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Radka CD. Interfacial Enzymes Enable Gram-Positive Microbes to Eat Fatty Acids. MEMBRANES 2023; 13:423. [PMID: 37103850 PMCID: PMC10146087 DOI: 10.3390/membranes13040423] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/08/2023] [Accepted: 04/09/2023] [Indexed: 06/19/2023]
Abstract
Exogenous fatty acid (eFA) activation and utilization play key roles in bacterial physiology and confer growth advantages by bypassing the need to make fatty acids for lipid synthesis. In Gram-positive bacteria, eFA activation and utilization is generally carried out by the fatty acid kinase (FakAB) two-component system that converts eFA to acyl phosphate, and the acyl-ACP:phosphate transacylase (PlsX) that catalyzes the reversible conversion of acyl phosphate to acyl-acyl carrier protein. Acyl-acyl carrier protein is a soluble format of the fatty acid that is compatible with cellular metabolic enzymes and can feed multiple processes including the fatty acid biosynthesis pathway. The combination of FakAB and PlsX enables the bacteria to channel eFA nutrients. These key enzymes are peripheral membrane interfacial proteins that associate with the membrane through amphipathic helices and hydrophobic loops. In this review, we discuss the biochemical and biophysical advances that have established the structural features that drive FakB or PlsX association with the membrane, and how these protein-lipid interactions contribute to enzyme catalysis.
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Affiliation(s)
- Christopher D Radka
- Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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2
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Jiang Y, Qin M, Guo Z. Substrate Recognition and Catalytic Mechanism of the Phosphate Acyltransferase PlsX from Bacillus subtilis. Chembiochem 2020; 21:2019-2028. [PMID: 32180316 DOI: 10.1002/cbic.202000015] [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: 01/11/2020] [Revised: 02/28/2020] [Indexed: 12/18/2022]
Abstract
Phosphate: acyl-acyl carrier protein (ACP) acyltransferase PlsX is a peripheral enzyme catalysing acyl transfer to orthophosphate in phospholipid synthesis. Little is known about how it recognises substrates and catalyses the acyl transfer. Here we show that its active site includes many residues lining a long, narrow gorge at the dimeric interface, two positive residues forming a positive ACP docking pad next to the interfacial gorge, and a number of strictly conserved residues significantly contributing to the catalytic activity. These findings suggest a substrate recognition mode and a catalytic mechanism that are different from those of phosphotransacetylases catalysing a similar acyl transfer reaction. The catalytic mechanism involves substrate activation and transition-state stabilization by two strictly conserved residues, Lys184 and Asn229. Another noticeable feature of the catalysis is the release of the acyl phosphate product near the membrane, which might facilitate its membrane insertion.
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Affiliation(s)
- Yiping Jiang
- Shenzhen Research Institute Hong Kong Branch of Guangdong Southern Marine Science and Engineering Laboratory (Guangzhou) and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Mingming Qin
- Shenzhen Research Institute Hong Kong Branch of Guangdong Southern Marine Science and Engineering Laboratory (Guangzhou) and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Zhihong Guo
- Shenzhen Research Institute Hong Kong Branch of Guangdong Southern Marine Science and Engineering Laboratory (Guangzhou) and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
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3
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Sastre DE, Pulschen AA, Basso LGM, Benites Pariente JS, Marques Netto CGC, Machinandiarena F, Albanesi D, Navarro MVAS, de Mendoza D, Gueiros-Filho FJ. The phosphatidic acid pathway enzyme PlsX plays both catalytic and channeling roles in bacterial phospholipid synthesis. J Biol Chem 2020; 295:2148-2159. [PMID: 31919098 DOI: 10.1074/jbc.ra119.011147] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 12/19/2019] [Indexed: 12/29/2022] Open
Abstract
PlsX is the first enzyme in the pathway that produces phosphatidic acid in Gram-positive bacteria. It makes acylphosphate from acyl-acyl carrier protein (acyl-ACP) and is also involved in coordinating phospholipid and fatty acid biosyntheses. PlsX is a peripheral membrane enzyme in Bacillus subtilis, but how it associates with the membrane remains largely unknown. In the present study, using fluorescence microscopy, liposome sedimentation, differential scanning calorimetry, and acyltransferase assays, we determined that PlsX binds directly to lipid bilayers and identified its membrane anchoring moiety, consisting of a hydrophobic loop located at the tip of two amphipathic dimerization helices. To establish the role of the membrane association of PlsX in acylphosphate synthesis and in the flux through the phosphatidic acid pathway, we then created mutations and gene fusions that prevent PlsX's interaction with the membrane. Interestingly, phospholipid synthesis was severely hampered in cells in which PlsX was detached from the membrane, and results from metabolic labeling indicated that these cells accumulated free fatty acids. Because the same mutations did not affect PlsX transacylase activity, we conclude that membrane association is required for the proper delivery of PlsX's product to PlsY, the next enzyme in the phosphatidic acid pathway. We conclude that PlsX plays a dual role in phospholipid synthesis, acting both as a catalyst and as a chaperone protein that mediates substrate channeling into the pathway.
