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da Cruz Nizer WS, Adams ME, Montgomery MC, Allison KN, Beaulieu C, Overhage J. Genetic determinants of increased sodium hypochlorite and ciprofloxacin susceptibility in Pseudomonas aeruginosa PA14 biofilms. BIOFOULING 2024:1-17. [PMID: 39189148 DOI: 10.1080/08927014.2024.2395378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 06/12/2024] [Accepted: 08/15/2024] [Indexed: 08/28/2024]
Abstract
Reactive chlorine species (RCS) like sodium hypochlorite (NaOCl) are potent oxidizing agents and widely used biocides in surface disinfection, water treatment, and biofilm elimination. Moreover, RCS are also produced by the human immune system to kill invading pathogens. However, bacteria have developed mechanisms to survive the damage caused by RCS. Using the comprehensive Pseudomonas aeruginosa PA14 transposon mutant library in a genetic screen, we identified a total of 28 P. aeruginosa PA14 mutants whose biofilms showed increased susceptibility to NaOCl in comparison to PA14 WT biofilms. Of these, ten PA14 mutants with a disrupted apaH, PA0793, acsA, PA1506, PA1547, PA3728, yajC, queA, PA3869, or PA14_32840 gene presented a 4-fold increase in NaOCl susceptibility compared to wild-type biofilms. While none of these mutants showed a defect in biofilm formation or attenuated susceptibility of biofilms toward the oxidant hydrogen peroxide (H2O2), all but PA14_32840 also exhibited a 2-4-fold increase in susceptibility toward the antibiotic ciprofloxacin. Further analyses revealed attenuated levels of intracellular ROS and catalase activity only for the apaH and PA1547 mutant, providing insights into the oxidative stress response in P. aeruginosa biofilms. The findings of this paper highlight the complexity of biofilm resistance and the intricate interplay between different mechanisms to survive oxidative stress. Understanding resistance strategies adopted by biofilms is crucial for developing more effective ways to fight resistant bacteria, ultimately contributing to better management of bacterial growth and resistance in clinical and environmental settings.
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Affiliation(s)
| | | | | | | | - Carole Beaulieu
- Department of Health Sciences, Carleton University, Ottawa, Canada
| | - Joerg Overhage
- Department of Health Sciences, Carleton University, Ottawa, Canada
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Systems-Wide Dissection of Organic Acid Assimilation in Pseudomonas aeruginosa Reveals a Novel Path To Underground Metabolism. mBio 2022; 13:e0254122. [PMID: 36377867 PMCID: PMC9765439 DOI: 10.1128/mbio.02541-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The human pathogen Pseudomonas aeruginosa (Pa) is one of the most frequent and severe causes of nosocomial infection. This organism is also a major cause of airway infections in people with cystic fibrosis (CF). Pa is known to have a remarkable metabolic plasticity, allowing it to thrive under diverse environmental conditions and ecological niches; yet, little is known about the central metabolic pathways that sustain its growth during infection or precisely how these pathways operate. In this work, we used a combination of 'omics approaches (transcriptomics, proteomics, metabolomics, and 13C-fluxomics) and reverse genetics to provide systems-level insight into how the infection-relevant organic acids succinate and propionate are metabolized by Pa. Moreover, through structural and kinetic analysis of the 2-methylcitrate synthase (2-MCS; PrpC) and its paralogue citrate (CIT) synthase (GltA), we show how these two crucial enzymatic steps are interconnected in Pa organic acid assimilation. We found that Pa can rapidly adapt to the loss of GltA function by acquiring mutations in a transcriptional repressor, which then derepresses prpC expression. Our findings provide a clear example of how "underground metabolism," facilitated by enzyme substrate promiscuity, "rewires" Pa metabolism, allowing it to overcome the loss of a crucial enzyme. This pathogen-specific knowledge is critical for the advancement of a model-driven framework to target bacterial central metabolism. IMPORTANCE Pseudomonas aeruginosa is an opportunistic human pathogen that, due to its unrivalled resistance to antibiotics, ubiquity in the built environment, and aggressiveness in infection scenarios, has acquired the somewhat dubious accolade of being designated a "critical priority pathogen" by the WHO. In this work, we uncover the pathways and mechanisms used by P. aeruginosa to grow on a substrate that is abundant at many infection sites: propionate. We found that if the organism is prevented from metabolizing propionate, the substrate turns from being a convenient nutrient source into a potent poison, preventing bacterial growth. We further show that one of the enzymes involved in these reactions, 2-methylcitrate synthase (PrpC), is promiscuous and can moonlight for another essential enzyme in the cell (citrate synthase). Indeed, mutations that abolish citrate synthase activity (which would normally prevent the cell from growing) can be readily overcome if the cell acquires additional mutations that increase the expression of PrpC. This is a nice example of the evolutionary utility of so-called "underground metabolism."
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Ricci L, Seifert A, Bernacchi S, Fino D, Pirri CF, Re A. Leveraging substrate flexibility and product selectivity of acetogens in two-stage systems for chemical production. Microb Biotechnol 2022; 16:218-237. [PMID: 36464980 PMCID: PMC9871533 DOI: 10.1111/1751-7915.14172] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 10/31/2022] [Accepted: 11/08/2022] [Indexed: 12/09/2022] Open
Abstract
Carbon dioxide (CO2 ) stands out as sustainable feedstock for developing a circular carbon economy whose energy supply could be obtained by boosting the production of clean hydrogen from renewable electricity. H2 -dependent CO2 gas fermentation using acetogenic microorganisms offers a viable solution of increasingly demonstrated value. While gas fermentation advances to achieve commercial process scalability, which is currently limited to a few products such as acetate and ethanol, it is worth taking the best of the current state-of-the-art technology by its integration within innovative bioconversion schemes. This review presents multiple scenarios where gas fermentation by acetogens integrate into double-stage biotechnological production processes that use CO2 as sole carbon feedstock and H2 as energy carrier for products' synthesis. In the integration schemes here reviewed, the first stage can be biotic or abiotic while the second stage is biotic. When the first stage is biotic, acetogens act as a biological platform to generate chemical intermediates such as acetate, formate and ethanol that become substrates for a second fermentation stage. This approach holds the potential to enhance process titre/rate/yield metrics and products' spectrum. Alternatively, when the first stage is abiotic, the integrated two-stage scheme foresees, in the first stage, the catalytic transformation of CO2 into C1 products that, in the second stage, can be metabolized by acetogens. This latter scheme leverages the metabolic flexibility of acetogens in efficient utilization of the products of CO2 abiotic hydrogenation, namely formate and methanol, to synthesize multicarbon compounds but also to act as flexible catalysts for hydrogen storage or production.
