1
|
Peng Y, Chen B. Role of cell membrane homeostasis in the pathogenicity of pathogenic filamentous fungi. Virulence 2024; 15:2299183. [PMID: 38156783 PMCID: PMC10761126 DOI: 10.1080/21505594.2023.2299183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2023] [Accepted: 12/20/2023] [Indexed: 01/03/2024] Open
Abstract
The cell membrane forms a fundamental part of all living cells and participates in a variety of physiological processes, such as material exchange, stress response, cell recognition, signal transduction, cellular immunity, apoptosis, and pathogenicity. Here, we review the mechanisms and functions of the membrane structure (lipid components of the membrane and the biosynthesis of unsaturated fatty acids), membrane proteins (transmembrane proteins and proteins contributing to membrane curvature), transcriptional regulation, and cell wall components that influence the virulence and pathogenicity of filamentous fungi.
Collapse
Affiliation(s)
- Yuejin Peng
- Yunnan State Key Laboratory of Conservation and Utilization of Biological Resources, Yunnan Agricultural University, Kunming, Yunnan, China
| | - Bin Chen
- Yunnan State Key Laboratory of Conservation and Utilization of Biological Resources, Yunnan Agricultural University, Kunming, Yunnan, China
| |
Collapse
|
2
|
Caravaca F, Torres P, Díaz G, Roldán A. Selective shifts in the rhizosphere microbiome during the drought season could explain the success of the invader Nicotiana glauca in semiarid ecosystems. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 946:174444. [PMID: 38964394 DOI: 10.1016/j.scitotenv.2024.174444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 06/28/2024] [Accepted: 06/30/2024] [Indexed: 07/06/2024]
Abstract
The rhizosphere microbiome plays a crucial role in the ability of plants to colonize and thrive in stressful conditions such as drought, which could be decisive for the success of exotic plant invasion in the context of global climate change. The aim of this investigation was to examine differences in the composition, structure, and functional traits of the microbial community of the invader Nicotiana glauca R.C. Graham and native species growing at seven different Mediterranean semiarid locations under two distinct levels of water availability, corresponding to the wet and dry seasons. The results show that the phylum Actinobacteriota was an indicator phylum of the dry season as well as for the community of N. glauca. The dominant indicator bacterial families of the dry season were 67-14 (unclassified family), Pseudonocardiaceae, and Sphingomonadaceae, being relatively more abundant in the invasive rhizosphere. The relative abundances of the indicator fungal families Aspergillaceae (particularly the indicator genus Aspergillus), Glomeraceae, and Claroideoglomeraceae were higher in the invasive rhizosphere. The relative abundance of mycorrhizal fungi was higher in the invasive rhizosphere in the dry season (by about 40 % in comparison to that of native plants), without significant differences between invasive and native plants in the wet season. Bacterial potential functional traits related to energy and precursor metabolites production and also biosynthesis of cell wall, cofactors, vitamins, and amino acids as well as catabolic enzymes involved in the P cycle prevailed in the invasive rhizosphere under drought conditions. This study shows that the pronounced and beneficial shifts in the microbiome assembly and functions in the rhizosphere of N. glauca under conditions of low soil water availability can represent a clear advantage for its establishment.
Collapse
Affiliation(s)
- F Caravaca
- CSIC-Centro de Edafología y Biología Aplicada del Segura, Department of Soil and Water Conservation, P.O. Box 164, Campus de Espinardo 30100, Murcia, Spain.
| | - P Torres
- Universidad Miguel Hernández de Elche, Department of Applied Biology, Avda. Ferrocarril, s/n. Edf. Laboratorios-03202-Elche, Alicante, Spain
| | - G Díaz
- Universidad Miguel Hernández de Elche, Department of Applied Biology, Avda. Ferrocarril, s/n. Edf. Laboratorios-03202-Elche, Alicante, Spain
| | - A Roldán
- CSIC-Centro de Edafología y Biología Aplicada del Segura, Department of Soil and Water Conservation, P.O. Box 164, Campus de Espinardo 30100, Murcia, Spain
| |
Collapse
|
3
|
Koo BM, Todor H, Sun J, van Gestel J, Hawkins JS, Hearne CC, Banta AB, Huang KC, Peters JM, Gross CA. Comprehensive double-mutant analysis of the Bacillus subtilis envelope using double-CRISPRi. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.14.608006. [PMID: 39185233 PMCID: PMC11343205 DOI: 10.1101/2024.08.14.608006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Understanding bacterial gene function remains a major biological challenge. Double-mutant genetic interaction (GI) analysis addresses this challenge by uncovering the functional partners of targeted genes, allowing us to associate genes of unknown function with novel pathways and unravel connections between well-studied pathways, but is difficult to implement at the genome-scale. Here, we develop and use double-CRISPRi to systematically quantify genetic interactions at scale in the Bacillus subtilis envelope, including essential genes. We discover > 1000 known and novel genetic interactions. Our analysis pipeline and experimental follow-ups reveal the distinct roles of paralogous genes such as the mreB and mbl actin homologs, and identify new genes involved in the well-studied process of cell division. Overall, our study provides valuable insights into gene function and demonstrates the utility of double-CRISPRi for high-throughput dissection of bacterial gene networks, providing a blueprint for future studies in diverse bacterial species.
