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Dramé I, Rossez Y, Krzewinski F, Charbonnel N, Ollivier-Nakusi L, Briandet R, Dague E, Forestier C, Balestrino D. FabR, a regulator of membrane lipid homeostasis, is involved in Klebsiella pneumoniae biofilm robustness. mBio 2024:e0131724. [PMID: 39240091 DOI: 10.1128/mbio.01317-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Accepted: 08/06/2024] [Indexed: 09/07/2024] Open
Abstract
Biofilm is a dynamic structure from which individual bacteria and micro-aggregates are released to subsequently colonize new niches by either detachment or dispersal. Screening of a transposon mutant library identified genes associated with the alteration of Klebsiella pneumoniae biofilm including fabR, which encodes a transcriptional regulator involved in membrane lipid homeostasis. An isogenic ∆fabR mutant formed more biofilm than the wild-type (WT) strain and its trans-complemented strain. The thick and round aggregates observed with ∆fabR were resistant to extensive washes, unlike those of the WT strain. Confocal microscopy and BioFlux microfluidic observations showed that fabR deletion was associated with biofilm robustness and impaired erosion over time. The genes fabB and yqfA associated with fatty acid metabolism were significantly overexpressed in the ∆fabR strain, in both planktonic and biofilm conditions. Two monounsaturated fatty acids, palmitoleic acid (C16:1) and oleic acid (C18:1), were found in higher proportion in biofilm cells than in planktonic forms, whereas heptadecenoic acid (C17:1) and octadecanoic acid, 11-methoxy (C18:0-OCH3) were found in higher proportion in the planktonic lifestyle. The fabR mutation induced variations in the fatty acid composition, with no clear differences in the amounts of saturated fatty acids (SFA) and unsaturated fatty acids for the planktonic lifestyle but lower SFA in the biofilm form. Atomic force microscopy showed that deletion of fabR is associated with decreased K. pneumoniae cell rigidity in the biofilm lifestyle, as well as a softer, more elastic biofilm with increased cell cohesion compared to the wild-type strain.IMPORTANCEKlebsiella pneumoniae is an opportunistic pathogen responsible for a wide range of nosocomial infections. The success of this pathogen is due to its high resistance to antibiotics and its ability to form biofilms. The molecular mechanisms involved in biofilm formation have been largely described but the dispersal process that releases individual and aggregate cells from mature biofilm is less well documented while it is associated with the colonization of new environments and thus new threats. Using a multidisciplinary approach, we show that modifications of bacterial membrane fatty acid composition lead to variations in the biofilm robustness, and subsequent bacterial detachment and biofilm erosion over time. These results enhance our understanding of the genetic requirements for biofilm formation in K. pneumoniae that affect the time course of biofilm development and the embrittlement step preceding its dispersal that will make it possible to control K. pneumoniae infections.
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Affiliation(s)
- Ibrahima Dramé
- Université Clermont Auvergne, CNRS, LMGE, Clermont-Ferrand, France
| | - Yannick Rossez
- Université Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, Lille, France
| | - Frederic Krzewinski
- Université Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, Lille, France
| | | | | | - Romain Briandet
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Etienne Dague
- LAAS-CNRS, CNRS, Univeristé de Toulouse, Toulouse, France
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Cronan JE. Unsaturated fatty acid synthesis in bacteria: Mechanisms and regulation of canonical and remarkably noncanonical pathways. Biochimie 2024; 218:137-151. [PMID: 37683993 PMCID: PMC10915108 DOI: 10.1016/j.biochi.2023.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 08/02/2023] [Accepted: 09/04/2023] [Indexed: 09/10/2023]
Abstract
Unsaturated phospholipid acyl chains are required for membrane function in most bacteria. The double bonds of the cis monoenoic chains arise by two distinct pathways depending on whether oxygen is required. The oxygen-independent pathway (traditionally called the anaerobic pathway) introduces the cis double bond by isomerization of the trans double bond intermediate of the fatty acid elongation cycle. Double bond isomerization occurs at an intermediate chain length (e.g., C10) and the isomerization product is elongated to the C16-C18 chains that become phospholipid monoenoic acyl chains. This pathway was first delineated in Escherichia coli and became the paradigm pathway. However, studies of other bacteria show deviations from this paradigm, the most exceptional being reversal of the fatty acid elongation cycle by a reaction paralleling the initial step in the β-oxidative degradation of fatty acids. In the oxygen-dependent pathway diiron enzymes called desaturases introduce a double bond into a saturated acyl chain by regioselective cis dehydrogenation through activation of molecular oxygen with an active-site diiron cluster. This difficult hydrogen abstraction from a methylene group often occurs at the midpoint of a saturated fatty acyl chain. In bacteria the acyl chain is a phospholipid acyl chain, and the desaturase is membrane bound. Both the oxygen-independent oxygen-dependent pathways are transcriptionally regulated by repressor and activator proteins that respond to small molecule ligands such as acyl-CoAs. However, in Bacillus subtilis the desaturase is synthesized only at low growth temperatures, a process controlled by a signal transduction regulatory pathway dependent on membrane lipid properties.
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Affiliation(s)
- John E Cronan
- Departments of Microbiology and Biochemistry, University of Illinois, Urbana, 61801, USA.
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3
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Dong H, Cronan JE. Suppressor mutants demonstrate the metabolic plasticity of unsaturated fatty acid synthesis in Pseudomonas aeruginosa PAO1. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001400. [PMID: 37818937 PMCID: PMC10634369 DOI: 10.1099/mic.0.001400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 10/03/2023] [Indexed: 10/13/2023]
Abstract
Pseudomonas aeruginosa PAO1 has two aerobic pathways for synthesis of unsaturated fatty acids (UFAs), DesA and DesB plus the oxygen independent FabAB pathway. The DesA desaturase acts on saturated acyl chains of membrane phospholipid bilayers whereas the substrates of the DesB desaturase are thought to be long chain saturated acyl-CoA thioesters derived from exogeneous saturated fatty acids that are required to support DesB-dependent growth. Under suitable aerobic conditions either of these membrane-bound desaturates can support growth of P. aeruginosa ∆fabA strains lacking the oxygen independent FabAB pathway. We previously studied function of the desA desaturase of P. putida in a P. aeruginosa ∆fabA ∆desA strain that required supplementation with a UFA for growth and noted bypass suppression of the P. aeruginosa ∆fabA ∆desA strain that restored UFA synthesis. We report three genes encoding lipid metabolism proteins that give rise to suppressor strains that bypass loss of the DesA and oxygen independent FabAB pathways.
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Affiliation(s)
- Huijuan Dong
- Departments of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - John E. Cronan
- Departments of Microbiology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
- Departments of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
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Wani SR, Dubey AA, Jain V. Ms6244 is a novel Mycobacterium smegmatis TetR family transcriptional repressor that regulates cell growth and morphophysiology. FEBS Lett 2023; 597:1428-1440. [PMID: 36694284 DOI: 10.1002/1873-3468.14582] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 01/02/2023] [Accepted: 01/04/2023] [Indexed: 01/26/2023]
Abstract
Transcriptional factors such as the TetR family of transcriptional regulators (TFTRs) are widely found amongst bacteria, including mycobacteria, and are accountable for their survival. Here, we characterized a novel TFTR, Ms6244, from Mycobacterium smegmatis that negatively autoregulates its expression and represses its neighbouring gene, Ms6243. We also report the binding of Ms6244 to the inverted repeats in the intergenic region of Ms6244 and Ms6243. Further, an Ms6244-deleted strain shows various morpho-physiological differences compared to the wild type. We further confirmed that the deletion of Ms6244 itself and not the resultant Ms6243 overexpression is the cause of the altered physiology. Our data thus suggest that Ms6244 is an essential regulator, having far-reaching effects on M. smegmatis physiology.
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Affiliation(s)
- Saloni Rajesh Wani
- Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Abhishek Anil Dubey
- Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
| | - Vikas Jain
- Microbiology and Molecular Biology Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research (IISER), Bhopal, India
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Contribution of Membrane Vesicle to Reprogramming of Bacterial Membrane Fluidity in Pseudomonas aeruginosa. mSphere 2022; 7:e0018722. [PMID: 35603537 PMCID: PMC9241526 DOI: 10.1128/msphere.00187-22] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen capable of resisting environmental insults by applying various strategies, including regulating membrane fluidity and producing membrane vesicles (MVs). This study examined the difference in membrane fluidity between planktonic and biofilm modes of growth in P. aeruginosa and whether the ability to alter membrane rigidity in P. aeruginosa could be transferred via MVs. To this end, planktonic and biofilm P. aeruginosa were compared with respect to the lipid composition of their membranes and their MVs and the expression of genes contributing to alteration of membrane fluidity. Additionally, viscosity maps of the bacterial membrane in planktonic and biofilm lifestyles and under the effect of incubation with bacterial MVs were obtained. Further, the growth rate and biofilm formation capability of P. aeruginosa in the presence of MVs were compared. Results showed that the membrane of the biofilm bacteria is significantly less fluid than the membrane of the planktonic bacteria and is enriched with saturated fatty acids. Moreover, the enzymes involved in altering the structure of existing lipids and favoring membrane rigidification are overexpressed in the biofilm bacteria. MVs of biofilm P. aeruginosa elicit membrane rigidification and delay the bacterial growth in the planktonic lifestyle; conversely, they enhance biofilm development in P. aeruginosa. Overall, the study describes the interplay between the planktonic and biofilm bacteria by shedding light on the role of MVs in altering membrane fluidity. IMPORTANCE Membrane rigidification is a survival strategy in Pseudomonas aeruginosa exposed to stress. Despite various studies dedicated to the mechanism behind this phenomenon, not much attention has been paid to the contribution of the bacterial membrane vesicles (MVs) in this regard. This study revealed that P. aeruginosa rigidifies its membrane in the biofilm mode of growth. Additionally, the capability of decreasing membrane fluidity is transferable to the bacterial population via the bacterial MVs, resulting in reprogramming of bacterial membrane fluidity. Given the importance of membrane rigidification for decreasing the pathogen’s susceptibility to antimicrobials, elucidation of the conditions leading to such biophysicochemical modulation of the P. aeruginosa membrane should be considered for the purpose of developing therapeutic approaches against this resistant pathogen.