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Affiliation(s)
- Luca Ricci
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
| | | | | | - Debora Fino
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
| | - Candido Fabrizio Pirri
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
| | - Angela Re
- Department of Applied Science and TechnologyPolitecnico di TorinoTurinItaly,Centre for Sustainable Future TechnologiesFondazione Istituto Italiano di TecnologiaTurinItaly
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Kutscha R, Pflügl S. Microbial Upgrading of Acetate into Value-Added Products-Examining Microbial Diversity, Bioenergetic Constraints and Metabolic Engineering Approaches. Int J Mol Sci 2020; 21:ijms21228777. [PMID: 33233586 PMCID: PMC7699770 DOI: 10.3390/ijms21228777] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 10/29/2020] [Accepted: 11/18/2020] [Indexed: 01/20/2023] Open
Abstract
Ecological concerns have recently led to the increasing trend to upgrade carbon contained in waste streams into valuable chemicals. One of these components is acetate. Its microbial upgrading is possible in various species, with Escherichia coli being the best-studied. Several chemicals derived from acetate have already been successfully produced in E. coli on a laboratory scale, including acetone, itaconic acid, mevalonate, and tyrosine. As acetate is a carbon source with a low energy content compared to glucose or glycerol, energy- and redox-balancing plays an important role in acetate-based growth and production. In addition to the energetic challenges, acetate has an inhibitory effect on microorganisms, reducing growth rates, and limiting product concentrations. Moreover, extensive metabolic engineering is necessary to obtain a broad range of acetate-based products. In this review, we illustrate some of the necessary energetic considerations to establish robust production processes by presenting calculations of maximum theoretical product and carbon yields. Moreover, different strategies to deal with energetic and metabolic challenges are presented. Finally, we summarize ways to alleviate acetate toxicity and give an overview of process engineering measures that enable sustainable acetate-based production of value-added chemicals.
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Contextual Flexibility in Pseudomonas aeruginosa Central Carbon Metabolism during Growth in Single Carbon Sources. mBio 2020; 11:mBio.02684-19. [PMID: 32184246 PMCID: PMC7078475 DOI: 10.1128/mbio.02684-19] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that is well known for causing infections in the airways of people with cystic fibrosis. Although it is clear that P. aeruginosa is metabolically well adapted to life in the CF lung, little is currently known about how the organism metabolizes the nutrients available in the airways. In this work, we used a combination of gene expression and isotope tracer (“fluxomic”) analyses to find out exactly where the input carbon goes during growth on two CF-relevant carbon sources, acetate and glycerol (derived from the breakdown of lung surfactant). We found that carbon is routed (“fluxed”) through very different pathways during growth on these substrates and that this is accompanied by an unexpected remodeling of the cell’s electron transfer pathways. Having access to this “blueprint” is important because the metabolism of P. aeruginosa is increasingly being recognized as a target for the development of much-needed antimicrobial agents. Pseudomonas aeruginosa is an opportunistic human pathogen, particularly noted for causing infections in the lungs of people with cystic fibrosis (CF). Previous studies have shown that the gene expression profile of P. aeruginosa appears to converge toward a common metabolic program as the organism adapts to the CF airway environment. However, we still have only a limited understanding of how these transcriptional changes impact metabolic flux at the systems level. To address this, we analyzed the transcriptome, proteome, and fluxome of P. aeruginosa grown on glycerol or acetate. These carbon sources were chosen because they are the primary breakdown products of an airway surfactant, phosphatidylcholine, which is known to be a major carbon source for P. aeruginosa in CF airways. We show that the fluxes of carbon throughout central metabolism are radically different among carbon sources. For example, the newly recognized “EDEMP cycle” (which incorporates elements of the Entner-Doudoroff [ED] pathway, the Embden-Meyerhof-Parnas [EMP] pathway, and the pentose phosphate [PP] pathway) plays an important role in supplying NADPH during growth on glycerol. In contrast, the EDEMP cycle is attenuated during growth on acetate, and instead, NADPH is primarily supplied by the reaction catalyzed by isocitrate dehydrogenase(s). Perhaps more importantly, our proteomic and transcriptomic analyses revealed a global remodeling of gene expression during growth on the different carbon sources, with unanticipated impacts on aerobic denitrification, electron transport chain architecture, and the redox economy of the cell. Collectively, these data highlight the remarkable metabolic plasticity of P. aeruginosa; that plasticity allows the organism to seamlessly segue between different carbon sources, maximizing the energetic yield from each.