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Affiliation(s)
- Diego E Sastre
- Instituto de Química, Departamento de Bioquímica, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil; Grupo de Biofísica Molecular "Sergio Mascarenhas," Instituto de Física de São Carlos, Departamento de Biofísica Molecular, Universidade de São Paulo, São Carlos, SP 13560-970, Brazil
| | - André A Pulschen
- Instituto de Química, Departamento de Bioquímica, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil
| | - Luis G M Basso
- Departamento de Física, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP 14040-901, Brazil
| | | | | | - Federico Machinandiarena
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe S2002LRK, Argentina
| | - Daniela Albanesi
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe S2002LRK, Argentina
| | - Marcos V A S Navarro
- Grupo de Biofísica Molecular "Sergio Mascarenhas," Instituto de Física de São Carlos, Departamento de Biofísica Molecular, Universidade de São Paulo, São Carlos, SP 13560-970, Brazil
| | - Diego de Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR), CONICET and Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Santa Fe S2002LRK, Argentina.
| | - Frederico J Gueiros-Filho
- Instituto de Química, Departamento de Bioquímica, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil.
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4
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Sastre DE, Basso LGM, Trastoy B, Cifuente JO, Contreras X, Gueiros-Filho F, de Mendoza D, Navarro MVAS, Guerin ME. Membrane fluidity adjusts the insertion of the transacylase PlsX to regulate phospholipid biosynthesis in Gram-positive bacteria. J Biol Chem 2019; 295:2136-2147. [PMID: 31796629 DOI: 10.1074/jbc.ra119.011122] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/19/2019] [Indexed: 12/24/2022] Open
Abstract
PlsX plays a central role in the coordination of fatty acid and phospholipid biosynthesis in Gram-positive bacteria. PlsX is a peripheral membrane acyltransferase that catalyzes the conversion of acyl-ACP to acyl-phosphate, which is in turn utilized by the polytopic membrane acyltransferase PlsY on the pathway of bacterial phospholipid biosynthesis. We have recently studied the interaction between PlsX and membrane phospholipids in vivo and in vitro, and observed that membrane association is necessary for the efficient transfer of acyl-phosphate to PlsY. However, understanding the molecular basis of such a channeling mechanism remains a major challenge. Here, we disentangle the binding and insertion events of the enzyme to the membrane, and the subsequent catalysis. We show that PlsX membrane binding is a process mostly mediated by phospholipid charge, whereas fatty acid saturation and membrane fluidity remarkably influence the membrane insertion step. Strikingly, the PlsXL254E mutant, whose biological functionality was severely compromised in vivo but remains catalytically active in vitro, was able to superficially bind to phospholipid vesicles, nevertheless, it loses the insertion capacity, strongly supporting the importance of membrane insertion in acyl-phosphate delivery. We propose a mechanism in which membrane fluidity governs the insertion of PlsX and thus regulates the biosynthesis of phospholipids in Gram-positive bacteria. This model may be operational in other peripheral membrane proteins with an unprecedented impact in drug discovery/development strategies.