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Cooper C, Peterson EJR, Bailo R, Pan M, Singh A, Moynihan P, Nakaya M, Fujiwara N, Baliga N, Bhatt A. MadR mediates acyl CoA-dependent regulation of mycolic acid desaturation in mycobacteria. Proc Natl Acad Sci U S A 2022; 119:e2111059119. [PMID: 35165190 PMCID: PMC8872791 DOI: 10.1073/pnas.2111059119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 12/28/2021] [Indexed: 11/20/2022] Open
Abstract
Mycobacterium tuberculosis has a lipid-rich cell envelope that is remodeled throughout infection to enable adaptation within the host. Few transcriptional regulators have been characterized that coordinate synthesis of mycolic acids, the major cell wall lipids of mycobacteria. Here, we show that the mycolic acid desaturase regulator (MadR), a transcriptional repressor of the mycolate desaturase genes desA1 and desA2, controls mycolic acid desaturation and biosynthesis in response to cell envelope stress. A madR-null mutant of M. smegmatis exhibited traits of an impaired cell wall with an altered outer mycomembrane, accumulation of a desaturated α-mycolate, susceptibility to antimycobacterials, and cell surface disruption. Transcriptomic profiling showed that enriched lipid metabolism genes that were significantly down-regulated upon madR deletion included acyl-coenzyme A (aceyl-CoA) dehydrogenases, implicating it in the indirect control of β-oxidation pathways. Electromobility shift assays and binding affinities suggest a unique acyl-CoA pool-sensing mechanism, whereby MadR is able to bind a range of acyl-CoAs, including those with unsaturated as well as saturated acyl chains. MadR repression of desA1/desA2 is relieved upon binding of saturated acyl-CoAs of chain length C16 to C24, while no impact is observed upon binding of shorter chain and unsaturated acyl-CoAs. We propose this mechanism of regulation as distinct to other mycolic acid and fatty acid synthesis regulators and place MadR as the key regulatory checkpoint that coordinates mycolic acid remodeling during infection in response to host-derived cell surface perturbation.
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Affiliation(s)
- Charlotte Cooper
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | | | - Rebeca Bailo
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | - Min Pan
- Institute for Systems Biology, Seattle, WA 98109
| | - Albel Singh
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | - Patrick Moynihan
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
| | | | - Nagatoshi Fujiwara
- Department of Food and Nutrition, Faculty of Contemporary Human Life Science, Tezukayama University, Nara 631-8585, Japan
| | - Nitin Baliga
- Institute for Systems Biology, Seattle, WA 98109;
- Department of Biology, University of Washington, Seattle, WA 98105
- Department of Microbiology, University of Washington, Seattle, WA 98105
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98105
- Lawrence Berkeley National Lab, Berkeley, CA 94720
| | - Apoorva Bhatt
- School of Biosciences, University of Birmingham, Birmingham B15 2TT, UK;
- Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
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Medeiros Filho F, do Nascimento APB, Costa MDOCE, Merigueti TC, de Menezes MA, Nicolás MF, Dos Santos MT, Carvalho-Assef APD, da Silva FAB. A Systematic Strategy to Find Potential Therapeutic Targets for Pseudomonas aeruginosa Using Integrated Computational Models. Front Mol Biosci 2021; 8:728129. [PMID: 34616771 PMCID: PMC8488468 DOI: 10.3389/fmolb.2021.728129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/31/2021] [Indexed: 12/26/2022] Open
Abstract
Pseudomonas aeruginosa is an opportunistic human pathogen that has been a constant global health problem due to its ability to cause infection at different body sites and its resistance to a broad spectrum of clinically available antibiotics. The World Health Organization classified multidrug-resistant Pseudomonas aeruginosa among the top-ranked organisms that require urgent research and development of effective therapeutic options. Several approaches have been taken to achieve these goals, but they all depend on discovering potential drug targets. The large amount of data obtained from sequencing technologies has been used to create computational models of organisms, which provide a powerful tool for better understanding their biological behavior. In the present work, we applied a method to integrate transcriptome data with genome-scale metabolic networks of Pseudomonas aeruginosa. We submitted both metabolic and integrated models to dynamic simulations and compared their performance with published in vitro growth curves. In addition, we used these models to identify potential therapeutic targets and compared the results to analyze the assumption that computational models enriched with biological measurements can provide more selective and (or) specific predictions. Our results demonstrate that dynamic simulations from integrated models result in more accurate growth curves and flux distribution more coherent with biological observations. Moreover, identifying drug targets from integrated models is more selective as the predicted genes were a subset of those found in the metabolic models. Our analysis resulted in the identification of 26 non-host homologous targets. Among them, we highlighted five top-ranked genes based on lesser conservation with the human microbiome. Overall, some of the genes identified in this work have already been proposed by different approaches and (or) are already investigated as targets to antimicrobial compounds, reinforcing the benefit of using integrated models as a starting point to selecting biologically relevant therapeutic targets.
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8
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Velázquez-Sánchez C, Vences-Guzmán MÁ, Moreno S, Tinoco-Valencia R, Espín G, Guzmán J, Sahonero-Canavesi DX, Sohlenkamp C, Segura D. PsrA positively regulates the unsaturated fatty acid synthesis operon fabAB in Azotobacter vinelandii. Microbiol Res 2021; 249:126775. [PMID: 33964629 DOI: 10.1016/j.micres.2021.126775] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 03/12/2021] [Accepted: 04/27/2021] [Indexed: 10/21/2022]
Abstract
In Pseudomonas spp. PsrA, a transcriptional activator of the rpoS gene, regulates fatty acid catabolism by repressing the fadBA5 β-oxidation operon. In Azotobacter vinelandii, a soil bacterium closely related to Pseudomonas species, PsrA is also an activator of rpoS expression, although its participation in the regulation of lipid metabolism has not been analyzed. In this work we found that inactivation of psrA had no effect on the expression of β-oxidation genes in this bacterium, but instead decreased expression of the unsaturated fatty acid biosynthetic operon fabAB (3-hydroxydecanoyl-ACP dehydratase/isomerase and 3-ketoacyl-ACP synthase I). This inactivation also reduced the unsaturated fatty acid content, as revealed by the thin-layer chromatographic analysis, and confirmed by gas chromatography; notably, there was also a lower content of cyclopropane fatty acids, which are synthesized from unsaturated fatty acids. The absence of PsrA has no effect on the growth rate, but showed loss of cell viability during long-term growth, in accordance with the role of these unsaturated and cyclopropane fatty acids in the protection of membranes. Finally, an electrophoretic mobility shift assay revealed specific binding of PsrA to the fabA promoter region, where a putative binding site for this regulator was located. Taken together, our data show that PsrA plays an important role in the regulation of unsaturated fatty acids metabolism in A. vinelandii by positively regulating fabAB.
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Affiliation(s)
- Claudia Velázquez-Sánchez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | | | - Soledad Moreno
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Raunel Tinoco-Valencia
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Guadalupe Espín
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Josefina Guzmán
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | | | - Christian Sohlenkamp
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Daniel Segura
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
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Pan X, Fan Z, Chen L, Liu C, Bai F, Wei Y, Tian Z, Dong Y, Shi J, Chen H, Jin Y, Cheng Z, Jin S, Lin J, Wu W. PvrA is a novel regulator that contributes to Pseudomonas aeruginosa pathogenesis by controlling bacterial utilization of long chain fatty acids. Nucleic Acids Res 2020; 48:5967-5985. [PMID: 32406921 PMCID: PMC7293031 DOI: 10.1093/nar/gkaa377] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 04/28/2020] [Accepted: 04/30/2020] [Indexed: 12/19/2022] Open
Abstract
During infection of a host, Pseudomonas aeruginosa orchestrates global gene expression to adapt to the host environment and counter the immune attacks. P. aeruginosa harbours hundreds of regulatory genes that play essential roles in controlling gene expression. However, their contributions to the bacterial pathogenesis remain largely unknown. In this study, we analysed the transcriptomic profile of P. aeruginosa cells isolated from lungs of infected mice and examined the roles of upregulated regulatory genes in bacterial virulence. Mutation of a novel regulatory gene pvrA (PA2957) attenuated the bacterial virulence in an acute pneumonia model. Chromatin immunoprecipitation (ChIP)-Seq and genetic analyses revealed that PvrA directly regulates genes involved in phosphatidylcholine utilization and fatty acid catabolism. Mutation of the pvrA resulted in defective bacterial growth when phosphatidylcholine or palmitic acid was used as the sole carbon source. We further demonstrated that palmitoyl coenzyme A is a ligand for the PvrA, enhancing the binding affinity of PvrA to its target promoters. An arginine residue at position 136 was found to be essential for PvrA to bind palmitoyl coenzyme A. Overall, our results revealed a novel regulatory pathway that controls genes involved in phosphatidylcholine and fatty acid utilization and contributes to the bacterial virulence.