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Volpicella M, Leoni C, Manzari C, Chiara M, Picardi E, Piancone E, Italiano F, D'Erchia A, Trotta M, Horner DS, Pesole G, Ceci LR. Transcriptomic analysis of nickel exposure in Sphingobium sp. ba1 cells using RNA-seq. Sci Rep 2017; 7:8262. [PMID: 28811613 PMCID: PMC5557971 DOI: 10.1038/s41598-017-08934-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 07/10/2017] [Indexed: 02/06/2023] Open
Abstract
Nickel acts as cofactor for a number of enzymes of many bacteria species. Its homeostasis is ensured by proteins working as ion efflux or accumulation systems. These mechanisms are also generally adopted to counteract life-threatening high extra-cellular Ni2+ concentrations. Little is known regarding nickel tolerance in the genus Sphingobium. We studied the response of the novel Sphingobium sp. ba1 strain, able to adapt to high Ni2+ concentrations. Differential gene expression in cells cultured in 10 mM Ni2+, investigated by RNA-seq analysis, identified 118 differentially expressed genes. Among the 90 up-regulated genes, a cluster including genes coding for nickel and other metal ion efflux systems (similar to either cnrCBA, nccCBA or cznABC) and for a NreB-like permease was found. Comparative analyses among thirty genomes of Sphingobium species show that this cluster is conserved only in two cases, while in the other genomes it is partially present or even absent. The differential expression of genes encoding proteins which could also work as Ni2+-accumulators (HupE/UreJ-like protein, NreA and components of TonB-associated transport and copper-homeostasis systems) was also detected. The identification of Sphingobium sp. ba1 strain adaptive mechanisms to nickel ions, can foster its possible use for biodegradation of poly-aromatic compounds in metal-rich environments.
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Affiliation(s)
- M Volpicella
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - C Leoni
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - C Manzari
- IBIOM-CNR, Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Bari, Italy
| | - M Chiara
- Department of Biosciences, University of Milan, Milan, Italy
| | - E Picardi
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.,IBIOM-CNR, Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Bari, Italy
| | - E Piancone
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - F Italiano
- IPCF-CNR, Institute for Chemical-Physical Processes, Bari, Italy
| | - A D'Erchia
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.,IBIOM-CNR, Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Bari, Italy
| | - M Trotta
- IPCF-CNR, Institute for Chemical-Physical Processes, Bari, Italy
| | - D S Horner
- IBIOM-CNR, Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Bari, Italy.,Department of Biosciences, University of Milan, Milan, Italy
| | - G Pesole
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.,IBIOM-CNR, Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Bari, Italy
| | - L R Ceci
- IBIOM-CNR, Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies, Bari, Italy.
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Kim MJ, Kim J, Lee HY, Noh HJ, Lee KH, Park SJ. Role of AcsR in expression of the acetyl-CoA synthetase gene in Vibrio vulnificus. BMC Microbiol 2015; 15:86. [PMID: 25887971 PMCID: PMC4409781 DOI: 10.1186/s12866-015-0418-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 03/25/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND VarS/VarA is one of the global factors regulating diverse aspects of the metabolism and virulence of bacteria including pathogenic Vibrio spp. An experiment to identify the VarS/VarA-regulon in V. vulnificus revealed that a putative LuxR-type transcriptional regulator was down-regulated in ΔvarA mutant. To investigate the roles of this regulatory cascade, the target gene regulated by a LuxR-regulator was identified and its expression was characterized. RESULTS Transcriptomic analysis of the mutant deficient in this LuxR-type regulator showed that the acsA gene encoding acetyl-CoA synthetase was down-regulated. Thus, this regulator was named AcsR for "regulator of acetyl-CoA synthetase". A putative histidine kinase gene, acsS, was located five ORFs downstream of the acsR gene. Expression of an acsA::luxAB transcriptional fusion was decreased in both ΔacsR and ΔacsS mutants. Similar to a ΔacsA mutant, strains carrying deletions either in acsR or acsS grew slowly than wild type in a minimal medium with acetate as a sole carbon source. Growth defect of the ΔacsR strain in acetate-minimal medium was restored by complementation. To investigate if AcsR directly regulates acsA expression, in vitro-gel shift assays were performed using the recombinant AcsR and the regulatory region of the acsA gene, showing that AcsR specifically bound the upstream region of the acsA ORF. CONCLUSION This study indicates that the VarS/VarA system plays a role in V. vulnificus metabolism via regulating AcsR, which in turn controls acetate metabolism by activating the transcription of the acetyl-CoA synthetase gene.
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Affiliation(s)
- Min Jung Kim
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, 120-752, South Korea.
| | - Juri Kim
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, 120-752, South Korea.
| | - Hye Yeon Lee
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, 120-752, South Korea.
| | - Hyeon Jin Noh
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, 120-752, South Korea.
| | - Kyu-Ho Lee
- Department of Life Science, Sogang University, Seoul, 121-742, South Korea.
| | - Soon-Jung Park
- Department of Environmental Medical Biology and Institute of Tropical Medicine, Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Seoul, 120-752, South Korea.
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Salvador M, Argandoña M, Pastor JM, Bernal V, Cánovas M, Csonka LN, Nieto JJ, Vargas C. Contribution of RpoS to metabolic efficiency and ectoines synthesis during the osmo- and heat-stress response in the halophilic bacterium Chromohalobacter salexigens. ENVIRONMENTAL MICROBIOLOGY REPORTS 2015; 7:301-311. [PMID: 25417903 DOI: 10.1111/1758-2229.12249] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 10/16/2014] [Indexed: 06/04/2023]
Abstract
Chromohalobacter salexigens is a halophilic γ-proteobacterium that responds to osmotic and heat stresses by accumulating ectoine and hydroxyectoine respectively. Evolution has optimized its metabolism to support high production of ectoines. We analysed the effect of an rpoS mutation in C. salexigens metabolism and ectoines synthesis. In long-term adapted cells, the rpoS strain was osmosensitive but not thermosensitive and showed unaltered ectoines content, suggesting that RpoS regulates ectoine(s)-independent osmoadaptive mechanisms. RpoS is involved in the regulation of C. salexigens metabolic adaptation to stress, as early steps of glucose oxidation through the Entner-Doudoroff pathway were deregulated in the rpoS mutant, leading to improved metabolic efficiency at low salinity. Moreover, a reduced pyruvate (but not acetate) overflow was displayed by the rpoS strain at low salt, probably linked to a slowdown in gluconate production and/or subsequent metabolism. Interestingly, RpoS does not seem to be the main regulator triggering the immediate transcriptional response of ectoine synthesis to osmotic or thermal upshifts. However, it contributed to the expression of the ect genes in cells previously adapted to low or high salinity.
