10/23/2019] [Accepted: 11/05/2019] [Indexed: 12/16/2022] Open
Abstract
Biodiesel, or fatty acid ethyl ester (FAEE), is an environmentally safe, next-generation biofuel. Conventionally, FAEE is produced by the conversion of oil/fats, obtained from plants, animals, and microorganisms, by transesterification. Recently, metabolic engineering of bacteria for ready-to-use biodiesel was developed. In Escherichia coli, it is produced by fatty acyl-carrier proteins and ethanol, with the help of thioesterase (TesB) and wax synthase (WS) enzymes. One of the foremost barriers in microbial FAEE production is the feedback inhibition of the fatty acid (FA) operon (fabHDG). Here, we studied the effect of biodiesel biosynthesis in E. coli with an engineered fabHDG operon. With a basic FAEE producing BD1 strain harboring tes and ws genes, biodiesel of 32 mg/L were produced. Optimal FAEE biosynthesis was achieved in the BD2 strain that carries an overexpressed operon (fabH, fabD, and fabG genes) and achieved up to 1291 mg/L of biodiesel, a 40-fold rise compared to the BD1 strain. The composition of FAEE obtained from the BD2 strain was 65% (C10:C2, decanoic acid ethyl ester) and 35% (C12:C2, dodecanoic acid ethyl ester). Our findings indicate that overexpression of the native FA operon, along with FAEE biosynthesis enzymes, improved biodiesel biosynthesis in E. coli.
Collapse
|
28
|
Bez C, Javvadi SG, Bertani I, Devescovi G, Guarnaccia C, Studholme DJ, Geller AM, Levy A, Venturi V. AzeR, a transcriptional regulator that responds to azelaic acid in Pseudomonas nitroreducens. MICROBIOLOGY-SGM 2019; 166:73-84. [PMID: 31621557 PMCID: PMC7398562 DOI: 10.1099/mic.0.000865] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Azelaic acid is a dicarboxylic acid that has recently been shown to play a role in plant-bacteria signalling and also occurs naturally in several cereals. Several bacteria have been reported to be able to utilize azelaic acid as a unique source of carbon and energy, including Pseudomonas nitroreducens. In this study, we utilize P. nitroreducens as a model organism to study bacterial degradation of and response to azelaic acid. We report genetic evidence of azelaic acid degradation and the identification of a transcriptional regulator that responds to azelaic acid in P. nitroreducens DSM 9128. Three mutants possessing transposons in genes of an acyl-CoA ligase, an acyl-CoA dehydrogenase and an isocitrate lyase display a deficient ability in growing in azelaic acid. Studies on transcriptional regulation of these genes resulted in the identification of an IclR family repressor that we designated as AzeR, which specifically responds to azelaic acid. A bioinformatics survey reveals that AzeR is confined to a few proteobacterial genera that are likely to be able to degrade and utilize azelaic acid as the sole source of carbon and energy.
Collapse
Affiliation(s)
- Cristina Bez
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Sree Gowrinadh Javvadi
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Iris Bertani
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Giulia Devescovi
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | - Corrado Guarnaccia
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| | | | - Alexander M Geller
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, POB 12 Rehovot 761001, Israel
| | - Asaf Levy
- Department of Plant Pathology and Microbiology, The Robert H. Smith Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, POB 12 Rehovot 761001, Israel
| | - Vittorio Venturi
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy
| |
Collapse
|
29
|
A Novel Gene Contributing to the Initiation of Fatty Acid Biosynthesis in Escherichia coli. J Bacteriol 2019; 201:JB.00354-19. [PMID: 31331975 DOI: 10.1128/jb.00354-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Accepted: 07/08/2019] [Indexed: 11/20/2022] Open
Abstract
Type II fatty acid biosynthesis in bacteria can be broadly classified into the initiation and elongation phases. The biochemical functions defining each step in the two phases have been studied in vitro Among the β-ketoacyl-acyl carrier protein (ACP) synthases, FabH catalyzes the initiation reaction, while FabB and FabF, which primarily catalyze the elongation reaction, can also drive initiation as side reactions. A role for FabB and FabF in the initiation of fatty acid biosynthesis would be supported by the viability of the ΔfabH mutant. In this study, we show that the ΔfabH and ΔyiiD mutations were synthetically lethal and that ΔfabH ΔrelA ΔspoT and ΔfabH ΔdksA synthetic lethality was rescued by the heterologous expression of yiiD In the ΔfabH mutant, the expression of yiiD was positively regulated by (p)ppGpp. The growth defect, reduced cell size, and altered fatty acid profile of the ΔfabH mutant and the growth defect of the ΔfabH ΔfabF fabB15(Ts) mutant in oleate- and palmitate-supplemented medium at 42°C were rescued by the expression of yiiD from a multicopy plasmid. Together, these results indicate that the yiiD-encoded function supported initiation of fatty acid biosynthesis in the absence of FabH. We have renamed yiiD as fabY IMPORTANCE Fatty acid biosynthesis is an essential process conserved across life forms. β-Ketoacyl-ACP synthases are essential for fatty acid biosynthesis. FabH is a β-ketoacyl-ACP synthase that contributes to the initiation of fatty acid biosynthesis in Escherichia coli In this study, we present genetic and biochemical evidence that the yiiD (renamed fabY)-encoded function contributes to the biosynthesis of fatty acid in the absence of FabH activity and that under these conditions, the expression of FabY was regulated by the stringent response factors (p)ppGpp and DksA. Combined inactivation of FabH and FabY resulted in growth arrest, possibly due to the loss of fatty acid biosynthesis. A molecule(s) that inhibits the two activities can be an effective microbicide.