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Affiliation(s)
- Xiaolei Pan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zheng Fan
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Lei Chen
- Department of Plant Biology and Ecology, College of Life Science Nankai University, Tianjin 300071 China
| | - Chang Liu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Fang Bai
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yu Wei
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, China
| | - Zhenyang Tian
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yuanyuan Dong
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Jing Shi
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Hao Chen
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Yongxin Jin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Zhihui Cheng
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
| | - Shouguang Jin
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Jianping Lin
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
- State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Tianjin 300071, China
| | - Weihui Wu
- State Key Laboratory of Medicinal Chemical Biology, Key Laboratory of Molecular Microbiology and Technology of the Ministry of Education, Department of Microbiology, College of Life Sciences, Nankai University, Tianjin 300071, China
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10
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Allemann MN, Allen EE. Genetic regulation of the bacterial omega-3 polyunsaturated fatty acid biosynthesis pathway. J Bacteriol 2020; 202:JB.00050-20. [PMID: 32513681 PMCID: PMC8404712 DOI: 10.1128/jb.00050-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 05/28/2020] [Indexed: 02/07/2023] Open
Abstract
A characteristic among many marine Gammaproteobacteria is the biosynthesis and incorporation of omega-3 polyunsaturated fatty acids into membrane phospholipids. The biosynthesis of eicosapentaenoic (EPA) and/or docosahexaenoic (DHA) acids is mediated by a polyketide/fatty acid synthase mechanism encoded by a set of five genes, pfaABCDE. This unique fatty acid synthesis pathway co-exists with the principal type II dissociated fatty acid synthesis pathway, which is responsible for the biosynthesis of core saturated, monounsaturated, and hydroxylated fatty acids used in phospholipid and lipid A biosynthesis. In this work, a genetic approach was undertaken to elucidate genetic regulation of the pfa genes in the model marine bacterium Photobacterium profundum SS9. Using a reporter gene fusion, we showed that expression of the pfa operon is down regulated in response to exogenous fatty acids, particularly long chain monounsaturated fatty acids. This regulation occurs independently of the canonical fatty acid regulators, FabR and FadR, present in P. profundum SS9. Transposon mutagenesis and screening of a library of mutants identified a novel transcriptional regulator, which we have designated pfaF, to be responsible for the observed regulation of the pfa operon in P. profundum SS9. Gel mobility shift and DNase I footprinting assays confirmed that PfaF binds the pfaA promoter and identified the PfaF binding site.Importance The production of long-chain omega-3 polyunsaturated fatty acids (PUFA) by marine Gammaproteobacteria, particularly those from deep-sea environments, has been known for decades. These unique fatty acids are produced by a polyketide-type mechanism and subsequently incorporated into the phospholipid membrane. While much research has focused on the biosynthesis genes, their products and the phylogenetic distribution of these gene clusters, no prior studies have detailed the genetic regulation of this pathway. This study describes how this pathway is regulated under various culture conditions and has identified and characterized a fatty acid responsive transcriptional regulator specific to PUFA biosynthesis.
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Affiliation(s)
- Marco N Allemann
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA USA
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA USA
| | - Eric E Allen
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA USA
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA USA
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA USA
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11
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Murarka P, Srivastava P. Characterization of DNA binding and ligand binding properties of the TetR family protein involved in regulation of dsz operon in Gordonia sp. IITR100. Int J Biol Macromol 2019; 141:671-679. [PMID: 31493456 DOI: 10.1016/j.ijbiomac.2019.09.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 08/13/2019] [Accepted: 09/03/2019] [Indexed: 01/03/2023]
Abstract
Gordonia sp. IITR100 is a biodesulfurizing bacterium which can metabolize dibenzothiophene (DBT) to 2 hydroxybiphenyl in four steps via the 4S pathway. The genes involved in the metabolism are present in the form of an operon, dszABC, which gets activated by a TetR family protein. Here, we report the detailed characterization of the DNA binding and ligand binding property of the TetR family protein. The protein was found to be conserved across other desulfurizing organisms. The protein was purified and was found to exist as dimer. The presence of ligand binding site was identified by docking studies and the structural changes in the protein upon ligand binding were determined by CD spectroscopy and tryptophan fluorescence. Further, it was determined that this protein binds to an imperfect palindromic DNA sequence present in the dsz promoter DNA. Binding to the DNA also changes conformation of the protein.
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Affiliation(s)
- Pooja Murarka
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Preeti Srivastava
- Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
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12
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Yang H, Zhao C, Tang MC, Wang Y, Wang SP, Allard P, Furtos A, Mitchell GA. Inborn errors of mitochondrial acyl-coenzyme a metabolism: acyl-CoA biology meets the clinic. Mol Genet Metab 2019; 128:30-44. [PMID: 31186158 DOI: 10.1016/j.ymgme.2019.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/30/2019] [Accepted: 05/05/2019] [Indexed: 12/18/2022]
Abstract
The last decade saw major advances in understanding the metabolism of Coenzyme A (CoA) thioesters (acyl-CoAs) and related inborn errors (CoA metabolic diseases, CAMDs). For diagnosis, acylcarnitines and organic acids, both derived from acyl-CoAs, are excellent markers of most CAMDs. Clinically, each CAMD is unique but strikingly, three main patterns emerge: first, systemic decompensations with combinations of acidosis, ketosis, hypoglycemia, hyperammonemia and fatty liver; second, neurological episodes, particularly acute "stroke-like" episodes, often involving the basal ganglia but sometimes cerebral cortex, brainstem or optic nerves and third, especially in CAMDs of long chain fatty acyl-CoA metabolism, lipid myopathy, cardiomyopathy and arrhythmia. Some patients develop signs from more than one category. The pathophysiology of CAMDs is not precisely understood. Available data suggest that signs may result from CoA sequestration, toxicity and redistribution (CASTOR) in the mitochondrial matrix has been suggested to play a role. This predicts that most CAMDs cause deficiency of CoA, limiting mitochondrial energy production, and that toxic effects from the abnormal accumulation of acyl-CoAs and from extramitochondrial functions of acetyl-CoA may also contribute. Recent progress includes the following. (1) Direct measurements of tissue acyl-CoAs in mammalian models of CAMDs have been related to clinical features. (2) Inborn errors of CoA biosynthesis were shown to cause clinical changes similar to those of inborn errors of acyl-CoA degradation. (3) CoA levels in cells can be influenced pharmacologically. (4) Roles for acetyl-CoA are increasingly identified in all cell compartments. (5) Nonenzymatic acyl-CoA-mediated acylation of intracellular proteins occurs in mammalian tissues and is increased in CAMDs.
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Affiliation(s)
- Hao Yang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Canada
| | - Chen Zhao
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Canada; College of Animal Science and Technology, Northwest A&F University, China
| | | | - Youlin Wang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Canada
| | - Shu Pei Wang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Canada
| | - Pierre Allard
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Canada
| | | | - Grant A Mitchell
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Canada.
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13
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Le Sénéchal C, Crouzet M, Costaglioli P, Barthe C, Buré C, Vilain S. Phospholipid Content of Pseudomonas aeruginosa PAO1 Is Modulated by the Growth Phase Rather Than the Immobilization State. Lipids 2019; 54:519-529. [PMID: 31397925 DOI: 10.1002/lipd.12184] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 07/15/2019] [Accepted: 07/16/2019] [Indexed: 11/11/2022]
Abstract
Biofilms have significance in medical, industrial, and environmental settings, and can cause important damage. As biofilms are tolerant to various stresses, including antibiotics, it is necessary to better understand their formation. For this reason, we characterized the phospholipidome of Pseudomonas aeruginosa, an opportunistic pathogen involved in numerous infections, during the first steps of the biofilm development. By a liquid chromatography-tandem mass spectrometry time-course analysis over a 24-h period, we compared the phospholipid (PL) composition of immobilized (attached) and planktonic (unattached) P. aeruginosa PAO1 cells. Our results showed that the PL content of P. aeruginosa PAO1 was mainly modulated by the incubation time, thus related to bacterial growth but also, more modestly, by the immobilization state. We observed that relative amounts of PL varied over time with two main profiles and that these profiles are correlated to its fatty acid composition, including the degree of unsaturation. A statistical analysis revealed that the PL contents of both attached and unattached PAO1 cells were significantly different mainly after 3 and 6 h of incubation and that the amounts of two PL presented a statistical difference between attached and unattached cells all along the 24-h period: PtdEtn 16:0_18:1 and PtdEtn 18:1_18:1.
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Affiliation(s)
| | - Marc Crouzet
- CBMN, University of Bordeaux, UMR 5248, F-33600, Pessac, France
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14
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Peterson EJ, Bailo R, Rothchild AC, Arrieta-Ortiz ML, Kaur A, Pan M, Mai D, Abidi AA, Cooper C, Aderem A, Bhatt A, Baliga NS. Path-seq identifies an essential mycolate remodeling program for mycobacterial host adaptation. Mol Syst Biol 2019; 15:e8584. [PMID: 30833303 PMCID: PMC6398593 DOI: 10.15252/msb.20188584] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 01/31/2019] [Accepted: 02/04/2019] [Indexed: 11/23/2022] Open
Abstract
The success of Mycobacterium tuberculosis (MTB) stems from its ability to remain hidden from the immune system within macrophages. Here, we report a new technology (Path-seq) to sequence miniscule amounts of MTB transcripts within up to million-fold excess host RNA Using Path-seq and regulatory network analyses, we have discovered a novel transcriptional program for in vivo mycobacterial cell wall remodeling when the pathogen infects alveolar macrophages in mice. We have discovered that MadR transcriptionally modulates two mycolic acid desaturases desA1/desA2 to initially promote cell wall remodeling upon in vitro macrophage infection and, subsequently, reduces mycolate biosynthesis upon entering dormancy. We demonstrate that disrupting MadR program is lethal to diverse mycobacteria making this evolutionarily conserved regulator a prime antitubercular target for both early and late stages of infection.