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Affiliation(s)
- Manuel Salvador
- Department of Microbiology and Parasitology, Faculty of Pharmacy, University of Seville, Seville, 41012, Spain
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Analysis of the molecular response of Pseudomonas putida KT2440 to the next-generation biofuel n-butanol. J Proteomics 2015; 122:11-25. [PMID: 25829261 DOI: 10.1016/j.jprot.2015.03.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 02/25/2015] [Accepted: 03/10/2015] [Indexed: 11/24/2022]
Abstract
UNLABELLED To increase the efficiency of biocatalysts a thorough understanding of the molecular response of the biocatalyst to precursors, products and environmental conditions applied in bioconversions is essential. Here we performed a comprehensive proteome and phospholipid analysis to characterize the molecular response of the potential biocatalyst Pseudomonas putida KT2440 to the next-generation biofuel n-butanol. Using complementary quantitative proteomics approaches we were able to identify and quantify 1467 proteins, corresponding to 28% of the total KT2440 proteome. 256 proteins were altered in abundance in response to n-butanol. The proteome response entailed an increased abundance of enzymes involved in n-butanol degradation including quinoprotein alcohol dehydrogenases, aldehyde dehydrogenases and enzymes of fatty acid beta oxidation. From these results we were able to construct a pathway for the metabolism of n-butanol in P. putida. The initial oxidation of n-butanol is catalyzed by at least two quinoprotein ethanol dehydrogenases (PedE and PedH). Growth of mutants lacking PedE and PedH on n-butanol was significantly impaired, but not completely inhibited, suggesting that additional alcohol dehydrogenases can at least partially complement their function in KT2440. Furthermore, phospholipid profiling revealed a significantly increased abundance of lyso-phospholipids in response to n-butanol, indicating a rearrangement of the lipid bilayer. BIOLOGICAL SIGNIFICANCE n-butanol is an important bulk chemical and a promising alternative to gasoline as a transportation fuel. Due to environmental concerns as well as increasing energy prices there is a growing interest in sustainable and cost-effective biotechnological production processes for the production of bulk chemicals and transportation fuels from renewable resources. n-butanol fermentation is well established in Clostridiae, but the efficiency of n-butanol production is mainly limited by its toxicity. Therefore bacterial strains with higher intrinsic tolerance to n-butanol have to be selected as hosts for n-butanol production. Pseudomonas bacteria are metabolically very versatile and exhibit a high intrinsic tolerance to organic solvents making them suitable candidates for bioconversion processes. A prerequisite for a potential production of n-butanol in Pseudomonas bacteria is a thorough understanding of the molecular adaption processes caused by n-butanol and the identification of enzymes involved in n-butanol metabolization. This work describes the impact of n-butanol on the proteome and the phospholipid composition of the reference strain P. putida KT2440. The high proteome coverage of our proteomics survey allowed us to reconstruct the degradation pathway of n-butanol and to monitor the changes in the energy metabolism of KT2440 induced by n-butanol. Key enzymes involved in n-butanol degradation identified in study will be interesting targets for optimization of n-butanol production in Pseudomonads. The present work and the identification of key enzymes involved in butanol metabolism may serve as a fundament to develop new or improve existing strategies for the biotechnological production of the next-generation biofuel n-butanol in Pseudomonads.
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Sahonero-Canavesi DX, Sohlenkamp C, Sandoval-Calderón M, Lamsa A, Pogliano K, López-Lara IM, Geiger O. Fatty acid-releasing activities in Sinorhizobium meliloti include unusual diacylglycerol lipase. Environ Microbiol 2015; 17:3391-406. [PMID: 25711932 DOI: 10.1111/1462-2920.12814] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 02/11/2015] [Accepted: 02/11/2015] [Indexed: 11/28/2022]
Abstract
Phospholipids are well known for their membrane-forming properties and thereby delimit any cell from the exterior world. In addition, membrane phospholipids can act as precursors for signals and other biomolecules during their turnover. Little is known about phospholipid signalling, turnover and remodelling in bacteria. Recently, we showed that a FadD-deficient mutant of Sinorhizobium meliloti, unable to convert free fatty acids to their coenzyme A derivatives, accumulates free fatty acids during the stationary phase of growth. Enzymatic activities responsible for the generation of these free fatty acids were unknown in rhizobia. Searching the genome of S. meliloti, we identified a potential lysophospholipase (SMc04041) and two predicted patatin-like phospholipases A (SMc00930, SMc01003). Although SMc00930 as well as SMc01003 contribute to the release of free fatty acids in S. meliloti, neither one can use phospholipids as substrates. Here we show that SMc01003 converts diacylglycerol to monoacylglycerol and a fatty acid, and that monoacylglycerol can be further degraded by SMc01003 to another fatty acid and glycerol. A SMc01003-deficient mutant of S. meliloti transiently accumulates diacylglycerol, suggesting that SMc01003 also acts as diacylglycerol lipase (DglA) in its native background. Expression of the DglA lipase in Escherichia coli causes lysis of cells in stationary phase of growth.