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Affiliation(s)
- Diego E Sastre
- Grupo de Biofísica Molecular "Sergio Mascarenhas," Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brasil.
| | - Luis G M Basso
- Departamento de Física, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brasil
| | - Beatriz Trastoy
- Structural Biology Unit, CIC bioGUNE Technological Park of Bizkaia, Derio, Vizcaya, Spain
| | - Javier O Cifuente
- Structural Biology Unit, CIC bioGUNE Technological Park of Bizkaia, Derio, Vizcaya, Spain
| | - Xabier Contreras
- IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain; Instituto Biofisika, Consejo Superior de Investigaciones Científicas, Universidad del País Vasco/Euskal Herriko Unibertsitatea (CSIC,UPV/EHU), Barrio Sarriena s/n, Leioa, 48940 Bizkaia, Spain; Departamento de Bioquímica, Universidad del País Vasco, Leioa, 48940 Bizkaia, Spain
| | - Frederico Gueiros-Filho
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo, Brasil
| | - Diego de Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR), Rosario, Santa Fe, Argentina
| | - Marcos V A S Navarro
- Grupo de Biofísica Molecular "Sergio Mascarenhas," Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brasil
| | - Marcelo E Guerin
- Structural Biology Unit, CIC bioGUNE Technological Park of Bizkaia, Derio, Vizcaya, Spain; IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain.
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5
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Jiang Y, Dai X, Qin M, Guo Z. Identification of an amphipathic peptide sensor of the Bacillus subtilis fluid membrane microdomains. Commun Biol 2019; 2:316. [PMID: 31453380 PMCID: PMC6702220 DOI: 10.1038/s42003-019-0562-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 07/29/2019] [Indexed: 01/26/2023] Open
Abstract
Regions of increased fluidity are newly found bacterial membrane microdomains that are composed of short, unsaturated and branched fatty acyl chains in a fluid and disordered state. Currently, little is known about how proteins are recruited and localized to these membrane domains. Here, we identify a short amphipathic α-peptide in a previously unreported crystal structure and show that it is responsible for peripheral localization of the phosphate acyltransferase PlsX to the fluid microdomains in Bacillus subtilis. Mutations disrupting the amphipathic interaction or increasing the nonpolar interaction are found to redistribute the protein to the cytosol or other part of the plasma membrane, causing growth defects. These results reveal a mechanism of peripheral membrane sensing through optimizing nonpolar interaction with the special lipids in the microdomains. This finding shows that the fluid membrane microdomains may take advantage of their unique lipid environment as a means of recruiting and organizing proteins.
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Affiliation(s)
- Yiping Jiang
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
| | - Xin Dai
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
| | - Mingming Qin
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
| | - Zhihong Guo
- Shenzhen Research Institute and Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR China
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6
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Pang D, Liao S, Wang W, Mu L, Li E, Shen W, Liu F, Zou Y. Destruction of the cell membrane and inhibition of cell phosphatidic acid biosynthesis inStaphylococcus aureus: an explanation for the antibacterial mechanism of morusin. Food Funct 2019; 10:6438-6446. [DOI: 10.1039/c9fo01233h] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Morusin from mulberry inhibits the growth ofS. aureusby destroying its cell membrane and further moderating the phosphatidic acid biosynthesis pathway.