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Affiliation(s)
| | - Rebeca Bailo
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Alissa C Rothchild
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | | | | | - Min Pan
- Institute for Systems Biology, Seattle, WA, USA
| | - Dat Mai
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | | | - Charlotte Cooper
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Alan Aderem
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Apoorva Bhatt
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | - Nitin S Baliga
- Institute for Systems Biology, Seattle, WA, USA
- Molecular and Cellular Biology Program, Departments of Microbiology and Biology, University of Washington, Seattle, WA, USA
- Lawrence Berkeley National Laboratories, Berkeley, CA, USA
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15
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Heredia RM, Lucchesi GI. Pseudomonas putida Δ9-fatty acid desaturase: Gene cloning, expression, and function in the cationic surfactants stress. J Basic Microbiol 2019; 59:525-534. [PMID: 30779369 DOI: 10.1002/jobm.201800595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 01/07/2019] [Accepted: 01/13/2019] [Indexed: 11/06/2022]
Abstract
Pseudomonas putida counteract the fluidizing effect of cationic surfactants decreasing the content of membrane unsaturated fatty acid (UFA). A Δ9-fatty acid desaturase gene (desA) from P. putida was isolated, cloned, and successfully expressed in Escherichia coli, a Δ9 desaturase deficient organism. desA consists of 1185 bp and codes for 394 amino acids. The deduced amino acid sequence reveals three histidine clusters and a hydropathy profile, typical of membrane-bound desaturases. Validating desA expression in E. coli cells, the amount of palmitoleic acid increased from 2.05 to 7.36%, with the concomitant increase in membrane fluidity (fluorescence polarization value decrease from 0.13 ± 0.03 to 0.09 ± 0.02). Also, when DesA activity was assayed in vivo, the percentage of UFA obtained from exogenous palmitic acid [1-14 C] increased 10-fold. In contrast, when cells expressing desA were exposed 15 min at sublethal concentration of cationic surfactants, the amount of UFA was 82% lower than that detected in cells non-exposed. Thus, the decrease in UFA content to counteract the fluidizing effect of cationic surfactants can be correlated with reduction of DesA activity.
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Affiliation(s)
- Romina M Heredia
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
| | - Gloria I Lucchesi
- Departamento de Biología Molecular, Facultad de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina
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16
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Gao R, Li D, Lin Y, Lin J, Xia X, Wang H, Bi L, Zhu J, Hassan B, Wang S, Feng Y. Structural and Functional Characterization of the FadR Regulatory Protein from Vibrio alginolyticus. Front Cell Infect Microbiol 2017; 7:513. [PMID: 29312893 PMCID: PMC5733061 DOI: 10.3389/fcimb.2017.00513] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/29/2017] [Indexed: 02/03/2023] Open
Abstract
The structure of Vibrio cholerae FadR (VcFadR) complexed with the ligand oleoyl-CoA suggests an additional ligand-binding site. However, the fatty acid metabolism and its regulation is poorly addressed in Vibrio alginolyticus, a species closely-related to V. cholerae. Here, we show crystal structures of V. alginolyticus FadR (ValFadR) alone and its complex with the palmitoyl-CoA, a long-chain fatty acyl ligand different from the oleoyl-CoA occupied by VcFadR. Structural comparison indicates that both VcFadR and ValFadR consistently have an additional ligand-binding site (called site 2), which leads to more dramatic conformational-change of DNA-binding domain than that of the E. coli FadR (EcFadR). Isothermal titration calorimetry (ITC) analyses defines that the ligand-binding pattern of ValFadR (2:1) is distinct from that of EcFadR (1:1). Together with surface plasmon resonance (SPR), electrophoresis mobility shift assay (EMSA) demonstrates that ValFadR binds fabA, an important gene of unsaturated fatty acid (UFA) synthesis. The removal of fadR from V. cholerae attenuates fabA transcription and results in the unbalance of UFA/SFA incorporated into membrane phospholipids. Genetic complementation of the mutant version of fadR (Δ42, 136-177) lacking site 2 cannot restore the defective phenotypes of ΔfadR while the wild-type fadR gene and addition of exogenous oleate can restore them. Mice experiments reveals that VcFadR and its site 2 have roles in bacterial colonizing. Together, the results might represent an additional example that illustrates the Vibrio FadR-mediated lipid regulation and its role in pathogenesis.
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Affiliation(s)
- Rongsui Gao
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, China
| | - Defeng Li
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yuan Lin
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jingxia Lin
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaoyun Xia
- Department of Microbiology, Nanjing Agricultural University, Nanjing, China
| | - Hui Wang
- Department of Microbiology, Nanjing Agricultural University, Nanjing, China
| | - Lijun Bi
- Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jun Zhu
- Department of Microbiology, Nanjing Agricultural University, Nanjing, China.,Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Bachar Hassan
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States
| | - Shihua Wang
- School of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Youjun Feng
- Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, Hangzhou, China
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17
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Di Capua CB, Doprado M, Belardinelli JM, Morbidoni HR. Complete auxotrophy for unsaturated fatty acids requires deletion of two sets of genes in Mycobacterium smegmatis. Mol Microbiol 2017; 106:93-108. [PMID: 28762586 DOI: 10.1111/mmi.13753] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2017] [Indexed: 11/29/2022]
Abstract
The synthesis of unsaturated fatty acids in Mycobacterium smegmatis is poorly characterized. Bioinformatic analysis revealed four putative fatty acid desaturases in its genome, one of which, MSMEG_1886, is highly homologous to desA3, the only palmitoyl/stearoyl desaturase present in the Mycobacterium tuberculosis genome. A MSMEG_1886 deletion mutant was partially auxotrophic for oleic acid and viable at 37°C and 25°C, although with a long lag phase in liquid medium. Fatty acid analysis suggested that MSMEG_1886 is a palmitoyl/stearoyl desaturase, as the synthesis of palmitoleic acid was abrogated, while oleic acid contents dropped by half in the mutant. Deletion of the operon MSMEG_1741-1743 (highly homologous to a Pseudomonas aeruginosa acyl-CoA desaturase) had little effect on growth of the parental strain; however the double mutant MSMEG_1886-MSMEG_1741-1743 strictly required oleic acid for growth. The ΔMSMEG_1886-ΔMSMEG_1741 double mutant was able to grow (poorly but better than the ΔMSMEG_1886 single mutant) in solid and liquid media devoid of oleic acid, suggesting a repressor role for ΔMSMEG_1741. Fatty acid analysis of the described mutants suggested that MSMEG_1742-43 desaturates C18:0 and C24:0 fatty acids. Thus, although the M. smegmatis desA3 homologue is the major player in unsaturated fatty acid synthesis, a second set of genes is also involved.
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Affiliation(s)
- Cecilia B Di Capua
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Mariana Doprado
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Juan Manuel Belardinelli
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Héctor R Morbidoni
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
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18
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19
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Albanesi D, de Mendoza D. FapR: From Control of Membrane Lipid Homeostasis to a Biotechnological Tool. Front Mol Biosci 2016; 3:64. [PMID: 27766255 PMCID: PMC5052256 DOI: 10.3389/fmolb.2016.00064] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 09/21/2016] [Indexed: 01/22/2023] Open
Abstract
Phospholipids and fatty acids are not only one of the major components of cell membranes but also important metabolic intermediates in bacteria. Since the fatty acid biosynthetic pathway is essential and energetically expensive, organisms have developed a diversity of homeostatic mechanisms to fine-tune the concentration of lipids at particular levels. FapR is the first global regulator of lipid synthesis discovered in bacteria and is largely conserved in Gram-positive organisms including important human pathogens, such as Staphylococcus aureus, Bacillus anthracis, and Listeria monocytogenes. FapR is a transcription factor that negatively controls the expression of several genes of the fatty acid and phospholipid biosynthesis and was first identified in Bacillus subtilis. This review focuses on the genetic, biochemical and structural advances that led to a detailed understanding of lipid homeostasis control by FapR providing unique opportunities to learn how Gram-positive bacteria monitor the status of fatty acid biosynthesis and adjust the lipid synthesis accordingly. Furthermore, we also cover the potential of the FapR system as a target for new drugs against Gram-positive bacteria as well as its recent biotechnological applications in diverse organisms.