Collapse
|
30
|
Izzo L, Matrella S, Mella M, Benvenuto G, Vigliotta G. Escherichia coli as a Model for the Description of the Antimicrobial Mechanism of a Cationic Polymer Surface: Cellular Target and Bacterial Contrast Response. ACS APPLIED MATERIALS & INTERFACES 2019; 11:15332-15343. [PMID: 30950609 DOI: 10.1021/acsami.9b02903] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this study, we use Escherichia coli as a model to investigate the antimicrobial mechanism of a film made of a copolymer based on monomethylether poly(ethylene glycol), methyl methacrylate, and 2-dimethyl(aminoethyl) methacrylate, whose surface is active towards Gram-negative and Gram-positive bacteria. The polymer contains not quaternized amino groups that can generate a charged surface by protonation when in contact with water. For this purpose, we adopted a dual strategy based on the analysis of cell damage caused by contact with the polymer surface and on the evaluation of the cell response to the surface toxic action. The lithic effect on the protoplasts of E. coli showed that the polymer surface can affect the structure of cytoplasmic membranes, while assays of calcein leakage from large unilamellar vesicles at different phospholipid compositions indicated that action on membranes does not need a functionally active cell. On the other hand, the significant increase in sensitivity to actinomycin D demonstrates that the polymer interferes also with the structure of the outer membrane, modifying its permeability. The study on gene expression, based on the analysis of the transcripts in a temporal window where the contact with the polymer is not lethal and the damage is reversible, showed that some key genes of the synthesis and maintenance of the outer membrane structure ( fabR, fadR, fabA, waaA, waaC, kdsA, pldA, and pagP), as well as regulators of cellular response to oxidative stress ( soxS), are more expressed when bacteria are exposed to the polymer surface. All together these results identified the outer membrane as the main cellular target of the antimicrobial surface and indicated a specific cellular response to damage, providing more information on the antimicrobial mechanism. In this perspective, data reported here could play a pivotal role in a microbial growth control strategy based not only on the structural improvements of the materials but also on the possibility of intervening on the cellular pathways involved in the contrast reaction to these and other polymers with similar mechanisms.
Collapse
Affiliation(s)
- Lorella Izzo
- Dipartimento di Biotecnologie e Scienze della Vita , Università degli Studi dell'Insubria , Via J.H. Dunant, 3 , 21100 Varese , Italy
| | - Simona Matrella
- Dipartimento di Chimica e Biologia "A. Zambelli" , Università degli Studi di Salerno , Via Giovanni Paolo II, 132 , 84084 Fisciano , Salerno , Italy
| | - Massimo Mella
- Dipartimento di Scienza ed Alta Tecnologia , Università degli Studi dell'Insubria , via Valleggio, 11 , 22100 Como , Italy
| | | | - Giovanni Vigliotta
- Dipartimento di Chimica e Biologia "A. Zambelli" , Università degli Studi di Salerno , Via Giovanni Paolo II, 132 , 84084 Fisciano , Salerno , Italy
| |
Collapse
|
31
|
Yang J, Fang Y, Wang J, Wang C, Zhao L, Wang X. Deletion of regulator-encoding genes fadR, fabR and iclR to increase L-threonine production in Escherichia coli. Appl Microbiol Biotechnol 2019; 103:4549-4564. [DOI: 10.1007/s00253-019-09818-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2019] [Revised: 03/19/2019] [Accepted: 03/31/2019] [Indexed: 12/25/2022]
|
32
|
Microbial Production of Fatty Acid via Metabolic Engineering and Synthetic Biology. BIOTECHNOL BIOPROC E 2019. [DOI: 10.1007/s12257-018-0374-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
33
|
Thomanek N, Arends J, Lindemann C, Barkovits K, Meyer HE, Marcus K, Narberhaus F. Intricate Crosstalk Between Lipopolysaccharide, Phospholipid and Fatty Acid Metabolism in Escherichia coli Modulates Proteolysis of LpxC. Front Microbiol 2019; 9:3285. [PMID: 30692974 PMCID: PMC6339880 DOI: 10.3389/fmicb.2018.03285] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 12/17/2018] [Indexed: 12/26/2022] Open
Abstract
Lipopolysaccharides (LPS) in the outer membrane of Gram-negative bacteria provide the first line of defense against antibiotics and other harmful compounds. LPS biosynthesis critically depends on LpxC catalyzing the first committed enzyme in this process. In Escherichia coli, the cellular concentration of LpxC is adjusted in a growth rate-dependent manner by the FtsH protease making sure that LPS biosynthesis is coordinated with the cellular demand. As a result, LpxC is stable in fast-growing cells and prone to degradation in slow-growing cells. One of the factors involved in this process is the alarmone guanosine tetraphosphate (ppGpp) but previous studies suggested the involvement of yet unknown factors in LpxC degradation. We established a quantitative proteomics approach aiming at the identification of proteins that are associated with LpxC and/or FtsH at high or low growth rates. The identification of known LpxC and FtsH interactors validated our approach. A number of proteins involved in fatty acid biosynthesis and degradation, including the central regulator FadR, were found in the LpxC and/or FtsH interactomes. Another protein associated with LpxC and FtsH was WaaH, a LPS-modifying enzyme. When overproduced, several members of the LpxC/FtsH interactomes were able to modulate LpxC proteolysis. Our results go beyond the previously established link between LPS and phospholipid biosynthesis and uncover a far-reaching network that controls LPS production by involving multiple enzymes in fatty acid metabolism, phospholipid biosynthesis and LPS modification.