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Affiliation(s)
- Diana X Sahonero-Canavesi
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad s/n, Apdo. Postal 565-A, Cuernavaca, Morelos, CP 62210, Mexico
| | - Christian Sohlenkamp
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad s/n, Apdo. Postal 565-A, Cuernavaca, Morelos, CP 62210, Mexico
| | - Mario Sandoval-Calderón
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad s/n, Apdo. Postal 565-A, Cuernavaca, Morelos, CP 62210, Mexico
| | - Anne Lamsa
- Division of Biological Sciences, University of California, San Diego, CA, 92093, USA
| | - Kit Pogliano
- Division of Biological Sciences, University of California, San Diego, CA, 92093, USA
| | - Isabel M López-Lara
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad s/n, Apdo. Postal 565-A, Cuernavaca, Morelos, CP 62210, Mexico
| | - Otto Geiger
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad s/n, Apdo. Postal 565-A, Cuernavaca, Morelos, CP 62210, Mexico
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Chen AI, Dolben EF, Okegbe C, Harty CE, Golub Y, Thao S, Ha DG, Willger SD, O'Toole GA, Harwood CS, Dietrich LEP, Hogan DA. Candida albicans ethanol stimulates Pseudomonas aeruginosa WspR-controlled biofilm formation as part of a cyclic relationship involving phenazines. PLoS Pathog 2014; 10:e1004480. [PMID: 25340349 PMCID: PMC4207824 DOI: 10.1371/journal.ppat.1004480] [Citation(s) in RCA: 108] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Accepted: 09/18/2014] [Indexed: 11/19/2022] Open
Abstract
In chronic infections, pathogens are often in the presence of other microbial species. For example, Pseudomonas aeruginosa is a common and detrimental lung pathogen in individuals with cystic fibrosis (CF) and co-infections with Candida albicans are common. Here, we show that P. aeruginosa biofilm formation and phenazine production were strongly influenced by ethanol produced by the fungus C. albicans. Ethanol stimulated phenotypes that are indicative of increased levels of cyclic-di-GMP (c-di-GMP), and levels of c-di-GMP were 2-fold higher in the presence of ethanol. Through a genetic screen, we found that the diguanylate cyclase WspR was required for ethanol stimulation of c-di-GMP. Multiple lines of evidence indicate that ethanol stimulates WspR signaling through its cognate sensor WspA, and promotes WspR-dependent activation of Pel exopolysaccharide production, which contributes to biofilm maturation. We also found that ethanol stimulation of WspR promoted P. aeruginosa colonization of CF airway epithelial cells. P. aeruginosa production of phenazines occurs both in the CF lung and in culture, and phenazines enhance ethanol production by C. albicans. Using a C. albicans adh1/adh1 mutant with decreased ethanol production, we found that fungal ethanol strongly altered the spectrum of P. aeruginosa phenazines in favor of those that are most effective against fungi. Thus, a feedback cycle comprised of ethanol and phenazines drives this polymicrobial interaction, and these relationships may provide insight into why co-infection with both P. aeruginosa and C. albicans has been associated with worse outcomes in cystic fibrosis. In many human infections, several species of microbes are often present. This is typically the case with the disease cystic fibrosis, characterized by thick mucus in the lungs that is colonized by bacteria and fungi. Here, we show evidence that interactions between the bacterium Pseudomonas aeruginosa and the fungus Candida albicans result in attributes of infection that are worse for the human host. We found that ethanol, such as that produced by C. albicans, causes increased levels of a signaling molecule in P. aeruginosa that promotes biofilm formation. Biofilm formation by P. aeruginosa is associated with infections that are more difficult to treat. Ethanol stimulated P. aeruginosa colonization of plastic surfaces and airway cells, and we identified components of this mechanism. Fungally-produced ethanol also changes the spectrum of phenazine toxins produced by P. aeruginosa, and phenazines are associated with worse lung function in people with cystic fibrosis. In light of the fact that phenazines interact with C. albicans to promote ethanol production, we propose a positive feedback loop between C. albicans and P. aeruginosa that contributes to worse disease. Our findings could have implications for the study and treatment of multi-species infections.
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Affiliation(s)
- Annie I. Chen
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Emily F. Dolben
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Chinweike Okegbe
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Colleen E. Harty
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Yuriy Golub
- Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Sandy Thao
- Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Dae Gon Ha
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Sven D. Willger
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - George A. O'Toole
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
| | - Caroline S. Harwood
- Department of Microbiology, School of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Lars E. P. Dietrich
- Department of Biological Sciences, Columbia University, New York, New York, United States of America
| | - Deborah A. Hogan
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, United States of America
- * E-mail:
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Gene ercA, encoding a putative iron-containing alcohol dehydrogenase, is involved in regulation of ethanol utilization in Pseudomonas aeruginosa. J Bacteriol 2013; 195:3925-32. [PMID: 23813731 DOI: 10.1128/jb.00531-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several two-component regulatory systems are known to be involved in the signal transduction pathway of the ethanol oxidation system in Pseudomonas aeruginosa ATCC 17933. These sensor kinases and response regulators are organized in a hierarchical manner. In addition, a cytoplasmic putative iron-containing alcohol dehydrogenase (Fe-ADH) encoded by ercA (PA1991) has been identified to play an essential role in this regulatory network. The gene ercA (PA1991) is located next to ercS, which encodes a sensor kinase. Inactivation of ercA (PA1991) by insertion of a kanamycin resistance cassette created mutant NH1. NH1 showed poor growth on various alcohols. On ethanol, NH1 grew only with an extremely extended lag phase. During the induction period on ethanol, transcription of structural genes exa and pqqABCDEH, encoding components of initial ethanol oxidation in P. aeruginosa, was drastically reduced in NH1, which indicates the regulatory function of ercA (PA1991). However, transcription in the extremely delayed logarithmic growth phase was comparable to that in the wild type. To date, the involvement of an Fe-ADH in signal transduction processes has not been reported.
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13
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Kretzschmar U, Khodaverdi V, Adrian L. Transcriptional regulation of the acetyl-CoA synthetase gene acsA in Pseudomonas aeruginosa. Arch Microbiol 2010; 192:685-90. [PMID: 20549193 DOI: 10.1007/s00203-010-0593-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Revised: 05/25/2010] [Accepted: 05/27/2010] [Indexed: 11/25/2022]
Abstract
Pseudomonas aeruginosa ATCC 17933 is able to oxidize ethanol to acetate under aerobic conditions. The P. aeruginosa acetyl-CoA synthetase (ACS) gene acsA was previously identified, and the ACS enzyme described to be required for growth on ethanol as the sole source of carbon and energy. Here, we investigated the transcriptional regulation of the acsA gene using an acsA::lacZ fusion. Transcription of acsA was regulated by the carbon source, and expression was maximal on ethanol, acetate and propionate. In addition, the induction depended on the response regulator ErdR, which also regulates hierarchically arranged genes for ethanol oxidation. Transcription of the acsA gene was repressed by addition of succinate to an ethanol-containing medium. This repression required Crc, the product of the catabolite repression control gene crc.