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Affiliation(s)
- Daniela Albanesi
- Laboratorio de Fisiología Microbiana, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Rosario Rosario, Argentina
| | - Diego de Mendoza
- Laboratorio de Fisiología Microbiana, Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad Nacional de Rosario Rosario, Argentina
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20
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Abstract
The pathways in Escherichia coli and (largely by analogy) S. enterica remain the paradigm of bacterial lipid synthetic pathways, although recently considerable diversity among bacteria in the specific areas of lipid synthesis has been demonstrated. The structural biology of the fatty acid synthetic proteins is essentially complete. However, the membrane-bound enzymes of phospholipid synthesis remain recalcitrant to structural analyses. Recent advances in genetic technology have allowed the essentialgenes of lipid synthesis to be tested with rigor, and as expected most genes are essential under standard growth conditions. Conditionally lethal mutants are available in numerous genes, which facilitates physiological analyses. The array of genetic constructs facilitates analysis of the functions of genes from other organisms. Advances in mass spectroscopy have allowed very accurate and detailed analyses of lipid compositions as well as detection of the interactions of lipid biosynthetic proteins with one another and with proteins outside the lipid pathway. The combination of these advances has resulted in use of E. coli and S. enterica for discovery of new antimicrobials targeted to lipid synthesis and in deciphering the molecular actions of known antimicrobials. Finally,roles for bacterial fatty acids other than as membrane lipid structural components have been uncovered. For example, fatty acid synthesis plays major roles in the synthesis of the essential enzyme cofactors, biotin and lipoic acid. Although other roles for bacterial fatty acids, such as synthesis of acyl-homoserine quorum-sensing molecules, are not native to E. coli introduction of the relevant gene(s) synthesis of these foreign molecules readily proceeds and the sophisticated tools available can used to decipher the mechanisms of synthesis of these molecules.
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21
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Kondakova T, D'Heygère F, Feuilloley MJ, Orange N, Heipieper HJ, Duclairoir Poc C. Glycerophospholipid synthesis and functions in Pseudomonas. Chem Phys Lipids 2015; 190:27-42. [PMID: 26148574 DOI: 10.1016/j.chemphyslip.2015.06.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/29/2015] [Accepted: 06/30/2015] [Indexed: 11/25/2022]
Abstract
The genus Pseudomonas is one of the most heterogeneous groups of eubacteria, presents in all major natural environments and in wide range of associations with plants and animals. The wide distribution of these bacteria is due to the use of specific mechanisms to adapt to environmental modifications. Generally, bacterial adaptation is only considered under the aspect of genes and protein expression, but lipids also play a pivotal role in bacterial functioning and homeostasis. This review resumes the mechanisms and regulations of pseudomonal glycerophospholipid synthesis, and the roles of glycerophospholipids in bacterial metabolism and homeostasis. Recently discovered specific pathways of P. aeruginosa lipid synthesis indicate the lineage dependent mechanisms of fatty acids homeostasis. Pseudomonas glycerophospholipids ensure structure functions and play important roles in bacterial adaptation to environmental modifications. The lipidome of Pseudomonas contains a typical eukaryotic glycerophospholipid--phosphatidylcholine -, which is involved in bacteria-host interactions. The ability of Pseudomonas to exploit eukaryotic lipids shows specific and original strategies developed by these microorganisms to succeed in their infectious process. All compiled data provide the demonstration of the importance of studying the Pseudomonas lipidome to inhibit the infectious potential of these highly versatile germs.
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Affiliation(s)
- Tatiana Kondakova
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France
| | - François D'Heygère
- Centre de Biophysique Moléculaire, CNRS, UPR4301, rue Charles Sadron, 45071 Orléans, France
| | - Marc J Feuilloley
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France
| | - Nicole Orange
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France
| | - Hermann J Heipieper
- Department of Environmental Biotechnology, UFZ Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany
| | - Cécile Duclairoir Poc
- Normandie University of Rouen, Laboratory of Microbiology Signals and Microenvironment (LMSM), EA 4312, 55 rue St. Germain, 27000 Evreux, France.
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22
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Luo Q, Shi M, Ren Y, Gao H. Transcription factors FabR and FadR regulate both aerobic and anaerobic pathways for unsaturated fatty acid biosynthesis in Shewanella oneidensis. Front Microbiol 2014; 5:736. [PMID: 25566241 PMCID: PMC4273635 DOI: 10.3389/fmicb.2014.00736] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 12/05/2014] [Indexed: 01/01/2023] Open
Abstract
As genes for type II fatty acid synthesis are essential to the growth of Escherichia coli, its sole (anaerobic) pathway has significant potential as a target for novel antibacterial drug, and has been extensively studied. Despite this, we still know surprisingly little about fatty acid synthesis in bacteria because this anaerobic pathway in fact is not widely distributed. In this study, we show a novel model of unsaturated fatty acid (UFA) synthesis in Shewanella, emerging human pathogens in addition to well-known metal reducers. We identify both anaerobic and aerobic UFA biosynthesis pathways in the representative species, S. oneidensis. Uniquely, the bacterium also contains two regulators FabR and FadR, whose counterparts in other bacteria control the anaerobic pathway. However, we show that in S. oneidensis these two regulators are involved in regulation of both pathways, in either direct or indirect manner. Overall, our results indicate that the UFA biosynthesis and its regulation are far more complex than previously expected, and S. oneidensis serves as a good research model for further work.
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Affiliation(s)
- Qixia Luo
- Institute of Microbiology and College of Life Sciences, Zhejiang University Hangzhou, China
| | - Miaomiao Shi
- Institute of Microbiology and College of Life Sciences, Zhejiang University Hangzhou, China
| | - Yedan Ren
- Institute of Microbiology and College of Life Sciences, Zhejiang University Hangzhou, China
| | - Haichun Gao
- Institute of Microbiology and College of Life Sciences, Zhejiang University Hangzhou, China
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23
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Bhukya H, Bhujbalrao R, Bitra A, Anand R. Structural and functional basis of transcriptional regulation by TetR family protein CprB from S. coelicolor A3(2). Nucleic Acids Res 2014; 42:10122-33. [PMID: 25092919 PMCID: PMC4150764 DOI: 10.1093/nar/gku587] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Antibiotic production and resistance pathways in Streptomyces are dictated by the interplay of transcriptional regulatory proteins that trigger downstream responses via binding to small diffusible molecules. To decipher the mode of DNA binding and the associated allosteric mechanism in the sub-class of transcription factors that are induced by γ-butyrolactones, we present the crystal structure of CprB in complex with the consensus DNA element to a resolution of 3.25 Å. Binding of the DNA results in the restructuring of the dimeric interface of CprB, inducing a pendulum-like motion of the helix-turn-helix motif that inserts into the major groove. The crystal structure revealed that, CprB is bound to DNA as a dimer of dimers with the mode of binding being analogous to the broad spectrum multidrug transporter protein QacR from the antibiotic resistant strain Staphylococcus aureus. It was demonstrated that the CprB displays a cooperative mode of DNA binding, following a clamp and click model. Experiments performed on a subset of DNA sequences from Streptomyces coelicolor A3(2) suggest that CprB is most likely a pleiotropic regulator. Apart from serving as an autoregulator, it is potentially a part of a network of proteins that modulates the γ-butyrolactone synthesis and antibiotic regulation pathways in S. coelicolor A3(2).
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Affiliation(s)
- Hussain Bhukya
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India IITB-Monash Research Academy, Mumbai 400076, Maharashtra, India
| | - Ruchika Bhujbalrao
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
| | - Aruna Bitra
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
| | - Ruchi Anand
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, Maharashtra, India
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Abstract
The most common prokaryotic signal transduction mechanisms are the one-component systems in which a single polypeptide contains both a sensory domain and a DNA-binding domain. Among the >20 classes of one-component systems, the TetR family of regulators (TFRs) are widely associated with antibiotic resistance and the regulation of genes encoding small-molecule exporters. However, TFRs play a much broader role, controlling genes involved in metabolism, antibiotic production, quorum sensing, and many other aspects of prokaryotic physiology. There are several well-established model systems for understanding these important proteins, and structural studies have begun to unveil the mechanisms by which they bind DNA and recognize small-molecule ligands. The sequences for more than 200,000 TFRs are available in the public databases, and genomics studies are identifying their target genes. Three-dimensional structures have been solved for close to 200 TFRs. Comparison of these structures reveals a common overall architecture of nine conserved α helices. The most important open question concerning TFR biology is the nature and diversity of their ligands and how these relate to the biochemical processes under their control.
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25
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Fujihashi M, Nakatani T, Hirooka K, Matsuoka H, Fujita Y, Miki K. Structural characterization of a ligand-bound form of Bacillus subtilis FadR involved in the regulation of fatty acid degradation. Proteins 2014; 82:1301-10. [PMID: 24356978 DOI: 10.1002/prot.24496] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 11/28/2013] [Accepted: 12/09/2013] [Indexed: 11/05/2022]
Abstract
Bacillus subtilis FadR (FadR(Bs)), a member of the TetR family of bacterial transcriptional regulators, represses five fad operons including 15 genes, most of which are involved in β-oxidation of fatty acids. FadR(Bs) binds to the five FadR(Bs) boxes in the promoter regions and the binding is specifically inhibited by long-chain (C14-C20 ) acyl-CoAs, causing derepression of the fad operons. To elucidate the structural mechanism of this regulator, we have determined the crystal structures of FadR(Bs) proteins prepared with and without stearoyl(C18)-CoA. The crystal structure without adding any ligand molecules unexpectedly includes one small molecule, probably dodecyl(C12)-CoA derived from the Escherichia coli host, in its homodimeric structure. Also, we successfully obtained the structure of the ligand-bound form of the FadR(Bs) dimer by co-crystallization, in which two stearoyl-CoA molecules are accommodated, with the binding mode being essentially equivalent to that of dodecyl-CoA. Although the acyl-chain-binding cavity of FadR(Bs) is mainly hydrophobic, a hydrophilic patch encompasses the C1-C10 carbons of the acyl chain. This accounts for the previous report that the DNA binding of FadR(Bs) is specifically inhibited by the long-chain acyl-CoAs but not by the shorter ones. Structural comparison of the ligand-bound and unliganded subunits of FadR(Bs) revealed three regions around residues 21-31, 61-76, and 106-119 that were substantially changed in response to the ligand binding, and particularly with respect to the movements of Leu108 and Arg109. Site-directed mutagenesis of these residues revealed that Arg109, but not Leu108, is a key residue for maintenance of the DNA-binding affinity of FadR(Bs).
