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Control of biofilm-producing Pseudomonas aeruginosa isolated from dairy farm using Virokill silver nano-based disinfectant as an alternative approach. Sci Rep 2022; 12:9452. [PMID: 35676412 PMCID: PMC9177611 DOI: 10.1038/s41598-022-13619-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Accepted: 05/09/2022] [Indexed: 11/08/2022] Open
Abstract
Pseudomonas aeruginosa (P. aeruginosa) is an important opportunistic pathogen that is responsible for many clinical infections in both animals and humans. This study aimed to detect the prevalence of P. aeruginosa in dairy farm's that possess a great importance to dairy industry where it shares in milk spoilage. Evaluation of the efficacy of commonly used disinfectants to control the pathogen in dairy environment and finding a way to overcome high resistance to the used agents. Samples (n = 250) were collected from different environmental components, milk, and milkers' hands. Pathogens were isolated, biofilm was detected and their sensitivity against two commonly used disinfectants and against silver nanoparticles and Virokill AgNPs at different concentrations and contact times were tested. The pathogen significantly prevailed in milk samples (70.0%, P < 0.001). 50 out 74 isolates were biofilm-forming that was significantly obtained from environment (71.8%, P < 0.001). P. aeruginosa showed variable degree of resistance to tested disinfectants but it was significantly sensitive to Virokill AgNPs (200/1000) mg/l at exposure time 24 h (P < 0.001). It was concluded that using Virokill AgNPs in regular sanitation and disinfection of dairy farms, this helps the control of P. aeruginosa subsequently increasing milk quality and improving dairy industry and protecting human health.
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Geiger O, Sohlenkamp C, Vera-Cruz D, Medeot DB, Martínez-Aguilar L, Sahonero-Canavesi DX, Weidner S, Pühler A, López-Lara IM. ExoS/ChvI Two-Component Signal-Transduction System Activated in the Absence of Bacterial Phosphatidylcholine. FRONTIERS IN PLANT SCIENCE 2021; 12:678976. [PMID: 34367203 PMCID: PMC8343143 DOI: 10.3389/fpls.2021.678976] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
Sinorhizobium meliloti contains the negatively charged phosphatidylglycerol and cardiolipin as well as the zwitterionic phosphatidylethanolamine (PE) and phosphatidylcholine (PC) as major membrane phospholipids. In previous studies we had isolated S. meliloti mutants that lack PE or PC. Although mutants deficient in PE are able to form nitrogen-fixing nodules on alfalfa host plants, mutants lacking PC cannot sustain development of any nodules on host roots. Transcript profiles of mutants unable to form PE or PC are distinct; they differ from each other and they are different from the wild type profile. For example, a PC-deficient mutant of S. meliloti shows an increase of transcripts that encode enzymes required for succinoglycan biosynthesis and a decrease of transcripts required for flagellum formation. Indeed, a PC-deficient mutant is unable to swim and overproduces succinoglycan. Some suppressor mutants, that regain swimming and form normal levels of succinoglycan, are altered in the ExoS sensor. Our findings suggest that the lack of PC in the sinorhizobial membrane activates the ExoS/ChvI two-component regulatory system. ExoS/ChvI constitute a molecular switch in S. meliloti for changing from a free-living to a symbiotic life style. The periplasmic repressor protein ExoR controls ExoS/ChvI function and it is thought that proteolytic ExoR degradation would relieve repression of ExoS/ChvI thereby switching on this system. However, as ExoR levels are similar in wild type, PC-deficient mutant and suppressor mutants, we propose that lack of PC in the bacterial membrane provokes directly a conformational change of the ExoS sensor and thereby activation of the ExoS/ChvI two-component system.