Collapse
Affiliation(s)
- Nikolas Thomanek
- Medical Proteome Center, Ruhr University Bochum, Bochum, Germany
| | - Jan Arends
- Microbial Biology, Ruhr University Bochum, Bochum, Germany
| | | | | | - Helmut E Meyer
- Medical Proteome Center, Ruhr University Bochum, Bochum, Germany.,Biomedical Research, Leibniz-Institut für Analytische Wissenschaften - ISAS - e. V., Dortmund, Germany
| | - Katrin Marcus
- Medical Proteome Center, Ruhr University Bochum, Bochum, Germany
| | | |
Collapse
|
34
|
Lensmire JM, Pratt ZL, Wong ACL, Kaspar CW. Phosphate and carbohydrate facilitate the formation of filamentous Salmonella enterica during osmotic stress. MICROBIOLOGY-SGM 2018; 164:1503-1513. [PMID: 30325297 DOI: 10.1099/mic.0.000731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Salmonella enterica is a human pathogen that can produce filamentous cells in response to environmental stress. The molecular mediators and biosynthetic pathways that contribute to the formation of filamentous cells (>10 µm in length) during osmotic stress are mostly unknown. The comparison of filamentous and non-filamentous cells in this study was aided by the use of a filtration step to separate cell types. Osmotic stress caused an efflux of phosphate from cells, and the addition of phosphate and a carbohydrate to Luria broth with 7 % NaCl (LB-7NaCl) significantly increased the proportion of filamentous cells in the population (58 %). In addition to direct measurements of intracellular and extracellular phosphate concentrations, the relative abundance of the iraP transcript that is induced by phosphate limitation was monitored. Non-filamentous cells had a greater relative abundance of iraP transcript than filamentous cells. IraP also affects the stability of RpoS, which regulates the general stress regulon, and was detected in non-filamentous cells but not filamentous cells. Markers of metabolic pathways for the production of acetyl-CoA (pflB, encoding for pyruvate formate lyase) and fatty acids (fabH) that are essential to membrane biosynthesis were found in greater abundance in filamentous cells than non-filamentous cells. There were no differences in the DNA, protein and biomass levels in filamentous and non-filamentous cells after 48 h of incubation, although the filamentous cells produced significantly (P<0.05) more acetate. This study found that phosphate and carbohydrate enhanced the formation of filamentous cells during osmotic stress, and there were differences in key regulatory elements and markers of metabolic pathways in filamentous and non-filamentous S. enterica.
Collapse
Affiliation(s)
- Joshua M Lensmire
- 1Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, USA
| | | | - Amy C L Wong
- 1Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, USA.,3Food Research Institute, University of Wisconsin - Madison, Madison, WI, USA
| | - Charles W Kaspar
- 3Food Research Institute, University of Wisconsin - Madison, Madison, WI, USA.,1Department of Bacteriology, University of Wisconsin - Madison, Madison, WI, USA
| |
Collapse
|
35
|
Siroli L, Braschi G, de Jong A, Kok J, Patrignani F, Lanciotti R. Transcriptomic approach and membrane fatty acid analysis to study the response mechanisms of Escherichia coli to thyme essential oil, carvacrol, 2-(E)-hexanal and citral exposure. J Appl Microbiol 2018; 125:1308-1320. [PMID: 30028070 DOI: 10.1111/jam.14048] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 06/21/2018] [Accepted: 07/15/2018] [Indexed: 12/18/2022]
Abstract
AIMS The application of essential oils (EOs) and their components as food preservatives is promising but requires a deeper understanding of their mechanisms of action. This study aims to evaluate the effects of thyme EO, carvacrol, citral and 2-(E)-hexenal, on whole-genome gene expression (the transcriptome), as well as the fatty acid (FA) composition of the cell membranes of Escherichia coli K12. METHODS AND RESULTS Therefore, we studied the response against 1 h of exposure to sublethal concentrations of natural antimicrobials, of exponentially growing E. coli K12, using DNA microarray technology and a gas chromatographic method. The results show that treatment with a sublethal concentration of the antimicrobials strongly affects global gene expression in E. coli for all antimicrobials used. Major changes in the expression of genes involved in metabolic pathways as well as in FA biosynthesis and protection against oxidative stress were evidenced. Moreover, the sublethal treatments resulted in increased levels of unsaturated and cyclic FAs as well as an increase in the chain length compared to the controls. CONCLUSIONS The down-regulation of genes involved in aerobic metabolism indicates a shift from respiration to fermentative growth. Moreover, the results obtained suggest that the cytoplasmic membrane of E. coli is the major cellular target of EOs and their components. In addition, the key role of membrane unsaturated FAs in the response mechanisms of E. coli to natural antimicrobials has been confirmed in this study. SIGNIFICANCE AND IMPACT OF THE STUDY The transcriptomic data obtained signify a further step to understand the mechanisms of action of natural antimicrobials also when sublethal concentrations and short-term exposure. In addition, this research goes in deep correlating the transcriptomic modification with the changes in E. coli FA composition of cell membrane identified as the main target of the natural antimicrobials.