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Affiliation(s)
- Masahiro Fujihashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
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26
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Cuthbertson L, Ahn SK, Nodwell JR. Deglycosylation as a mechanism of inducible antibiotic resistance revealed using a global relational tree for one-component regulators. ACTA ACUST UNITED AC 2013; 20:232-40. [PMID: 23438752 DOI: 10.1016/j.chembiol.2012.11.011] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Revised: 11/22/2012] [Accepted: 11/27/2012] [Indexed: 10/27/2022]
Abstract
The ligands that interact with the vast majority of small-molecule binding transcription factors are unknown, a significant gap in our understanding of sensory perception by cells. TetR-family regulators (TFRs) are found in most prokaryotes and are involved in regulating virtually every aspect of prokaryotic life however only a few TFRs have been characterized. We report the application of phylogenomics to the identification of cognate ligands for TFRs. Using phylogenomics we identify a TFR, KijR, that responds to the antibiotic kijanimicin. We go on to show that KijR represses a gene, kijX, which confers resistance to kijanimicin. Finally we show that KijX inactivates kijanimicin by the hydrolytic removal of sugar residues. This is a demonstration of antibiotic resistance by deglycosylation.
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Affiliation(s)
- Leslie Cuthbertson
- Department of Biochemistry and Biomedical Sciences, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada
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27
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Parsons JB, Rock CO. Bacterial lipids: metabolism and membrane homeostasis. Prog Lipid Res 2013; 52:249-76. [PMID: 23500459 PMCID: PMC3665635 DOI: 10.1016/j.plipres.2013.02.002] [Citation(s) in RCA: 298] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Revised: 02/27/2013] [Accepted: 02/28/2013] [Indexed: 11/29/2022]
Abstract
Membrane lipid homeostasis is a vital facet of bacterial cell physiology. For decades, research in bacterial lipid synthesis was largely confined to the Escherichia coli model system. This basic research provided a blueprint for the biochemistry of lipid metabolism that has largely defined the individual steps in bacterial fatty acid and phospholipids synthesis. The advent of genomic sequencing has revealed a surprising amount of diversity in the genes, enzymes and genetic organization of the components responsible for bacterial lipid synthesis. Although the chemical steps in fatty acid synthesis are largely conserved in bacteria, there are surprising differences in the structure and cofactor requirements for the enzymes that perform these reactions in Gram-positive and Gram-negative bacteria. This review summarizes how the explosion of new information on the diversity of biochemical and genetic regulatory mechanisms has impacted our understanding of bacterial lipid homeostasis. The potential and problems of developing therapeutics that block pathogen phospholipid synthesis are explored and evaluated. The study of bacterial lipid metabolism continues to be a rich source for new biochemistry that underlies the variety and adaptability of bacterial life styles.
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Affiliation(s)
- Joshua B Parsons
- Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
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28
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Structural basis for feed-forward transcriptional regulation of membrane lipid homeostasis in Staphylococcus aureus. PLoS Pathog 2013; 9:e1003108. [PMID: 23300457 PMCID: PMC3536700 DOI: 10.1371/journal.ppat.1003108] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Accepted: 11/15/2012] [Indexed: 11/19/2022] Open
Abstract
The biosynthesis of membrane lipids is an essential pathway for virtually all bacteria. Despite its potential importance for the development of novel antibiotics, little is known about the underlying signaling mechanisms that allow bacteria to control their membrane lipid composition within narrow limits. Recent studies disclosed an elaborate feed-forward system that senses the levels of malonyl-CoA and modulates the transcription of genes that mediate fatty acid and phospholipid synthesis in many Gram-positive bacteria including several human pathogens. A key component of this network is FapR, a transcriptional regulator that binds malonyl-CoA, but whose mode of action remains enigmatic. We report here the crystal structures of FapR from Staphylococcus aureus (SaFapR) in three relevant states of its regulation cycle. The repressor-DNA complex reveals that the operator binds two SaFapR homodimers with different affinities, involving sequence-specific contacts from the helix-turn-helix motifs to the major and minor grooves of DNA. In contrast with the elongated conformation observed for the DNA-bound FapR homodimer, binding of malonyl-CoA stabilizes a different, more compact, quaternary arrangement of the repressor, in which the two DNA-binding domains are attached to either side of the central thioesterase-like domain, resulting in a non-productive overall conformation that precludes DNA binding. The structural transition between the DNA-bound and malonyl-CoA-bound states of SaFapR involves substantial changes and large (>30 Å) inter-domain movements; however, both conformational states can be populated by the ligand-free repressor species, as confirmed by the structure of SaFapR in two distinct crystal forms. Disruption of the ability of SaFapR to monitor malonyl-CoA compromises cell growth, revealing the essentiality of membrane lipid homeostasis for S. aureus survival and uncovering novel opportunities for the development of antibiotics against this major human pathogen.
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Genome context as a predictive tool for identifying regulatory targets of the TetR family transcriptional regulators. PLoS One 2012; 7:e50562. [PMID: 23226315 PMCID: PMC3511530 DOI: 10.1371/journal.pone.0050562] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Accepted: 10/23/2012] [Indexed: 01/21/2023] Open
Abstract
TetR family transcriptional regulators (TFRs) are found in most bacteria and archea. Most of the family members that have been investigated to date are repressors of their target genes, and the majority of these, like the well-characterized protein TetR, regulate genes that encode transmembrane efflux pumps. In many cases repression by TFR proteins is reversed through the direct binding of a small-molecule ligand. The number of TFRs in the public database has grown rapidly as a result of genome sequencing and there are now thousands of family members; however virtually nothing is known about the biology and biochemistry they regulate. Generally applicable methods for predicting their regulatory targets would assist efforts to characterize the family. Here, we investigate chromosomal context of 372 TFRs from three Streptomyces species. We find that the majority (250 TFRs) are transcribed divergently from one neighboring gene, as is the case for TetR and its target tetA. We explore predicted target gene product identity and intergenic separation to see which either correlates with a direct regulatory relationship. While intergenic separation is a critical factor in regulatory prediction the identity of the putative target gene product is not. Our data suggest that those TFRs that are <200 bp from their divergently oriented neighbors are most likely to regulate them. These target genes include membrane proteins (26% of which 22% are probable membrane-associated pumps), enzymes (60%), other proteins such as transcriptional regulators (1%), and proteins having no predictive sequence motifs (13%). In addition to establishing a solid foundation for identifying targets for TFRs of unknown function, our analysis demonstrates a much greater diversity of TFR-regulated biochemical functions.
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Phosphatidic acid synthesis in bacteria. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:495-502. [PMID: 22981714 DOI: 10.1016/j.bbalip.2012.08.018] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/21/2012] [Accepted: 08/23/2012] [Indexed: 12/15/2022]
Abstract
Membrane phospholipid synthesis is a vital facet of bacterial physiology. Although the spectrum of phospholipid headgroup structures produced by bacteria is large, the key precursor to all of these molecules is phosphatidic acid (PtdOH). Glycerol-3-phosphate derived from the glycolysis via glycerol-phosphate synthase is the universal source for the glycerol backbone of PtdOH. There are two distinct families of enzymes responsible for the acylation of the 1-position of glycerol-3-phosphate. The PlsB acyltransferase was discovered in Escherichia coli, and homologs are present in many eukaryotes. This protein family primarily uses acyl-acyl carrier protein (ACP) endproducts of fatty acid synthesis as acyl donors, but may also use acyl-CoA derived from exogenous fatty acids. The second protein family, PlsY, is more widely distributed in bacteria and utilizes the unique acyl donor, acyl-phosphate, which is produced from acyl-ACP by the enzyme PlsX. The acylation of the 2-position is carried out by members of the PlsC protein family. All PlsCs use acyl-ACP as the acyl donor, although the PlsCs of the γ-proteobacteria also may use acyl-CoA. Phospholipid headgroups are precursors in the biosynthesis of other membrane-associated molecules and the diacylglycerol product of these reactions is converted to PtdOH by one of two distinct families of lipid kinases. The central importance of the de novo and recycling pathways to PtdOH in cell physiology suggest that these enzymes are suitable targets for the development of antibacterial therapeutics in Gram-positive pathogens. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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31
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Feng Y, Cronan JE. Complex binding of the FabR repressor of bacterial unsaturated fatty acid biosynthesis to its cognate promoters. Mol Microbiol 2011; 80:195-218. [PMID: 21276098 DOI: 10.1111/j.1365-2958.2011.07564.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Two transcriptional regulators, the FadR activator and the FabR repressor, control biosynthesis of unsaturated fatty acids in Escherichia coli. FabR represses expression of the two genes, fabA and fabB, required for unsaturated fatty acid synthesis and has been reported to require the presence of an unsaturated thioester (of either acyl carrier protein or CoA) in order to bind the fabA and fabB promoters in vitro. We report in vivo experiments in which unsaturated fatty acid synthesis was blocked in the absence of exogenous unsaturated fatty acids in a ΔfadR strain and found that the rates of transcription of fabA and fabB were unaffected by the lack of unsaturated thioesters. To examine the discrepancy between our in vivo results and the prior in vitro results we obtained active, natively folded forms of the E. coli and Vibrio cholerae FabRs by use of an in vitro transcription-translation system. We report that FabR bound the intact promoter regions of both fabA and fabB in the absence of unsaturated acyl thioesters, but bound the two promoters differently. Native FabR bound the fabA promoter region provided that the canonical FabR binding site is extended by inclusion of flanking sequences that overlap the neighbouring FadR binding site. In contrast, although binding to the fabB operator also required a flanking sequence, a non-specific sequence could suffice. However, unsaturated thioesters did allow FabR binding to the minimal FabR operator sites of both promoters which otherwise were not bound. Thus unsaturated thioester ligands were not essential for FabR/target DNA interaction, but acted to enhance binding. The gel mobility shift data plus in vivo expression data indicate that despite the remarkably similar arrangements of promoter elements, FadR predominately regulates fabA expression whereas FabR is the dominant regulator of fabB expression. We also report that E. coli fabR expression is not autoregulated. Complementation, qRT-PCR and fatty acid composition analyses demonstrated that V. cholerae FabR was a functional repressor of unsaturated fatty acid synthesis. However, in contrast to E. coli, gel mobility shift assays indicated that neither E. coli nor V. cholerae FabRs bound the V. cholerae fabB promoter, although both proteins efficiently bound the V. cholerae fabA promoter. This asymmetry was shown to be due to the lack of a FabR binding site within the V. cholerae fabB promoter region.