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Affiliation(s)
- Otto Geiger
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Christian Sohlenkamp
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Diana Vera-Cruz
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Daniela B. Medeot
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | | | | | - Stefan Weidner
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Alfred Pühler
- Institut für Genomforschung und Systembiologie, Centrum für Biotechnologie (CeBiTec), Universität Bielefeld, Bielefeld, Germany
| | - Isabel M. López-Lara
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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Let-7b-5p in vesicles secreted by human airway cells reduces biofilm formation and increases antibiotic sensitivity of P. aeruginosa. Proc Natl Acad Sci U S A 2021; 118:2105370118. [PMID: 34260396 DOI: 10.1073/pnas.2105370118] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that forms antibiotic-resistant biofilms, which facilitate chronic infections in immunocompromised hosts. We have previously shown that P. aeruginosa secretes outer-membrane vesicles that deliver a small RNA to human airway epithelial cells (AECs), in which it suppresses the innate immune response. Here, we demonstrate that interdomain communication through small RNA-containing membrane vesicles is bidirectional and that microRNAs (miRNAs) in extracellular vesicles (EVs) secreted by human AECs regulate protein expression, antibiotic sensitivity, and biofilm formation by P. aeruginosa Specifically, human EVs deliver miRNA let-7b-5p to P. aeruginosa, which systematically decreases the abundance of proteins essential for biofilm formation, including PpkA and ClpV1-3, and increases the ability of beta-lactam antibiotics to reduce biofilm formation by targeting the beta-lactamase AmpC. Let-7b-5p is bioinformatically predicted to target not only PpkA, ClpV1, and AmpC in P. aeruginosa but also the corresponding orthologs in Burkholderia cenocepacia, another notorious opportunistic lung pathogen, suggesting that the ability of let-7b-5p to reduce biofilm formation and increase beta-lactam sensitivity is not limited to P. aeruginosa Here, we provide direct evidence for transfer of miRNAs in EVs secreted by eukaryotic cells to a prokaryote, resulting in subsequent phenotypic alterations in the prokaryote as a result of this interdomain communication. Since let-7-family miRNAs are in clinical trials to reduce inflammation and because chronic P. aeruginosa lung infections are associated with a hyperinflammatory state, treatment with let-7b-5p and a beta-lactam antibiotic in nanoparticles or EVs may benefit patients with antibiotic-resistant P. aeruginosa infections.
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Khalifa M, Few LL, See Too WC. ChoK-ing the Pathogenic Bacteria: Potential of Human Choline Kinase Inhibitors as Antimicrobial Agents. BIOMED RESEARCH INTERNATIONAL 2020; 2020:1823485. [PMID: 32695809 PMCID: PMC7368946 DOI: 10.1155/2020/1823485] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/25/2020] [Accepted: 06/29/2020] [Indexed: 01/12/2023]
Abstract
Novel antimicrobial agents are crucial to combat antibiotic resistance in pathogenic bacteria. Choline kinase (ChoK) in bacteria catalyzes the synthesis of phosphorylcholine, which is subsequently incorporated into the cell wall or outer membrane. In certain species of bacteria, phosphorylcholine is also used to synthesize membrane phosphatidylcholine. Numerous human ChoK inhibitors (ChoKIs) have been synthesized and tested for anticancer properties. Inhibition of S. pneumoniae ChoK by human ChoKIs showed a promising effect by distorting the cell wall and retarded the growth of this pathogen. Comparison of amino acid sequences at the catalytic sites of putative choline kinases from pathogenic bacteria and human enzymes revealed striking sequence conservation that supports the potential application of currently available ChoKIs for inhibiting bacterial enzymes. We also propose the combined use of ChoKIs and nanoparticles for targeted delivery to the pathogen while shielding the human host from any possible side effects of the inhibitors. More research should focus on the verification of putative bacterial ChoK activities and the characterization of ChoKIs with active enzymes. In conclusion, the presence of ChoK in a wide range of pathogenic bacteria and the distinct function of this enzyme has made it an attractive drug target. This review highlighted the possibility of "choking" bacterial ChoKs by using human ChoKIs.