Collapse
Affiliation(s)
- L Siroli
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Campus of Food Science, Cesena, Italy.,Interdipartimental Centre for Industrial Research-CIRI-AGRIFOOD, Alma Mater Studiorum, University of Bologna, Cesena (FC), Italy
| | - G Braschi
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Campus of Food Science, Cesena, Italy
| | - A de Jong
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, AG Groningen, The Netherlands
| | - J Kok
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, AG Groningen, The Netherlands
| | - F Patrignani
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Campus of Food Science, Cesena, Italy.,Interdipartimental Centre for Industrial Research-CIRI-AGRIFOOD, Alma Mater Studiorum, University of Bologna, Cesena (FC), Italy
| | - R Lanciotti
- Department of Agricultural and Food Sciences, Alma Mater Studiorum, University of Bologna, Campus of Food Science, Cesena, Italy.,Interdipartimental Centre for Industrial Research-CIRI-AGRIFOOD, Alma Mater Studiorum, University of Bologna, Cesena (FC), Italy
| |
Collapse
|
36
|
Linking glucose metabolism to the stringent response through the PTS. Proc Natl Acad Sci U S A 2018; 115:7454-7455. [PMID: 29970419 DOI: 10.1073/pnas.1809265115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
37
|
fabH deletion increases DHA production in Escherichia coli expressing Pfa genes. Microb Cell Fact 2018; 17:88. [PMID: 29884177 PMCID: PMC5992819 DOI: 10.1186/s12934-018-0928-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/11/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Some marine bacteria, such as Moritella marina, produce the nutraceutical docosahexaenoic acid (DHA) thanks to a specific enzymatic complex called Pfa synthase. Escherichia coli heterologously expressing the pfa gene cluster from M. marina also produces DHA. The aim of this study was to find genetic or metabolic conditions to increase DHA production in E. coli. RESULTS First, we analysed the effect of the antibiotic cerulenin, showing that DHA production increased twofold. Then, we tested a series of single gene knockout mutations affecting fatty acid biosynthesis, in order to optimize the synthesis of DHA. The most effective mutant, fabH, showed a threefold increase compared to wild type strain. The combination of cerulenin inhibition and fabH deletion rendered a 6.5-fold improvement compared to control strain. Both strategies seem to have the same mechanism of action, in which fatty acid synthesis via the canonical pathway (fab pathway) is affected in its first catalytic step, which allows the substrates to be used by the heterologous pathway to synthesize DHA. CONCLUSIONS DHA-producing E. coli strain that carries a fabH gene deletion boosts DHA production by tuning down the competing canonical biosynthesis pathway. Our approach can be used for optimization of DHA production in different organisms.
Collapse
|
38
|
Srisukchayakul P, Charalampopoulos D, Karatzas KA. Study on the effect of citric acid adaptation toward the subsequent survival of Lactobacillus plantarum NCIMB 8826 in low pH fruit juices during refrigerated storage. Food Res Int 2018; 111:198-204. [PMID: 30007676 DOI: 10.1016/j.foodres.2018.05.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 05/05/2018] [Accepted: 05/08/2018] [Indexed: 01/16/2023]
Abstract
Pre-treatment of stationary phase cells of Lactobacillus plantarum NCMIB 8826 with citric acid (pH 3 to 6) for a short period of time significantly improved subsequent cell survival in several highly acidic fruit juices namely cranberry (pH 2.7), pomegranate (pH 3.5), and lemon & lime juices (pH 2.8). Although the mechanism for this adaptation is still unclear, the analysis of the cellular fatty acid content of acid adapted cells and the reverse transcription polymerase chain reaction (RT-PCR) showed a significant increase (by ~1.7 fold) of the cellular cyclopropane fatty acid, cis-11,12-methylene octadecanoic acid (C19:0cyclow7c) and a significant upregulation (~12 fold) of cyclopropane synthase (cfa) were observed, respectively, during acid adaptation. It is likely that these changes led to a decrease in membrane fluidity and to lower membrane permeability, which prevents the cells from proton influx during storage in these low pH fruit juices.
Collapse
Affiliation(s)
- Pornpoj Srisukchayakul
- Department of Food and Nutritional Sciences, University of Reading, PO Box 226, Whiteknights, Reading RG6 6AP, United Kingdom
| | - Dimitris Charalampopoulos
- Department of Food and Nutritional Sciences, University of Reading, PO Box 226, Whiteknights, Reading RG6 6AP, United Kingdom
| | - Kimon Andreas Karatzas
- Department of Food and Nutritional Sciences, University of Reading, PO Box 226, Whiteknights, Reading RG6 6AP, United Kingdom; CINN (Centre for Integrative Neuroscience and Neurodynamics), University of Reading, Whiteknights, Reading RG6 6BE, United Kingdom.
| |
Collapse
|
39
|
Santos-Merino M, Garcillán-Barcia MP, de la Cruz F. Engineering the fatty acid synthesis pathway in Synechococcus elongatus PCC 7942 improves omega-3 fatty acid production. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:239. [PMID: 30202434 PMCID: PMC6123915 DOI: 10.1186/s13068-018-1243-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/27/2018] [Indexed: 05/09/2023]
Abstract
BACKGROUND The microbial production of fatty acids has received great attention in the last few years as feedstock for the production of renewable energy. The main advantage of using cyanobacteria over other organisms is their ability to capture energy from sunlight and to transform CO2 into products of interest by photosynthesis, such as fatty acids. Fatty acid synthesis is a ubiquitous and well-characterized pathway in most bacteria. However, the activity of the enzymes involved in this pathway in cyanobacteria remains poorly explored. RESULTS To characterize the function of some enzymes involved in the saturated fatty acid synthesis in cyanobacteria, we genetically engineered Synechococcus elongatus PCC 7942 by overexpressing or deleting genes encoding enzymes of the fatty acid synthase system and tested the lipid profile of the mutants. These modifications were in turn used to improve alpha-linolenic acid production in this cyanobacterium. The mutant resulting from fabF overexpression and fadD deletion, combined with the overexpression of desA and desB desaturase genes from Synechococcus sp. PCC 7002, produced the highest levels of this omega-3 fatty acid. CONCLUSIONS The fatty acid composition of S. elongatus PCC 7942 can be significantly modified by genetically engineering the expression of genes coding for the enzymes involved in the first reactions of fatty acid synthesis pathway. Variations in fatty acid composition of S. elongatus PCC 7942 mutants did not follow the pattern observed in Escherichia coli derivatives. Some of these modifications can be used to improve omega-3 fatty acid production. This work provides new insights into the saturated fatty acid synthesis pathway and new strategies that might be used to manipulate the fatty acid content of cyanobacteria.