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Affiliation(s)
- Youjun Feng
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA
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32
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Pseudomonas aeruginosa aerobic fatty acid desaturase DesB is important for virulence factor production. Arch Microbiol 2010; 193:227-34. [PMID: 21184216 DOI: 10.1007/s00203-010-0665-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 11/18/2010] [Accepted: 11/30/2010] [Indexed: 01/29/2023]
Abstract
Unsaturated fatty acids (UFAs) play a pivotal role in maintaining a functional cellular membrane in response to changes in environmental factors. Unlike in other gram-negative bacteria, in Pseudomonas aeruginosa, UFA synthesis is governed by 2 pathways: (1) the anaerobic FabAB-mediated pathway and (2) the aerobic inducible DesA/DesB desaturase pathway. Although fatty acids are functional constituents of several known virulence factors, the roles of Pseudomonas aeruginosa fatty acid synthesis enzymes in virulence factor production and pathogenesis have not yet been examined. Previous studies have shown that the mycobacterial DesA1 and DesA3 proteins are required for full virulence. Therefore, we assessed the effect, if any, of mutations affecting the various UFA synthesis enzymes on virulence factor production. Testing of individual mutations or combinations of mutations revealed that desB mutants were severely deficient in the production of proteolytic enzymes, pyocyanin, and rhamnolipid. In addition, the desB mutants showed impaired swarming and twitching motilities and reduced virulence in the Caenorhabditis elegans infection model. Taken together, these results demonstrate that DesB is not only a fatty acid desaturase but also a factor required for full virulence in Pseudomonas aeruginosa. DesB may thus constitute a novel drug target.
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33
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Benamara H, Rihouey C, Jouenne T, Alexandre S. Impact of the biofilm mode of growth on the inner membrane phospholipid composition and lipid domains in Pseudomonas aeruginosa. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:98-105. [PMID: 20849811 DOI: 10.1016/j.bbamem.2010.09.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2010] [Revised: 09/02/2010] [Accepted: 09/03/2010] [Indexed: 11/30/2022]
Abstract
Many studies using genetic and proteomic approaches have revealed phenotypic differences between planktonic and sessile bacteria but the mechanisms of biofilm formation and the switch between the two growth modes are not well understood yet. In this study, we focused on inner membrane lipidome modifications when Pseudomonas aeruginosa cells were grown as biofilm. Lipid analyses were performed by Electrospray Ionization Mass Spectrometry. Results showed a drastic decrease of the uneven-numbered chain phospholipids and a slight increase of long chain PEs in sessile organisms as compared with planktonic counterparts, suggesting a better lipid stability in the bilayer and a decrease in membrane fluidity. The impact of sessile growth on lipid domains was then investigated by Brewster Angle Microscopy (BAM) and Atomic Force Microscopy (AFM). Observations showed that inner membrane lipids of P. aeruginosa formed domains when the pressure was close to physiological conditions and that these domains were larger for lipids extracted from biofilm bacteria. This is coherent with the mass spectrometry analyses.
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Affiliation(s)
- Hayette Benamara
- PBS laboratory, UMR 6270, FR 3038, CNRS, Proteomic Platform of the IFRMP23, University of Rouen, 76821 Mont-Saint-Aignan cedex, France
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34
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35
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Miller DJ, Zhang YM, Subramanian C, Rock CO, White SW. Structural basis for the transcriptional regulation of membrane lipid homeostasis. Nat Struct Mol Biol 2010; 17:971-5. [PMID: 20639888 PMCID: PMC2935088 DOI: 10.1038/nsmb.1847] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Accepted: 05/07/2010] [Indexed: 11/21/2022]
Abstract
DesT is a transcriptional repressor that regulates the genes which control the unsaturated:saturated fatty acid ratio available for membrane lipid synthesis. DesT bound to unsaturated acyl-CoA has a high affinity for its cognate palindromic DNA-binding site, whereas DesT bound to saturated acyl-CoA does not bind to this site. Structural analyses of the DesT–oleoyl-CoA–DNA and DesT–palmitoyl-CoA complexes reveal that acyl chain shape directly influences the packing of hydrophobic core residues within the DesT ligand-binding domain. These changes are propagated to the paired DNA-binding domains via conformational changes to modulate DNA binding. These structural interpretations are supported by the in vitro and in vivo characterization of site-directed mutants. The regulation of DesT by the unsaturated:saturated ratio of acyl chains rather than the concentration of a single ligand is a paradigm for understanding transcriptional regulation of membrane lipid homeostasis.
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Affiliation(s)
- Darcie J Miller
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA
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36
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Watanabe T, Tsuda S, Nishimura H, Honda Y, Watanabe T. Characterization of a Delta12-fatty acid desaturase gene from Ceriporiopsis subvermispora, a selective lignin-degrading fungus. Appl Microbiol Biotechnol 2010; 87:215-24. [PMID: 20155356 DOI: 10.1007/s00253-010-2438-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Revised: 12/29/2009] [Accepted: 01/04/2010] [Indexed: 01/26/2023]
Abstract
Ceriporiopsis subvermispora, a white-rot fungus, is characterized as one of the best biopulping fungi because it can degrade lignin selectively without serious damage to cellulose. We previously demonstrated that during the early stage of wood decay, this fungus produces large amounts of linoleic acid (18:2n-6) and degrades lignin by manganese peroxidase-catalyzed lipid peroxidation. In this study, we cloned a Delta12-fatty acid desaturase gene absolutely essential for the biosynthesis of linoleic acid as the main substrate for lipid peroxidation. This gene designated Cs-fad2 encodes a protein with three histidine-rich domains and four membrane-spanning domains characteristic of other Delta12-fatty acid desaturases. Moreover, we heterologously expressed Cs-fad2 in Saccharomyces cerevisiae lacking Delta12-fatty acid desaturase, and detected the de novo biosynthesis of linoleic acid by gas chromatography-mass spectrometry analysis. We also investigated transcription of Cs-fad2 under various conditions. The transcription was activated and repressed in the presence of a lignin fragment and exogenous fatty acids, respectively. These results may shed light on the molecular relationship between fatty acid metabolism and selective lignin degradation in C. subvermispora.
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Affiliation(s)
- Takahito Watanabe
- Laboratory of Biomass Conversion, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan
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37
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Subramanian C, Rock CO, Zhang YM. DesT coordinates the expression of anaerobic and aerobic pathways for unsaturated fatty acid biosynthesis in Pseudomonas aeruginosa. J Bacteriol 2010; 192:280-5. [PMID: 19880602 PMCID: PMC2798278 DOI: 10.1128/jb.00404-09] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 09/24/2009] [Indexed: 11/20/2022] Open
Abstract
The fabA and fabB genes are responsible for anaerobic unsaturated fatty acid formation in Pseudomonas aeruginosa. Expression of the fabAB operon was repressed by exogenous unsaturated fatty acids, and DNA sequences upstream of the translational start site were used to affinity purify DesT. The single protein interaction with the fabAB promoter detected in wild-type cell extracts was absent in the desT deletion strain, as was the repression of fabAB expression by unsaturated fatty acids. Thus, DesT senses the overall composition of the acyl-coenzyme A pool to coordinate the expression of the operons for the anaerobic (fabAB) and aerobic (desCB) pathways for unsaturated fatty acid synthesis.