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Affiliation(s)
- Moad Khalifa
- School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
| | - Ling Ling Few
- School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
| | - Wei Cun See Too
- School of Health Sciences, Health Campus, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan, Malaysia
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5
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Phosphatidylcholine Biosynthesis in Mitis Group Streptococci via Host Metabolite Scavenging. J Bacteriol 2019; 201:JB.00495-19. [PMID: 31501281 PMCID: PMC6805115 DOI: 10.1128/jb.00495-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 08/29/2019] [Indexed: 01/21/2023] Open
Abstract
We lack fundamental information about the composition of the cellular membrane even for the best-studied pathogens of critical significance for human health. The mitis group streptococci are closely linked to humans in health and disease, but their membrane biology is poorly understood. Here, we demonstrate that these streptococci scavenge major human metabolites and use them to synthesize the membrane phospholipid PC. Our work is significant because it identifies a mechanism by which the major human pathogen S. pneumoniae and the primary human oral colonizers S. mitis and S. oralis remodel their membranes in response to host metabolites. The mitis group streptococci include the major human pathogen Streptococcus pneumoniae and the opportunistic pathogens Streptococcus mitis and Streptococcus oralis, which are human oral cavity colonizers and agents of bacteremia and infective endocarditis in immunocompromised patients. Bacterial membrane lipids play crucial roles in microbe-host interactions; for many pathogens, however, the composition of the membrane is poorly understood. In this study, we characterized the lipidomes of selected species of mitis group streptococci and investigated the mechanistic basis for biosynthesis of the phospholipid phosphatidylcholine (PC). PC is a major lipid in eukaryotic cellular membranes, but it is considered to be comparatively rare in bacterial taxa. Using liquid chromatography-mass spectrometry in conjunction with stable isotope tracing, we determined that mitis group streptococci synthesize PC via a rare host-metabolite-scavenging pathway, the glycerophosphocholine (GPC) pathway, which is largely uncharacterized in bacteria. Our work demonstrates that mitis group streptococci, including S. pneumoniae, remodel their membranes in response to the major human metabolites GPC and lysophosphatidylcholine. IMPORTANCE We lack fundamental information about the composition of the cellular membrane even for the best-studied pathogens of critical significance for human health. The mitis group streptococci are closely linked to humans in health and disease, but their membrane biology is poorly understood. Here, we demonstrate that these streptococci scavenge major human metabolites and use them to synthesize the membrane phospholipid PC. Our work is significant because it identifies a mechanism by which the major human pathogen S. pneumoniae and the primary human oral colonizers S. mitis and S. oralis remodel their membranes in response to host metabolites.
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Liu X, Long D, You H, Yang D, Zhou S, Zhang S, Li M, He M, Xiong M, Wang X. Phosphatidylcholine affects the secretion of the alkaline phosphatase PhoA in Pseudomonas strains. Microbiol Res 2016; 192:21-29. [DOI: 10.1016/j.micres.2016.02.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 01/05/2016] [Accepted: 02/01/2016] [Indexed: 01/13/2023]
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Ding W, Smulan LJ, Hou NS, Taubert S, Watts JL, Walker AK. s-Adenosylmethionine Levels Govern Innate Immunity through Distinct Methylation-Dependent Pathways. Cell Metab 2015; 22:633-45. [PMID: 26321661 PMCID: PMC4598287 DOI: 10.1016/j.cmet.2015.07.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 05/29/2015] [Accepted: 07/17/2015] [Indexed: 12/13/2022]
Abstract
s-adenosylmethionine (SAM) is the sole methyl donor modifying histones, nucleic acids, and phospholipids. Its fluctuation affects hepatic phosphatidylcholine (PC) synthesis or may be linked to variations in DNA or histone methylation. Physiologically, low SAM is associated with lipid accumulation, tissue injury, and immune responses in fatty liver disease. However, molecular connections among SAM limitation, methyltransferases, and disease-associated phenotypes are unclear. We find that low SAM can activate or attenuate Caenorhabditis elegans immune responses. Immune pathways are stimulated downstream of PC production on a non-pathogenic diet. In contrast, distinct SAM-dependent mechanisms limit survival on pathogenic Pseudomonas aeruginosa. C. elegans undertakes a broad transcriptional response to pathogens and we find that low SAM restricts H3K4me3 at Pseudomonas-responsive promoters, limiting their expression. Furthermore, this response depends on the H3K4 methyltransferase set-16/MLL. Thus, our studies provide molecular links between SAM and innate immune functions and suggest that SAM depletion may limit stress-induced gene expression.