Collapse
Affiliation(s)
- María Santos-Merino
- Instituto de Biomedicina y Biotecnología de Cantabria (Universidad de Cantabria—Consejo Superior de Investigaciones Científicas), Santander, Cantabria Spain
| | - M. Pilar Garcillán-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria (Universidad de Cantabria—Consejo Superior de Investigaciones Científicas), Santander, Cantabria Spain
| | - Fernando de la Cruz
- Instituto de Biomedicina y Biotecnología de Cantabria (Universidad de Cantabria—Consejo Superior de Investigaciones Científicas), Santander, Cantabria Spain
| |
Collapse
|
40
|
Gao R, Li D, Lin Y, Lin J, Xia X, Wang H, Bi L, Zhu J, Hassan B, Wang S, Feng Y. Structural and Functional Characterization of the FadR Regulatory Protein from Vibrio alginolyticus. Front Cell Infect Microbiol 2017; 7:513. [PMID: 29312893 PMCID: PMC5733061 DOI: 10.3389/fcimb.2017.00513] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/29/2017] [Indexed: 02/03/2023] Open
Abstract
The structure of Vibrio cholerae FadR (VcFadR) complexed with the ligand oleoyl-CoA suggests an additional ligand-binding site. However, the fatty acid metabolism and its regulation is poorly addressed in Vibrio alginolyticus, a species closely-related to V. cholerae. Here, we show crystal structures of V. alginolyticus FadR (ValFadR) alone and its complex with the palmitoyl-CoA, a long-chain fatty acyl ligand different from the oleoyl-CoA occupied by VcFadR. Structural comparison indicates that both VcFadR and ValFadR consistently have an additional ligand-binding site (called site 2), which leads to more dramatic conformational-change of DNA-binding domain than that of the E. coli FadR (EcFadR). Isothermal titration calorimetry (ITC) analyses defines that the ligand-binding pattern of ValFadR (2:1) is distinct from that of EcFadR (1:1). Together with surface plasmon resonance (SPR), electrophoresis mobility shift assay (EMSA) demonstrates that ValFadR binds fabA, an important gene of unsaturated fatty acid (UFA) synthesis. The removal of fadR from V. cholerae attenuates fabA transcription and results in the unbalance of UFA/SFA incorporated into membrane phospholipids. Genetic complementation of the mutant version of fadR (Δ42, 136-177) lacking site 2 cannot restore the defective phenotypes of ΔfadR while the wild-type fadR gene and addition of exogenous oleate can restore them. Mice experiments reveals that VcFadR and its site 2 have roles in bacterial colonizing. Together, the results might represent an additional example that illustrates the Vibrio FadR-mediated lipid regulation and its role in pathogenesis.
Collapse
Affiliation(s)
- Rongsui Gao
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, China
| | - Defeng Li
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yuan Lin
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jingxia Lin
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaoyun Xia
- Department of Microbiology, Nanjing Agricultural University, Nanjing, China
| | - Hui Wang
- Department of Microbiology, Nanjing Agricultural University, Nanjing, China
| | - Lijun Bi
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jun Zhu
- Department of Microbiology, Nanjing Agricultural University, Nanjing, China.,Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Bachar Hassan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Shihua Wang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Youjun Feng
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
41
|
Sivapragasam S, Deochand DK, Meariman JK, Grove A. The Stringent Response Induced by Phosphate Limitation Promotes Purine Salvage in Agrobacterium fabrum. Biochemistry 2017; 56:5831-5843. [DOI: 10.1021/acs.biochem.7b00844] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Smitha Sivapragasam
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Dinesh K. Deochand
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Jacob K. Meariman
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Anne Grove
- Department of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| |
Collapse
|
42
|
Vadia S, Tse JL, Lucena R, Yang Z, Kellogg DR, Wang JD, Levin PA. Fatty Acid Availability Sets Cell Envelope Capacity and Dictates Microbial Cell Size. Curr Biol 2017; 27:1757-1767.e5. [PMID: 28602657 DOI: 10.1016/j.cub.2017.05.076] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 05/20/2017] [Accepted: 05/23/2017] [Indexed: 02/01/2023]
Abstract
Nutrients-and by extension biosynthetic capacity-positively impact cell size in organisms throughout the tree of life. In bacteria, cell size is reduced 3-fold in response to nutrient starvation or accumulation of the alarmone ppGpp, a global inhibitor of biosynthesis. However, whether biosynthetic capacity as a whole determines cell size or whether particular anabolic pathways are more important than others remains an open question. Here we identify fatty acid synthesis as the primary biosynthetic determinant of Escherichia coli size and present evidence supporting a similar role for fatty acids as a positive determinant of size in the Gram-positive bacterium Bacillus subtilis and the single-celled eukaryote Saccharomyces cerevisiae. Altering fatty acid synthesis recapitulated the impact of altering nutrients on cell size and morphology, whereas defects in other biosynthetic pathways had either a negligible or fatty-acid-dependent effect on size. Together, our findings support a novel "outside-in" model in which fatty acid availability sets cell envelope capacity, which in turn dictates cell size. In the absence of ppGpp, limiting fatty acid synthesis leads to cell lysis, supporting a role for ppGpp as a linchpin linking expansion of cytoplasmic volume to the growth of the cell envelope to preserve cellular integrity.