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Affiliation(s)
- Chitra Subramanian
- Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105-3678
| | - Charles O. Rock
- Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105-3678
| | - Yong-Mei Zhang
- Department of Infectious Diseases, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, Tennessee 38105-3678
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38
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Zhu K, Zhang YM, Rock CO. Transcriptional regulation of membrane lipid homeostasis in Escherichia coli. J Biol Chem 2009; 284:34880-8. [PMID: 19854834 DOI: 10.1074/jbc.m109.068239] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The biophysical properties of membrane phospholipids are controlled by the composition of their constituent fatty acids and are tightly regulated in Escherichia coli. The FabR (fatty acid biosynthesis repressor) transcriptional repressor controls the proportion of unsaturated fatty acids in the membrane by regulating the expression of the fabB (beta-ketoacyl-ACP synthase I) and fabA (beta-hydroxydecanoyl-ACP dehydratase/isomerase) genes. FabR binding to a DNA palindrome located within the promoters of the fabB and fabA genes required the presence of an unsaturated acyl-acyl carrier protein (ACP) or acyl-CoA and was antagonized by saturated acyl-ACP or acyl-CoA. The FabR-dependent repression of fabB and fabA by exogenous unsaturated fatty acids confirmed the role for FabR in responding to the acyl-CoA pool composition, and the perturbation of the unsaturated:saturated acyl-ACP ratio using a specific inhibitor of lipid A formation verified FabR-dependent regulation of fabB by the acyl-ACP composition in vivo. Thus, FabR plays a key role in controlling the membrane biophysical properties by regulating gene expression in response to the composition of the long-chain acyl-thioester pool. This mechanism ensures that a balanced composition of fatty acids is available for incorporation into the membrane via the PlsB/PlsC acyltransferases.
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Affiliation(s)
- Kun Zhu
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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39
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Feng Y, Cronan JE. A new member of the Escherichia coli fad regulon: transcriptional regulation of fadM (ybaW). J Bacteriol 2009; 191:6320-8. [PMID: 19684132 PMCID: PMC2753046 DOI: 10.1128/jb.00835-09] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2009] [Accepted: 08/09/2009] [Indexed: 11/20/2022] Open
Abstract
Recently, Nie and coworkers (L. Nie, Y. Ren, A. Janakiraman, S. Smith, and H. Schulz, Biochemistry 47:9618-9626, 2008) reported a new Escherichia coli thioesterase encoded by the ybaW gene that cleaves the thioester bonds of inhibitory acyl-coenzyme A (CoA) by-products generated during beta-oxidation of certain unsaturated fatty acids. These authors suggested that ybaW expression might be regulated by FadR, the repressor of the fad (fatty acid degradation) regulon. We report mapping of the ybaW promoter and show that ybaW transcription responded to FadR in vivo. Moreover, purified FadR bound to a DNA sequence similar to the canonical FadR binding site located upstream of the ybaW coding sequence and was released from the promoter upon the addition of long-chain acyl-CoA thioesters. We therefore propose the designation fadM in place of ybaW. Although FadR regulation of fadM expression had the pattern typical of fad regulon genes, its modulation by the cyclic AMP (cAMP) receptor protein-cAMP complex (CRP-cAMP) global regulator was the opposite of that normally observed. CRP-cAMP generally acts as an activator of fad gene expression, consistent with the low status of fatty acids as carbon sources. However, glucose growth stimulated fadM expression relative to acetate growth, as did inactivation of CRP-cAMP, indicating that the complex acts as a negative regulator of this gene. The stimulation of fadM expression seen upon deletion of the gene encoding adenylate cyclase (Deltacya) was reversed by supplementation of the growth medium with cAMP. Nie and coworkers also reported that growth on a conjugated linoleic acid isomer yields much higher levels of FadM thioesterase activity than does growth on oleic acid. In contrast, we found that the conjugated linoleic acid isomer was only a weak inducer of fadM expression. Although the gene is not essential for growth, the high basal level of fadM expression under diverse growth conditions suggests that the encoded thioesterase has functions in addition to beta-oxidation.
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Affiliation(s)
- Youjun Feng
- Department of Microbiology, University of Illinois, B103 Chemical and Life Sciences Laboratory, 601 S. Goodwin Ave., Urbana, IL 61801, USA
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40
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Jerga A, Rock CO. Acyl-Acyl carrier protein regulates transcription of fatty acid biosynthetic genes via the FabT repressor in Streptococcus pneumoniae. J Biol Chem 2009; 284:15364-8. [PMID: 19376778 PMCID: PMC2708833 DOI: 10.1074/jbc.c109.002410] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Long-chain acyl-acyl carrier proteins (acyl-ACP) are established biochemical regulators of bacterial type II fatty acid synthases due to their ability to feedback-inhibit the early steps in the biosynthetic pathway. In Streptococcus pneumoniae, the expression of the fatty acid synthase (fab) genes is controlled by a helix-turn-helix transcriptional repressor called FabT. A screen of pathway intermediates identified acyl-ACP as a ligand that increased the affinity of FabT for DNA. FabT bound to a wide range of acyl-ACP chain lengths in the absence of DNA, but only the long-chain acyl-ACPs increase the affinity of FabT for DNA. FabT affinity for DNA increased with increasing acyl-ACP chain length with cis-vaccenoyl-ACP being the most effective ligand. Thus, FabT is a new ACP-interacting partner that acts as a transcriptional rheostat to fine tune the expression of the fab genes based on the demand for fatty acids.
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Affiliation(s)
- Agoston Jerga
- From the Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
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41
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Zhang YM, Rock CO. Transcriptional regulation in bacterial membrane lipid synthesis. J Lipid Res 2008; 50 Suppl:S115-9. [PMID: 18941141 DOI: 10.1194/jlr.r800046-jlr200] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This review covers the main transcriptional mechanisms that control membrane phospholipid synthesis in bacteria. The fatty acid components are the most energetically expensive modules to produce; thus, the regulation of fatty acid production is very tightly controlled to match the growth rate of cells. Gram-negative and Gram-positive bacteria have evolved different structural classes of regulators to control the genes required for fatty acid biosynthesis. Also, there are other transcriptional regulators that allow the cells to alter the structure of fatty acids in existing phospholipid molecules or to modify the structures of exogenous fatty acids prior to their incorporation into the bilayer. A major thrust for future research in this area is the identification of the ligands or effectors that control the DNA binding activity of the transcriptional regulators of fatty acid biosynthesis. With the exception of malonyl-CoA regulation of FapR from Bacillus subtilis and long-chain acyl-CoA regulation of FadR from Escherichia coli and DesT from Pseudomonas aeruginosa, the identity of these intracellular regulators remains unknown.
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Affiliation(s)
- Yong-Mei Zhang
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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42
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Zhang YM, Rock CO. Thematic review series: Glycerolipids. Acyltransferases in bacterial glycerophospholipid synthesis. J Lipid Res 2008; 49:1867-74. [PMID: 18369234 DOI: 10.1194/jlr.r800005-jlr200] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Phospholipid biosynthesis is a vital facet of bacterial physiology that begins with the synthesis of the fatty acids by a soluble type II fatty acid synthase. The bacterial glycerol-phosphate acyltransferases utilize the completed fatty acid chains to form the first membrane phospholipid and thus play a critical role in the regulation of membrane biogenesis. The first bacterial acyltransferase described was PlsB, a glycerol-phosphate acyltransferase. PlsB is a key regulatory point that coordinates membrane phospholipid formation with cell growth and macromolecular synthesis. Phosphatidic acid is then produced by PlsC, a 1-acylglycerol-phosphate acyltransferase. These two acyltransferases use thioesters of either CoA or acyl carrier protein (ACP) as the acyl donors and have homologs that perform the same reactions in higher organisms. However, the most prevalent glycerol-phosphate acyltransferase in the bacterial world is PlsY, which uses a recently discovered acyl-phosphate fatty acid intermediate as an acyl donor. This unique activated fatty acid is formed from the acyl-ACP end products of the fatty acid biosynthetic pathway by PlsX, an acyl-ACP:phosphate transacylase.
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Affiliation(s)
- Yong-Mei Zhang
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
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43
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Schujman GE, de Mendoza D. Regulation of type II fatty acid synthase in Gram-positive bacteria. Curr Opin Microbiol 2008; 11:148-52. [PMID: 18372209 DOI: 10.1016/j.mib.2008.02.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2008] [Revised: 02/05/2008] [Accepted: 02/08/2008] [Indexed: 10/22/2022]
Abstract
Bacterial cells stringently regulate the synthesis of their membrane phospholipids but the responsible mechanisms are incompletely understood. Recent biochemical, genetic and structural analyses have greatly expanded the knowledge of lipid metabolism in Gram-positive bacteria, revealing that these organisms use novel mechanisms to regulate this essential pathway. A remarkable progress was the identification of a new pathway for the initiation of phospholipid biosynthesis that uncovered a mechanism that coordinates fatty acid and phospholipid biosynthesis. Recent advances in structure determination of a global transcription factor have led to significant insights of the underlying complexities and functional elegance of membrane lipid homeostasis in Gram-positive bacteria.
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Affiliation(s)
- Gustavo E Schujman
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET) and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, 2000 Rosario, Argentina.
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Mansilla MC, Banchio CE, de Mendoza D. Signalling pathways controlling fatty acid desaturation. Subcell Biochem 2008; 49:71-99. [PMID: 18751908 DOI: 10.1007/978-1-4020-8831-5_3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Microorganisms, plants and animals regulate the synthesis of unsaturated fatty acids (UFAs) during changing environmental conditions as well as in response to nutrients. Unsaturation of fatty acid chains has important structural roles in cell membranes: a proper ratio of saturated to UFAs contributes to membrane fluidity. Alterations in this ratio have been implicated in various disease states including cardiovascular diseases, immune disorders, cancer and obesity. They are also the major components of triglycerides and intermediates in the synthesis of biologically active molecules such as eicosanoids, which mediates fever, inflammation and neurotransmission. UFAs homeostasis in many organisms is achieved by feedback regulation of fatty acid desaturases gene transcription. Here, we review recently discovered components and mechanisms of the regulatory machinery governing the transcription of fatty acid desaturases in bacteria, yeast and animals.
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Affiliation(s)
- María Cecilia Mansilla
- Departamento de Microbiologia, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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