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Affiliation(s)
- Wei Ding
- Program in Molecular Medicine, UMass Worcester, 373 Plantation Street, Worcester, MA 01605, USA
| | - Lorissa J Smulan
- Program in Molecular Medicine, UMass Worcester, 373 Plantation Street, Worcester, MA 01605, USA
| | - Nicole S Hou
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics (CMMT) and Child & Family Research Institute (CFRI), University of British Columbia (UBC), Vancouver, BC V5Z 4H4, Canada
| | - Stefan Taubert
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics (CMMT) and Child & Family Research Institute (CFRI), University of British Columbia (UBC), Vancouver, BC V5Z 4H4, Canada
| | - Jennifer L Watts
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-6340, USA
| | - Amy K Walker
- Program in Molecular Medicine, UMass Worcester, 373 Plantation Street, Worcester, MA 01605, USA.
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Wang Y, Wang J, Li Y, Wang B, Tao G, Wang X. Structure characterization of phospholipids and lipid A of Pseudomonas putida KT2442. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2015; 21:739-746. [PMID: 26579930 DOI: 10.1255/ejms.1390] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Pseudomonas putida KT2442 is an important bacterium for producing various types of polyhydroxyalkanoate polymers. Phospholipids and lipid A in membranes of P. putida play important roles in stress responses, but detailed structural information of these lipids is not known. In this study, phospholipids and lipid A were isolated from P. putida KT2442, and their structures were analyzed using thin layer chromatography, high performance liquid chromatography, and electrospray ionization/mass spectrometry. Major phospholipids in P. putida KT2442 were phosphatidylethanolamine (79.9%), phosphatidylglycero1 (12.7%), and cardiolipin (7.4%), with C16:1 and/or C18:1 acyl chains. Four lipid A species were found in P. putida KT2442: two are hexa-acylated, and the other two are penta-acylated. Compared with lipid A of P. aeruginosa, P. putida lipid A has less hydroxylation on the secondary acyl chains and less modification. Therefore, P. putida lipid A could be used as a base structure to investigate lipid A modification of P. aeruginosa for understanding its pathogenesis.
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Affiliation(s)
- Yuqian Wang
- State Key Laboratory of Food Science and Technology, and School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, China.
| | - Jianli Wang
- State Key Laboratory of Food Science and Technology, and School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, Chinaof Biotechnology, State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, China.
| | - Ye Li
- State Key Laboratory of Food Science and Technology, and School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, Chinaotechnology, State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, China.
| | - Biwen Wang
- State Key Laboratory of Food Science and Technology, and School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, Chinaotechnology, State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, China.
| | - Guanjun Tao
- State Key Laboratory of Food Science and Technology, and School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, Chinaotechnology, State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, China.
| | - Xiaoyuan Wang
- State Key Laboratory of Food Science and Technology, and School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, Chinaechnology, State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 21422, China.
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9
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Legionella dumoffii utilizes exogenous choline for phosphatidylcholine synthesis. Int J Mol Sci 2014; 15:8256-79. [PMID: 24821544 PMCID: PMC4057730 DOI: 10.3390/ijms15058256] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 04/20/2014] [Accepted: 04/23/2014] [Indexed: 12/05/2022] Open
Abstract
Phosphatidycholine (PC) is the major membrane-forming phospholipid in eukaryotes but it has been found in only a limited number of prokaryotes. Bacteria synthesize PC via the phospholipid N-methylation pathway (Pmt) or via the phosphatidylcholine synthase pathway (Pcs) or both. Here, we demonstrated that Legionella dumoffii has the ability to utilize exogenous choline for phosphatidylcholine (PC) synthesis when bacteria grow in the presence of choline. The Pcs seems to be a primary pathway for synthesis of this phospholipid in L. dumoffii. Structurally different PC species were distributed in the outer and inner membranes. As shown by the LC/ESI-MS analyses, PC15:0/15:0, PC16:0/15:0, and PC17:0/17:1 were identified in the outer membrane and PC14:0/16:0, PC16:0/17:1, and PC20:0/15:0 in the inner membrane. L. dumoffii pcsA gene encoding phosphatidylcholine synthase revealed the highest sequence identity to pcsA of L. bozemanae (82%) and L. longbeachae (81%) and lower identity to pcsA of L. drancourtii (78%) and L. pneumophila (71%). The level of TNF-α in THP1-differentiated cells induced by live and temperature-killed L. dumoffii cultured on a medium supplemented with choline was assessed. Live L. dumoffii bacteria cultured on the choline-supplemented medium induced TNF-α three-fold less efficiently than cells grown on the non-supplemented medium. There is an evident effect of PC modification, which impairs the macrophage inflammatory response.