Collapse
Affiliation(s)
- Stephen Vadia
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Jessica L Tse
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Rafael Lucena
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Zhizhou Yang
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Douglas R Kellogg
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
| | - Jue D Wang
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St. Louis, MO 63130, USA.
| |
Collapse
|
43
|
The Fatty Acid Regulator FadR Influences the Expression of the Virulence Cascade in the El Tor Biotype of Vibrio cholerae by Modulating the Levels of ToxT via Two Different Mechanisms. J Bacteriol 2017; 199:JB.00762-16. [PMID: 28115548 DOI: 10.1128/jb.00762-16] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/17/2017] [Indexed: 01/16/2023] Open
Abstract
FadR is a master regulator of fatty acid (FA) metabolism that coordinates the pathways of FA degradation and biosynthesis in enteric bacteria. We show here that a ΔfadR mutation in the El Tor biotype of Vibrio cholerae prevents the expression of the virulence cascade by influencing both the transcription and the posttranslational regulation of the master virulence regulator ToxT. FadR is a transcriptional regulator that represses the expression of genes involved in FA degradation, activates the expression of genes involved in unsaturated FA (UFA) biosynthesis, and also activates the expression of two operons involved in saturated FA (SFA) biosynthesis. Since FadR does not bind directly to the toxT promoter, we determined whether the regulation of any of its target genes indirectly influenced ToxT. This was accomplished by individually inserting a double point mutation into the FadR-binding site in the promoter of each target gene, thereby preventing their activation or repression. Although preventing FadR-mediated activation of fabA, which encodes the enzyme that carries out the first step in UFA biosynthesis, did not significantly influence either the transcription or the translation of ToxT, it reduced its levels and prevented virulence gene expression. In the mutant strain unable to carry out FadR-mediated activation of fabA, expressing fabA ectopically restored the levels of ToxT and virulence gene expression. Taken together, the results presented here indicate that V. cholerae FadR influences the virulence cascade in the El Tor biotype by modulating the levels of ToxT via two different mechanisms.IMPORTANCE Fatty acids (FAs) play important roles in membrane lipid homeostasis and energy metabolism in all organisms. In Vibrio cholerae, the causative agent of the acute intestinal disease cholera, they also influence virulence by binding into an N-terminal pocket of the master virulence regulator, ToxT, and modulating its activity. FadR is a transcription factor that coordinately controls the pathways of FA degradation and biosynthesis in enteric bacteria. This study identifies a new link between FA metabolism and virulence in the El Tor biotype by showing that FadR influences both the transcription and posttranslational regulation of the master virulence regulator ToxT by two distinct mechanisms.
Collapse
|
44
|
Establishment of a multi-species biofilm model and metatranscriptomic analysis of biofilm and planktonic cell communities. Appl Microbiol Biotechnol 2016; 100:7263-79. [PMID: 27102130 DOI: 10.1007/s00253-016-7532-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 03/28/2016] [Accepted: 04/05/2016] [Indexed: 02/06/2023]
Abstract
We collected several biofilm samples from Japanese rivers and established a reproducible multi-species biofilm model that can be analyzed in laboratories. Bacterial abundance at the generic level was highly similar between the planktonic and biofilm communities, whereas comparative metatranscriptomic analysis revealed many upregulated and downregulated genes in the biofilm. Many genes involved in iron-sulfur metabolism, stress response, and cell envelope function were upregulated; biofilm formation is mediated by an iron-dependent signaling mechanism and the signal is relayed to stress-responsive and cell envelope function genes. Flagella-related gene expression was regulated depending upon the growth phase, indicating different roles of flagella during the adherence, maturation, and dispersal steps of biofilm formation. Downregulation of DNA repair genes was observed, indicating that spontaneous mutation frequency would be elevated within the biofilm and that the biofilm is a cradle for generating novel genetic traits. Although the significance remains unclear, genes for rRNA methyltransferase, chromosome partitioning, aminoacyl-tRNA synthase, and cysteine, methionine, leucine, thiamine, nucleotide, and fatty acid metabolism were found to be differentially regulated. These results indicate that planktonic and biofilm communities are in different dynamic states. Studies on biofilm and sessile cells, which have received less attention, are important for understanding microbial ecology and for designing tailor-made anti-biofilm drugs.