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Affiliation(s)
- Utta Kretzschmar
- Fachgebiet Angewandte Biochemie, Institut für Biotechnologie, Technische Universität Berlin, Seestrasse 13, 13353 Berlin, Germany
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14
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Mern DS, Ha SW, Khodaverdi V, Gliese N, Görisch H. A complex regulatory network controls aerobic ethanol oxidation in Pseudomonas aeruginosa: indication of four levels of sensor kinases and response regulators. MICROBIOLOGY-SGM 2010; 156:1505-1516. [PMID: 20093290 DOI: 10.1099/mic.0.032847-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In addition to the known response regulator ErbR (former AgmR) and the two-component regulatory system EraSR (former ExaDE), three additional regulatory proteins have been identified as being involved in controlling transcription of the aerobic ethanol oxidation system in Pseudomonas aeruginosa. Two putative sensor kinases, ErcS and ErcS', and a response regulator, ErdR, were found, all of which show significant similarity to the two-component flhSR system that controls methanol and formaldehyde metabolism in Paracoccus denitrificans. All three identified response regulators, EraR (formerly ExaE), ErbR (formerly AgmR) and ErdR, are members of the luxR family. The three sensor kinases EraS (formerly ExaD), ErcS and ErcS' do not contain a membrane domain. Apparently, they are localized in the cytoplasm and recognize cytoplasmic signals. Inactivation of gene ercS caused an extended lag phase on ethanol. Inactivation of both genes, ercS and ercS', resulted in no growth at all on ethanol, as did inactivation of erdR. Of the three sensor kinases and three response regulators identified thus far, only the EraSR (formerly ExaDE) system forms a corresponding kinase/regulator pair. Using reporter gene constructs of all identified regulatory genes in different mutants allowed the hierarchy of a hypothetical complex regulatory network to be established. Probably, two additional sensor kinases and two additional response regulators, which are hidden among the numerous regulatory genes annotated in the genome of P. aeruginosa, remain to be identified.
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Affiliation(s)
- Demissew S Mern
- Helmholtz-University Group Molecular Epidemiology, German Cancer Research Center, Im Neuenheimer Feld 581, D-69120 Heidelberg, Germany
| | - Seung-Wook Ha
- The Barbara Ann Karmanos Cancer Institute, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Viola Khodaverdi
- Fachgebiet Angewandte Biochemie, Institut für Biotechnologie, Technische Universität Berlin, Seestrasse 13, D-13353 Berlin, Germany
| | - Nicole Gliese
- BioGenes GmbH, Koepenicker Strasse 325, D-12555 Berlin, Germany
| | - Helmut Görisch
- Fachgebiet Angewandte Biochemie, Institut für Biotechnologie, Technische Universität Berlin, Seestrasse 13, D-13353 Berlin, Germany
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15
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Gliese N, Khodaverdi V, Görisch H. The PQQ biosynthetic operons and their transcriptional regulation in Pseudomonas aeruginosa. Arch Microbiol 2009; 192:1-14. [PMID: 19902179 DOI: 10.1007/s00203-009-0523-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 10/14/2009] [Accepted: 10/21/2009] [Indexed: 10/20/2022]
Abstract
Gene PA1990 of Pseudomonas aeruginosa, located downstream of pqqE and encoding a putative peptidase, was shown to be involved in excretion of PQQ into the culture supernatant. This gene is cotranscribed with the pqqABCDE cluster and was named pqqH. A PA1990::Km(r) mutant (VK3) did not show any effect in growth behaviour; however, in contrast to the wild-type, no excretion of PQQ into the culture supernatant was observed. The putative pqqF gene of P. aeruginosa was shown to be essential for PQQ biosynthesis. A pqqF::Km(r) mutant did not grow aerobically on ethanol, because of its inability to produce PQQ. Transcription of the pqqABCDEH operon was induced upon aerobic growth on ethanol, 1-propanol, 1,2-propanediol and 1-butanol, while on glycerol, succinate and acetate, transcription was low. Transcription of the pqqABCDEH operon was also found upon anoxic growth on ethanol with nitrate as electron acceptor, but no PQQ was produced. Expression of the pqqABCDEH operon is regulated at the transcriptional level. In contrast, the pqqF operon appeared to be transcribed constitutively at a very low level under all growth conditions studied.
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Affiliation(s)
- Nicole Gliese
- BioGenes GmbH, Koepenicker Strasse 325, Berlin, Germany
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16
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Kretzschmar U, Khodaverdi V, Jeoung JH, Görisch H. Function and transcriptional regulation of the isocitrate lyase in Pseudomonas aeruginosa. Arch Microbiol 2008; 190:151-8. [PMID: 18574579 DOI: 10.1007/s00203-008-0381-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 04/10/2008] [Accepted: 04/29/2008] [Indexed: 11/30/2022]
Abstract
Pseudomonas aeruginosa ATCC 17933 is capable of growing aerobically on ethanol as sole source of carbon and energy. This requires the glyoxylate cycle for replenishing C4-compounds to the TCA cycle. The enzyme isocitrate lyase (ICL) catalyzes the first step of this glyoxylate shunt. Its activity was induced more than 10-fold in response to the carbon sources ethanol or acetate instead of glucose or succinate. We could prove that in P. aeruginosa ICL is essential for aerobic as well as anaerobic utilization of C2-sources. Transcriptional regulation of icl gene (aceA) expression was monitored on different carbon sources by using an aceA-lacZ gene fusion. A strong correlation between promoter and ICL activity indicated regulation at the transcriptional level. But ICL was not simply induced by the mere presence of ethanol in the growth medium as was demonstrated by cultivation on mixed substrates. P. aeruginosa showed diauxic growth on media containing ethanol-succinate or ethanol-glucose mixtures and did not transcribe the aceA gene to metabolize ethanol until succinate or glucose, respectively, were exhausted. Inactivation of the chromosomal aceA gene in P. aeruginosa led to an inability to grow on ethanol and acetate. Promoter activity studies showed that all genes necessary to oxidize ethanol were downregulated in the ICL-negative mutant. But on mixed substrates like ethanol-succinate or ethanol-glucose the mutant exhibited growth and utilized ethanol as well, probably as energy source only.