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Aktas M, Danne L, Möller P, Narberhaus F. Membrane lipids in Agrobacterium tumefaciens: biosynthetic pathways and importance for pathogenesis. FRONTIERS IN PLANT SCIENCE 2014; 5:109. [PMID: 24723930 PMCID: PMC3972451 DOI: 10.3389/fpls.2014.00109] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/07/2014] [Indexed: 05/25/2023]
Abstract
Many cellular processes critically depend on the membrane composition. In this review, we focus on the biosynthesis and physiological roles of membrane lipids in the plant pathogen Agrobacterium tumefaciens. The major components of A. tumefaciens membranes are the phospholipids (PLs), phosphatidylethanolamine (PE), phosphatidylglycerol, phosphatidylcholine (PC) and cardiolipin, and ornithine lipids (OLs). Under phosphate-limited conditions, the membrane composition shifts to phosphate-free lipids like glycolipids, OLs and a betaine lipid. Remarkably, PC and OLs have opposing effects on virulence of A. tumefaciens. OL-lacking A. tumefaciens mutants form tumors on the host plant earlier than the wild type suggesting a reduced host defense response in the absence of OLs. In contrast, A. tumefaciens is compromised in tumor formation in the absence of PC. In general, PC is a rare component of bacterial membranes but amount to ~22% of all PLs in A. tumefaciens. PC biosynthesis occurs via two pathways. The phospholipid N-methyltransferase PmtA methylates PE via the intermediates monomethyl-PE and dimethyl-PE to PC. In the second pathway, the membrane-integral enzyme PC synthase (Pcs) condenses choline with CDP-diacylglycerol to PC. Apart from the virulence defect, PC-deficient A. tumefaciens pmtA and pcs double mutants show reduced motility, enhanced biofilm formation and increased sensitivity towards detergent and thermal stress. In summary, there is cumulative evidence that the membrane lipid composition of A. tumefaciens is critical for agrobacterial physiology and tumor formation.
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Affiliation(s)
| | | | | | - Franz Narberhaus
- *Correspondence: Franz Narberhaus, Microbial Biology, Department for Biology and Biotechnology, Ruhr University Bochum, Universitätsstrasse 150, NDEF 06/783, 44780 Bochum, Germany e-mail:
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Moser R, Aktas M, Narberhaus F. Phosphatidylcholine biosynthesis inXanthomonas campestrisvia a yeast-like acylation pathway. Mol Microbiol 2014; 91:736-50. [DOI: 10.1111/mmi.12492] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/10/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Roman Moser
- Microbial Biology; Ruhr University Bochum; Bochum Germany
| | - Meriyem Aktas
- Microbial Biology; Ruhr University Bochum; Bochum Germany
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Wargo MJ. Homeostasis and catabolism of choline and glycine betaine: lessons from Pseudomonas aeruginosa. Appl Environ Microbiol 2013; 79:2112-20. [PMID: 23354714 PMCID: PMC3623244 DOI: 10.1128/aem.03565-12] [Citation(s) in RCA: 113] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Most sequenced bacteria possess mechanisms to import choline and glycine betaine (GB) into the cytoplasm. The primary role of choline in bacteria appears to be as the precursor to GB, and GB is thought to primarily act as a potent osmoprotectant. Choline and GB may play accessory roles in shaping microbial communities, based on their limited availability and ability to enhance survival under stress conditions. Choline and GB enrichment near eukaryotes suggests a role in the chemical relationships between these two kingdoms, and some of these interactions have been experimentally demonstrated. While many bacteria can convert choline to GB for osmoprotection, a variety of soil- and water-dwelling bacteria have catabolic pathways for the multistep conversion of choline, via GB, to glycine and can thereby use choline and GB as sole sources of carbon and nitrogen. In these choline catabolizers, the GB intermediate represents a metabolic decision point to determine whether GB is catabolized or stored as an osmo- and stress protectant. This minireview focuses on this decision point in Pseudomonas aeruginosa, which aerobically catabolizes choline and can use GB as an osmoprotectant and a nutrient source. P. aeruginosa is an experimentally tractable and ecologically relevant model to study the regulatory pathways controlling choline and GB homeostasis in choline-catabolizing bacteria. The study of P. aeruginosa associations with eukaryotes and other bacteria also makes this a powerful model to study the impact of choline and GB, and their associated regulatory and catabolic pathways, on host-microbe and microbe-microbe relationships.