Collapse
|
45
|
Sugliani M, Abdelkefi H, Ke H, Bouveret E, Robaglia C, Caffarri S, Field B. An Ancient Bacterial Signaling Pathway Regulates Chloroplast Function to Influence Growth and Development in Arabidopsis. THE PLANT CELL 2016; 28:661-79. [PMID: 26908759 PMCID: PMC4826016 DOI: 10.1105/tpc.16.00045] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 02/19/2016] [Indexed: 05/06/2023]
Abstract
The chloroplast originated from the endosymbiosis of an ancient photosynthetic bacterium by a eukaryotic cell. Remarkably, the chloroplast has retained elements of a bacterial stress response pathway that is mediated by the signaling nucleotides guanosine penta- and tetraphosphate (ppGpp). However, an understanding of the mechanism and outcomes of ppGpp signaling in the photosynthetic eukaryotes has remained elusive. Using the model plant Arabidopsis thaliana, we show that ppGpp is a potent regulator of chloroplast gene expression in vivo that directly reduces the quantity of chloroplast transcripts and chloroplast-encoded proteins. We then go on to demonstrate that the antagonistic functions of different plant RelA SpoT homologs together modulate ppGpp levels to regulate chloroplast function and show that they are required for optimal plant growth, chloroplast volume, and chloroplast breakdown during dark-induced and developmental senescence. Therefore, our results show that ppGpp signaling is not only linked to stress responses in plants but is also an important mediator of cooperation between the chloroplast and the nucleocytoplasmic compartment during plant growth and development.
Collapse
Affiliation(s)
- Matteo Sugliani
- Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France
| | - Hela Abdelkefi
- Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France University of Tunis El Manar, Faculté des Sciences de Tunis, Laboratory of Molecular Genetics, Immunology, and Biotechnology, 2092 El Manar Tunis, Tunisia
| | - Hang Ke
- Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France
| | - Emmanuelle Bouveret
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, CNRS/Aix-Marseille University, Marseille F-13009, France
| | - Christophe Robaglia
- Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France
| | - Stefano Caffarri
- Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France
| | - Ben Field
- Aix Marseille University, Biologie Végétale et Microbiologie Environnementales UMR 7265, Laboratoire de Génétique et Biophysique des Plantes, Marseille F-13009, France CNRS, UMR 7265 Biologie Végétale et Microbiologie Environnementales, Marseille F-13009, France CEA, Bioscience and Biotechnology Institute of Aix-Marseille, Marseille F-13009, France
| |
Collapse
|
46
|
Sivapragasam S, Grove A. Streptomyces coelicolor XdhR is a direct target of (p)ppGpp that controls expression of genes encoding xanthine dehydrogenase to promote purine salvage. Mol Microbiol 2016; 100:701-18. [PMID: 26833627 DOI: 10.1111/mmi.13342] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2016] [Indexed: 12/20/2022]
Abstract
The gene encoding Streptomyces coelicolor xanthine dehydrogenase regulator (XdhR) is divergently oriented from xdhABC, which encodes xanthine dehydrogenase (Xdh). Xdh is required for purine salvage pathways. XdhR was previously shown to repress xdhABC expression. We show that XdhR binds the xdhABC-xdhR intergenic region with high affinity (Kd ∼ 0.5 nM). DNaseI footprinting reveals that this complex formation corresponds to XdhR binding the xdhR gene promoter at two adjacent sites; at higher protein concentrations, protection expands to a region that overlaps the transcriptional and translational start sites of xdhABC. While substrates for Xdh have little effect on DNA binding, GTP and ppGpp dissociate the DNA-XdhR complex. Progression of cells to stationary phase, a condition associated with increased (p)ppGpp production, leads to elevated xdhB expression; in contrast, inhibition of Xdh by allopurinol results in xdhB repression. We propose that XdhR is a direct target of (p)ppGpp, and that expression of xdhABC is upregulated during the stringent response to promote purine salvage pathways, maintain GTP homeostasis and ensure continued (p)ppGpp synthesis. During exponential phase growth, basal levels of xdhABC expression may be achieved by GTP serving as a lower-affinity XdhR ligand.
Collapse
Affiliation(s)
- Smitha Sivapragasam
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Anne Grove
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| |
Collapse
|
47
|
Klochko VV, Zelena LB, Kim JY, Avdeeva LV, Reva ON. Prospects of a new antistaphylococcal drug batumin revealed by molecular docking and analysis of the complete genome sequence of the batumin-producer Pseudomonas batumici UCM B-321. Int J Antimicrob Agents 2016; 47:56-61. [DOI: 10.1016/j.ijantimicag.2015.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/25/2015] [Accepted: 10/02/2015] [Indexed: 11/16/2022]
|
48
|
Röttig A, Zurek PJ, Steinbüchel A. Assessment of bacterial acyltransferases for an efficient lipid production in metabolically engineered strains of E. coli. Metab Eng 2015; 32:195-206. [PMID: 26460058 DOI: 10.1016/j.ymben.2015.09.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 09/21/2015] [Accepted: 09/25/2015] [Indexed: 12/25/2022]
Abstract
Microbially produced lipids like triacylglycerols or fatty acid ethyl esters are currently of great interest as fuel replacements or other industrially relevant compounds. They can even be produced by non-oleaginous microbes, like Escherichia coli, upon metabolic engineering. However, there is still much room for improvement regarding the yield for a competitive microbial production of lipids or biofuels. We genetically engineered E. coli by expressing fadD, fadR, pgpB, plsB and 'tesA in combination with atfA from Acinetobacter baylyi. A total fatty acid contents of up to 16% (w/w) was obtained on complex media, corresponding to approximately 9% (w/w) triacylglycerols and representing the highest titers of fatty acids and triacylglycerols obtained in E. coli under comparable cultivation conditions, so far. To evaluate further possibilities for an optimization of lipid production, ten promising bacterial wax ester synthase/acyl-Coenzyme A:diacylglycerol acyltransferases were tested and compared. While highest triacylglycerol storage was achieved with AtfA, the mutated variant AtfA-G355I turned out to be most suitable for fatty acid ethyl ester biosynthesis and enabled an accumulation of approx. 500 mg/L without external ethanol supplementation.