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Affiliation(s)
- Utta Kretzschmar
- Fachgebiet Technische Biochemie, Institut für Biotechnologie, Technische Universität Berlin, Seestr. 13, 13353 Berlin, Germany
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17
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Palmer KL, Aye LM, Whiteley M. Nutritional cues control Pseudomonas aeruginosa multicellular behavior in cystic fibrosis sputum. J Bacteriol 2007; 189:8079-87. [PMID: 17873029 PMCID: PMC2168676 DOI: 10.1128/jb.01138-07] [Citation(s) in RCA: 445] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The sputum (mucus) layer of the cystic fibrosis (CF) lung is a complex substrate that provides Pseudomonas aeruginosa with carbon and energy to support high-density growth during chronic colonization. Unfortunately, the CF lung sputum layer has been difficult to mimic in animal models of CF disease, and mechanistic studies of P. aeruginosa physiology during growth in CF sputum are hampered by its complexity. In this study, we performed chromatographic and enzymatic analyses of CF sputum to develop a defined, synthetic CF sputum medium (SCFM) that mimics the nutritional composition of CF sputum. Importantly, P. aeruginosa displays similar phenotypes during growth in CF sputum and in SCFM, including similar growth rates, gene expression profiles, carbon substrate preferences, and cell-cell signaling profiles. Using SCFM, we provide evidence that aromatic amino acids serve as nutritional cues that influence cell-cell signaling and antimicrobial activity of P. aeruginosa during growth in CF sputum.
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Affiliation(s)
- Kelli L Palmer
- Section of Molecular Genetics and Microbiology, University of Texas at Austin, 1 University Station, A5000, Austin, TX 78712, USA
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18
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Gao JL, Weissenmayer B, Taylor AM, Thomas-Oates J, López-Lara IM, Geiger O. Identification of a gene required for the formation of lyso-ornithine lipid, an intermediate in the biosynthesis of ornithine-containing lipids. Mol Microbiol 2004; 53:1757-70. [PMID: 15341653 DOI: 10.1111/j.1365-2958.2004.04240.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Under phosphate-limiting conditions, some bacteria replace their membrane phospholipids by lipids not containing any phosphorus. One of these phosphorus-free lipids is an ornithine-containing lipid (OL) that is widespread among eubacteria. In earlier work, we had identified a gene (olsA) required for OL biosynthesis that probably encodes an O-acyltransferase using acyl-acyl carrier protein (acyl-AcpP) as an acyl donor and that converts lyso-ornithine lipid into OL. We now report on a second gene (olsB) required for OL biosynthesis that is needed for the incorporation of radiolabelled ornithine into OL. Overexpression of OlsB in an olsA-deficient mutant of Sinorhizobium (Rhizobium) meliloti leads to the transient accumulation of lyso-ornithine lipid, the biosynthetic intermediate of OL biosynthesis. Overexpression of OlsB in Escherichia coli is sufficient to cause the in vivo formation of lyso-ornithine lipid in this organism and is the cause for a 3-hydroxyacyl-AcpP-dependent acyltransferase activity forming lyso-ornithine lipid from ornithine. These results demonstrate that OlsB is required for the first step of OL biosynthesis, in which ornithine is N-acylated with a 3-hydroxy-fatty acyl residue in order to obtain lyso-ornithine lipid. OL formation in a wild-type S. meliloti is increased upon growth under phosphate-limiting conditions. Expression of OlsB from a broad host range vector leads to the constitutive formation of relatively high amounts of OL (12-14% of total membrane lipids) independently of whether strains are grown in the presence of low or high concentrations of phosphate, suggesting that in S. meliloti the formation of OlsB is usually limiting for the amount of OL formed in this organism. Open reading frames homologous to OlsA and OlsB were identified in many eubacteria and although in S. meliloti the olsB and olsA gene are 14 kb apart, in numerous other bacteria they form an operon.
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Affiliation(s)
- Jun-Lian Gao
- Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, CP62210, Mexico
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19
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Elfari M, Ha SW, Bremus C, Merfort M, Khodaverdi V, Herrmann U, Sahm H, Görisch H. A Gluconobacter oxydans mutant converting glucose almost quantitatively to 5-keto-D-gluconic acid. Appl Microbiol Biotechnol 2004; 66:668-74. [PMID: 15735967 DOI: 10.1007/s00253-004-1721-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Accepted: 07/16/2004] [Indexed: 10/26/2022]
Abstract
Gluconobacter oxydans converts glucose to gluconic acid and subsequently to 2-keto-D-gluconic acid (2-KGA) and 5-keto-D-gluconic acid (5-KGA) by membrane-bound periplasmic pyrroloquinoline quinone-dependent and flavin-dependent dehydrogenases. The product pattern obtained with several strains differed significantly. To increase the production of 5-KGA, which can be converted to industrially important L-(+)-tartaric acid, growth parameters were optimized. Whereas resting cells of G. oxydans ATCC 621H converted about 11% of the available glucose to 2-KGA and 6% to 5-KGA, with growing cells and improved growth under defined conditions (pH 5, 10% pO2, 0.05% pCO2) a conversion yield of about 45% 5-KGA from the available glucose was achieved. As the accumulation of the by-product 2-KGA is highly disadvantageous for an industrial application of G. oxydans, a mutant was generated in which the membrane-bound gluconate-2-dehydrogenase complex was inactivated. This mutant, MF1, grew in a similar way to the wild type, but formation of the undesired 2-KGA was not observed. Under improved growth conditions, mutant MF1 converted the available glucose almost completely (84%) into 5-KGA. Therefore, this newly developed recombinant strain is suitable for the industrial production of 5-KGA.