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Affiliation(s)
- Daorui Pang
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
| | - Sentai Liao
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
| | - Weifei Wang
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
| | - Lixia Mu
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
| | - Erna Li
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
| | - Weizhi Shen
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
| | - Fan Liu
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
| | - Yuxiao Zou
- Sericultural & Agri-Food Research Institute
- Guangdong Academy of Agricultural Sciences; Guangdong Key Laboratory of Agricultural Products Processing; Key Laboratory of Functional Foods
- Ministry of Agriculture and Rural Affairs
- Guangzhou 510610
- China
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7
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Kóbori TO, Uzumaki T, Kis M, Kovács L, Domonkos I, Itoh S, Krynická V, Kuppusamy SG, Zakar T, Dean J, Szilák L, Komenda J, Gombos Z, Ughy B. Phosphatidylglycerol is implicated in divisome formation and metabolic processes of cyanobacteria. JOURNAL OF PLANT PHYSIOLOGY 2018; 223:96-104. [PMID: 29558689 DOI: 10.1016/j.jplph.2018.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 02/26/2018] [Accepted: 02/27/2018] [Indexed: 06/08/2023]
Abstract
Phosphatidylglycerol is an essential phospholipid for photosynthesis and other cellular processes. We investigated the role of phosphatidylglycerol in cell division and metabolism in a phophatidylglycerol-auxotrophic strain of Synechococcus PCC7942. Here we show that phosphatidylglycerol is essential for the photosynthetic electron transfer and for the oligomerisation of the photosynthetic complexes, notably, we revealed that this lipid is important for non-linear electron transport. Furthermore, we demonstrate that phosphatidylglycerol starvation elevated the expressions of proteins of nitrogen and carbon metabolism. Moreover, we show that phosphatidylglycerol-deficient cells changed the morphology, became elongated, the FtsZ ring did not assemble correctly, and subsequently the division was hindered. However, supplementation with phosphatidylglycerol restored the ring-like structure at the mid-cell region and the normal cell size, demonstrating the phosphatidylglycerol is needed for normal septum formation. Taken together, central roles of phosphatidylglycerol were revealed; it is implicated in the photosynthetic activity, the metabolism and the fission of bacteria.
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Affiliation(s)
- Tímea O Kóbori
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary; Doctoral School of Biology, University of Szeged, H-6726 Szeged, Hungary
| | - Tatsuya Uzumaki
- Center for Gene Research, Nagoya University, Furocyo, Chikusa, Nagoya 464-8607, Japan
| | - Mihály Kis
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - László Kovács
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Ildikó Domonkos
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Shigeru Itoh
- Center for Gene Research, Nagoya University, Furocyo, Chikusa, Nagoya 464-8607, Japan
| | - Vendula Krynická
- Institute of Microbiology, Center Algatech, Czech Academy of Sciences, Opatovický mlýn, 37981 Třeboň, Czech Republic
| | - Saravanan G Kuppusamy
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Tomas Zakar
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Jason Dean
- Institute of Microbiology, Center Algatech, Czech Academy of Sciences, Opatovický mlýn, 37981 Třeboň, Czech Republic
| | - László Szilák
- Institute of Biology, Savaria Campus, Eötvös Lorand University, Szombathely, H-9700, Hungary
| | - Josef Komenda
- Institute of Microbiology, Center Algatech, Czech Academy of Sciences, Opatovický mlýn, 37981 Třeboň, Czech Republic
| | - Zoltán Gombos
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary
| | - Bettina Ughy
- Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences, H-6701 Szeged, Hungary.
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8
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Pulschen AA, Sastre DE, Machinandiarena F, Crotta Asis A, Albanesi D, de Mendoza D, Gueiros-Filho FJ. The stringent response plays a key role in Bacillus subtilis survival of fatty acid starvation. Mol Microbiol 2016; 103:698-712. [PMID: 27875634 DOI: 10.1111/mmi.13582] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2016] [Indexed: 11/26/2022]
Abstract
The stringent response is a universal adaptive mechanism to protect bacteria from nutritional and environmental stresses. The role of the stringent response during lipid starvation has been studied only in Gram-negative bacteria. Here, we report that the stringent response also plays a crucial role in the adaptation of the model Gram-positive Bacillus subtilis to fatty acid starvation. B. subtilis lacking all three (p)ppGpp-synthetases (RelBs , RelP and RelQ) or bearing a RelBs variant that no longer synthesizes (p)ppGpp suffer extreme loss of viability on lipid starvation. Loss of viability is paralleled by perturbation of membrane integrity and function, with collapse of membrane potential as the likely cause of death. Although no increment of (p)ppGpp could be detected in lipid starved B. subtilis, we observed a substantial increase in the GTP/ATP ratio of strains incapable of synthesizing (p)ppGpp. Artificially lowering GTP with decoyinine rescued viability of such strains, confirming observations that low intracellular GTP is important for survival of nutritional stresses. Altogether, our results show that activation of the stringent response by lipid starvation is a broadly conserved response of bacteria and that a key role of (p)ppGpp is to couple biosynthetic processes that become detrimental if uncoordinated.