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Affiliation(s)
- Matthew J Wargo
- Department of Microbiology and Molecular Genetics and The Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, USA.
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13
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Fitzsimmons LF, Hampel KJ, Wargo MJ. Cellular choline and glycine betaine pools impact osmoprotection and phospholipase C production in Pseudomonas aeruginosa. J Bacteriol 2012; 194:4718-26. [PMID: 22753069 PMCID: PMC3415529 DOI: 10.1128/jb.00596-12] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 06/25/2012] [Indexed: 01/29/2023] Open
Abstract
Choline is abundantly produced by eukaryotes and plays an important role as a precursor of the osmoprotectant glycine betaine. In Pseudomonas aeruginosa, glycine betaine has additional roles as a nutrient source and an inducer of the hemolytic phospholipase C, PlcH. The multiple functions for glycine betaine suggested that the cytoplasmic pool of glycine betaine is regulated in P. aeruginosa. We used (13)C nuclear magnetic resonance ((13)C-NMR) to demonstrate that P. aeruginosa maintains both choline and glycine betaine pools under a variety of conditions, in contrast to the transient glycine betaine pool reported for most bacteria. We were able to experimentally manipulate the choline and glycine betaine pools by overexpression of the cognate catabolic genes. Depletion of either the choline or glycine betaine pool reduced phospholipase production, a result unexpected for choline depletion. Depletion of the glycine betaine pool, but not the choline pool, inhibited growth under conditions of high salt with glucose as the primary carbon source. Depletion of the choline pool inhibited growth under high-salt conditions with choline as the sole carbon source, suggesting a role for the choline pool under these conditions. Here we have described the presence of a choline pool in P. aeruginosa and other pseudomonads that, with the glycine betaine pool, regulates osmoprotection and phospholipase production and impacts growth under high-salt conditions. These findings suggest that the levels of both pools are actively maintained and that perturbation of either pool impacts P. aeruginosa physiology.
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Affiliation(s)
| | | | - Matthew J. Wargo
- Department of Microbiology and Molecular Genetics
- The Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont, USA
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14
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Geiger O, López-Lara IM, Sohlenkamp C. Phosphatidylcholine biosynthesis and function in bacteria. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:503-13. [PMID: 22922101 DOI: 10.1016/j.bbalip.2012.08.009] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 08/10/2012] [Accepted: 08/13/2012] [Indexed: 02/03/2023]
Abstract
Phosphatidylcholine (PC) is the major membrane-forming phospholipid in eukaryotes and is estimated to be present in about 15% of the domain Bacteria. Usually, PC can be synthesized in bacteria by either of two pathways, the phospholipid N-methylation (Pmt) pathway or the phosphatidylcholine synthase (Pcs) pathway. The three subsequent enzymatic methylations of phosphatidylethanolamine are performed by a single phospholipid N-methyltransferase in some bacteria whereas other bacteria possess multiple phospholipid N-methyltransferases each one performing one or several distinct methylation steps. Phosphatidylcholine synthase condenses choline directly with CDP-diacylglycerol to form CMP and PC. Like in eukaryotes, bacterial PC also functions as a biosynthetic intermediate during the formation of other biomolecules such as choline, diacylglycerol, or diacylglycerol-based phosphorus-free membrane lipids. Bacterial PC may serve as a specific recognition molecule but it affects the physicochemical properties of bacterial membranes as well. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Otto Geiger
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad s/n, Apdo. Postal 565-A, Cuernavaca, Morelos, CP62210, Mexico.
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