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Affiliation(s)
- Mustafa Elfari
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestr. 13, 13353, Berlin, Germany
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20
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Gliese N, Khodaverdi V, Schobert M, Görisch H. AgmR controls transcription of a regulon with several operons essential for ethanol oxidation in Pseudomonas aeruginosa ATCC 17933. MICROBIOLOGY-SGM 2004; 150:1851-1857. [PMID: 15184571 DOI: 10.1099/mic.0.26882-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The response regulator AgmR was identified to be involved in the regulation of the quinoprotein ethanol oxidation system of Pseudomonas aeruginosa ATCC 17933. Interruption of the agmR gene by insertion of a kanamycin-resistance cassette resulted in mutant NG3, unable to grow on ethanol. After complementation with the intact agmR gene, growth on ethanol was restored. Transcriptional lacZ fusions were used to identify four operons which are regulated by the AgmR protein: the exaA operon encodes the pyrroloquinoline quinone (PQQ)-dependent ethanol dehydrogenase, the exaBC operon encodes a soluble cytochrome c(550) and an aldehyde dehydrogenase, the pqqABCDE operon carries the PQQ biosynthetic genes, and operon exaDE encodes a two-component regulatory system which controls transcription of the exaA operon. Transcription of exaA was restored by transformation of NG3 with a pUCP20T derivative carrying the exaDE genes under lac-promoter control. These data indicate that the AgmR response regulator and the exaDE two-component regulatory system are organized in a hierarchical manner. Gene PA1977, which appears to form an operon with the agmR gene, was found to be non-essential for growth on ethanol.
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Affiliation(s)
- Nicole Gliese
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany
| | - Viola Khodaverdi
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany
| | - Max Schobert
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany
| | - Helmut Görisch
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany
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21
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Görisch H. The ethanol oxidation system and its regulation in Pseudomonas aeruginosa. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1647:98-102. [PMID: 12686116 DOI: 10.1016/s1570-9639(03)00066-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pseudomonas aeruginosa ATCC 17933, when growing on ethanol, uses a pyrroloquinoline quinone (PQQ)-dependent ethanol oxidation system. The genes coding for the ethanol oxidizing enzyme, a quinoprotein ethanol dehydrogenase (QEDH), cytochrome c(550), which is an essential component of the electron transport chain and accepts the electrons from QEDH, and an NAD-dependent acetaldehyde dehydrogenase form the exaABC gene cluster. Downstream of the exaBC genes the pqqABCDE gene cluster is found, which codes for proteins essential for biosynthesis of the cofactor PQQ. Also essential for growth on ethanol are an acetyl-CoA synthetase encoded by the acsA gene and a malate:quinone oxidoreductase encoded by the mqo gene. The X-ray structure of the soluble QEDH from P. aeruginosa was solved. It is a homodimeric enzyme and, aside from differences in some loops, the folding of QEDH is very similar to the large subunit of the soluble methanol dehydrogenase of methylotrophs, and the PQQ domain of the quinohemoprotein alcohol dehydrogenase from Comamonas testosteroni and P. fluorescens. Transcription from the QEDH (exaA) promoter is regulated by a two component system: a histidine sensor kinase (ExaD), which is presumably located in the cytoplasm, and a response regulator (ExaE). The phenotypic characterization and transcription studies with six regulatory mutants indicate that seven different genes in an hierarchical organization may be involved in regulating the transcription of the ethanol oxidation system and components of acetate metabolism in P. aeruginosa.
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Affiliation(s)
- Helmut Görisch
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestrasse 13, D-13353 Berlin, Germany.
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22
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Kretzschmar U, Rückert A, Jeoung JH, Görisch H. Malate:quinone oxidoreductase is essential for growth on ethanol or acetate in Pseudomonas aeruginosa. MICROBIOLOGY (READING, ENGLAND) 2002; 148:3839-3847. [PMID: 12480887 DOI: 10.1099/00221287-148-12-3839] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Pseudomonas aeruginosa ATCC 17933 growing aerobically on ethanol uses a pyrroloquinoline quinone-dependent ethanol oxidation system. A mutant with an interrupted putative mqo gene, in which malate:quinone oxidoreductase (MQO), an enzyme involved in the citric acid cycle/glyoxylate cycle, was defective, showed a severe growth defect on ethanol and was unable to grow on acetate. Glucose, lactate, succinate or malate supported growth of the mutant. However, an NAD-dependent malate dehydrogenase activity could not be detected. Complementation of the mutant by the wild-type allele of the mqo gene restored wild-type behaviour. The wild-type expressed the dye-dependent MQO and NAD(P)-dependent malic enzymes (MEs). Pyruvate carboxylase (PC) was found upon growth of the wild-type and the mutant on all substrates studied. PC activity in the wild-type was induced on glucose and lactate and was always higher on all substrates in the mqo mutant. In P. aeruginosa ATCC 17933, an active MQO is required for growth on ethanol or acetate, while with glucose, lactate, succinate or malate an apparent bypass route operates, with MEs using malate for generating pyruvate, which is carboxylated to oxaloacetate by PC. To the authors' knowledge, this is the first time that a specific mutant MQO phenotype has been observed, caused by the inactivation of a gene encoding MQO activity. mqo of P. aeruginosa ATCC 17933 corresponds to mqoB (PA4640) of the P. aeruginosa PAO1 genome project.
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Affiliation(s)
- Utta Kretzschmar
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany1
| | - Andreas Rückert
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany1
| | - Jae-Hun Jeoung
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany1
| | - Helmut Görisch
- Fachgebiet Technische Biochemie, Institut für Biotechnologie der Technischen Universität Berlin, Seestraße 13, D-13353 Berlin, Germany1
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