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Affiliation(s)
- André A Pulschen
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Brazil
| | - Diego E Sastre
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Brazil
| | - Federico Machinandiarena
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
| | - Agostina Crotta Asis
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
| | - Daniela Albanesi
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
| | - Diego de Mendoza
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina
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9
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Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains. Proc Natl Acad Sci U S A 2016; 113:E7077-E7086. [PMID: 27791134 DOI: 10.1073/pnas.1611173113] [Citation(s) in RCA: 256] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Daptomycin is a highly efficient last-resort antibiotic that targets the bacterial cell membrane. Despite its clinical importance, the exact mechanism by which daptomycin kills bacteria is not fully understood. Different experiments have led to different models, including (i) blockage of cell wall synthesis, (ii) membrane pore formation, and (iii) the generation of altered membrane curvature leading to aberrant recruitment of proteins. To determine which model is correct, we carried out a comprehensive mode-of-action study using the model organism Bacillus subtilis and different assays, including proteomics, ionomics, and fluorescence light microscopy. We found that daptomycin causes a gradual decrease in membrane potential but does not form discrete membrane pores. Although we found no evidence for altered membrane curvature, we confirmed that daptomycin inhibits cell wall synthesis. Interestingly, using different fluorescent lipid probes, we showed that binding of daptomycin led to a drastic rearrangement of fluid lipid domains, affecting overall membrane fluidity. Importantly, these changes resulted in the rapid detachment of the membrane-associated lipid II synthase MurG and the phospholipid synthase PlsX. Both proteins preferentially colocalize with fluid membrane microdomains. Delocalization of these proteins presumably is a key reason why daptomycin blocks cell wall synthesis. Finally, clustering of fluid lipids by daptomycin likely causes hydrophobic mismatches between fluid and more rigid membrane areas. This mismatch can facilitate proton leakage and may explain the gradual membrane depolarization observed with daptomycin. Targeting of fluid lipid domains has not been described before for antibiotics and adds another dimension to our understanding of membrane-active antibiotics.
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10
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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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11
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Mitra SD, Afonina I, Kline KA. Right Place, Right Time: Focalization of Membrane Proteins in Gram-Positive Bacteria. Trends Microbiol 2016; 24:611-621. [PMID: 27117048 DOI: 10.1016/j.tim.2016.03.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 03/03/2016] [Accepted: 03/24/2016] [Indexed: 11/25/2022]
Abstract
Membrane proteins represent a significant proportion of total bacterial proteins and perform vital cellular functions ranging from exchanging metabolites and genetic material, secretion and sorting, sensing signal molecules, and cell division. Many of these functions are carried out at distinct foci on the bacterial membrane, and this subcellular localization can be coordinated by a number of factors, including lipid microdomains, protein-protein interactions, and membrane curvature. Elucidating the mechanisms behind focal protein localization in bacteria informs not only protein structure-function correlation, but also how to disrupt the protein function to limit virulence. Here we review recent advances describing a functional role for subcellular localization of membrane proteins involved in genetic transfer, secretion and sorting, cell division and growth, and signaling.
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Affiliation(s)
- Sumitra D Mitra
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
| | - Irina Afonina
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore
| | - Kimberly A Kline
- Singapore Centre for Environmental Life Sciences Engineering, School of Biological Sciences, Nanyang Technological University, Singapore.
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