Collapse
Affiliation(s)
- Annika Röttig
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany
| | - Paul Jannis Zurek
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany
| | - Alexander Steinbüchel
- Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, D-48149 Münster, Germany; Faculty of Environmental Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
| |
Collapse
|
49
|
Zhang H, Zheng B, Gao R, Feng Y. Binding of Shewanella FadR to the fabA fatty acid biosynthetic gene: implications for contraction of the fad regulon. Protein Cell 2015; 6:667-679. [PMID: 26050090 PMCID: PMC4537474 DOI: 10.1007/s13238-015-0172-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 05/06/2015] [Indexed: 11/25/2022] Open
Abstract
The Escherichia coli fadR protein product, a paradigm/prototypical FadR regulator, positively regulates fabA and fabB, the two critical genes for unsaturated fatty acid (UFA) biosynthesis. However the scenario in the other Ɣ-proteobacteria, such as Shewanella with the marine origin, is unusual in that Rodionov and coworkers predicted that only fabA (not fabB) has a binding site for FadR protein. It raised the possibility of fad regulon contraction. Here we report that this is the case. Sequence alignment of the FadR homologs revealed that the N-terminal DNA-binding domain exhibited remarkable similarity, whereas the ligand-accepting motif at C-terminus is relatively-less conserved. The FadR homologue of S. oneidensis (referred to FadR_she) was over-expressed and purified to homogeneity. Integrative evidence obtained by FPLC (fast protein liquid chromatography) and chemical cross-linking analyses elucidated that FadR_she protein can dimerize in solution, whose identity was determined by MALDI-TOF-MS. In vitro data from electrophoretic mobility shift assays suggested that FadR_she is almost functionally-exchangeable/equivalent to E. coli FadR (FadR_ec) in the ability of binding the E. coli fabA (and fabB) promoters. In an agreement with that of E. coli fabA, S. oneidensis fabA promoter bound both FadR_she and FadR_ec, and was disassociated specifically with the FadR regulatory protein upon the addition of long-chain acyl-CoA thioesters. To monitor in vivo effect exerted by FadR on Shewanella fabA expression, the native promoter of S. oneidensis fabA was fused to a LacZ reporter gene to engineer a chromosome fabA-lacZ transcriptional fusion in E. coli. As anticipated, the removal of fadR gene gave about 2-fold decrement of Shewanella fabA expression by β-gal activity, which is almost identical to the inhibitory level by the addition of oleate. Therefore, we concluded that fabA is contracted to be the only one member of fad regulon in the context of fatty acid synthesis in the marine bacteria Shewanella genus.
Collapse
Affiliation(s)
- Huimin Zhang
- Department of Medical Microbiology & Parasitology, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Beiwen Zheng
- Department of Medical Microbiology & Parasitology, Zhejiang University School of Medicine, Hangzhou, 310058 China.,State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Rongsui Gao
- Department of Medical Microbiology & Parasitology, Zhejiang University School of Medicine, Hangzhou, 310058 China
| | - Youjun Feng
- Department of Medical Microbiology & Parasitology, Zhejiang University School of Medicine, Hangzhou, 310058 China.,State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Zhejiang University School of Medicine, Hangzhou, 310058 China
| |
Collapse
|
50
|
Reassessment of the Genetic Regulation of Fatty Acid Synthesis in Escherichia coli: Global Positive Control by the Dual Functional Regulator FadR. J Bacteriol 2015; 197:1862-72. [PMID: 25802297 DOI: 10.1128/jb.00064-15] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 03/11/2015] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED In Escherichia coli, the FadR transcriptional regulator represses the expression of fatty acid degradation (fad) genes. However, FadR is also an activator of the expression of fabA and fabB, two genes involved in unsaturated fatty acid synthesis. Therefore, FadR plays an important role in maintaining the balance between saturated and unsaturated fatty acids in the membrane. We recently showed that FadR also activates the promoter upstream of the fabH gene (L. My, B. Rekoske, J. J. Lemke, J. P. Viala, R. L. Gourse, and E. Bouveret, J Bacteriol 195:3784-3795, 2013, doi:10.1128/JB.00384-13). Furthermore, recent transcriptomic and proteomic data suggested that FadR activates the majority of fatty acid (FA) synthesis genes. In the present study, we tested the role of FadR in the expression of all genes involved in FA synthesis. We found that FadR activates the transcription of all tested FA synthesis genes, and we identified the FadR binding site for each of these genes. This necessitated the reassessment of the transcription start sites for accA and accB genes described previously, and we provide evidence for the presence of multiple promoters driving the expression of these genes. We showed further that regulation by FadR impacts the amount of FA synthesis enzymes in the cell. Our results show that FadR is a global regulator of FA metabolism in E. coli, acting both as a repressor of catabolism and an activator of anabolism, two directly opposing pathways. IMPORTANCE In most bacteria, a transcriptional regulator tunes the level of FA synthesis enzymes. Oddly, such a global regulator still was missing for E. coli, which nonetheless is one of the prominent model bacteria used for engineering biofuel production using the FA synthesis pathway. Our work identifies the FadR functional dual regulator as a global activator of almost all FA synthesis genes in E. coli. Because FadR also is the repressor of FA degradation, FadR acts both as a repressor and an activator of the two opposite pathways of FA degradation and synthesis. Our results show that there are still discoveries waiting to be made in the understanding of the genetic regulation of FA synthesis, even in the very well-known bacterium E. coli.
Collapse
|