Collapse
Affiliation(s)
- Byoung-Mo Koo
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Horia Todor
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Jordi van Gestel
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - John S. Hawkins
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Cameron C. Hearne
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Amy B. Banta
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
| | - Jason M. Peters
- Pharmaceutical Sciences Division, School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Carol A. Gross
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, California, USA
- California Institute of Quantitative Biology, University of California, San Francisco, San Francisco, CA, USA
- Lead Contact
| |
Collapse
|
4
|
George NL, Bennett EC, Orlando BJ. Guarding the walls: the multifaceted roles of Bce modules in cell envelope stress sensing and antimicrobial resistance. J Bacteriol 2024; 206:e0012324. [PMID: 38869304 PMCID: PMC11270860 DOI: 10.1128/jb.00123-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024] Open
Abstract
Bacteria have developed diverse strategies for defending their cell envelopes from external threats. In Firmicutes, one widespread strategy is to use Bce modules-membrane protein complexes that unite a peptide-detoxifying ABC transporter with a stress response coordinating two-component system. These modules provide specific, front-line defense for a wide variety of antimicrobial peptides and small molecule antibiotics as well as coordinate responses for heat, acid, and oxidative stress. Because of these abilities, Bce modules play important roles in virulence and the development of antibiotic resistance in a variety of pathogens, including Staphylococcus, Streptococcus, and Enterococcus species. Despite their importance, Bce modules are still poorly understood, with scattered functional data in only a small number of species. In this review, we will discuss Bce module structure in light of recent cryo-electron microscopy structures of the B. subtilis BceABRS module and explore the common threads and variations-on-a-theme in Bce module mechanisms across species. We also highlight the many remaining questions about Bce module function. Understanding these multifunctional membrane complexes will enhance our understanding of bacterial stress sensing and may point toward new therapeutic targets for highly resistant pathogens.
Collapse
Affiliation(s)
- Natasha L. George
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, Michigan, USA
| | - Ellen C. Bennett
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, Michigan, USA
| | - Benjamin J. Orlando
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| |
Collapse
|
5
|
Roney IJ, Rudner DZ. Bacillus subtilis uses the SigM signaling pathway to prioritize the use of its lipid carrier for cell wall synthesis. PLoS Biol 2024; 22:e3002589. [PMID: 38683856 PMCID: PMC11081497 DOI: 10.1371/journal.pbio.3002589] [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: 08/25/2023] [Revised: 05/09/2024] [Accepted: 03/13/2024] [Indexed: 05/02/2024] Open
Abstract
Peptidoglycan (PG) and most surface glycopolymers and their modifications are built in the cytoplasm on the lipid carrier undecaprenyl phosphate (UndP). These lipid-linked precursors are then flipped across the membrane and polymerized or directly transferred to surface polymers, lipids, or proteins. Despite its essential role in envelope biogenesis, UndP is maintained at low levels in the cytoplasmic membrane. The mechanisms by which bacteria distribute this limited resource among competing pathways is currently unknown. Here, we report that the Bacillus subtilis transcription factor SigM and its membrane-anchored anti-sigma factor respond to UndP levels and prioritize its use for the synthesis of the only essential surface polymer, the cell wall. Antibiotics that target virtually every step in PG synthesis activate SigM-directed gene expression, confounding identification of the signal and the logic of this stress-response pathway. Through systematic analyses, we discovered 2 distinct responses to these antibiotics. Drugs that trap UndP, UndP-linked intermediates, or precursors trigger SigM release from the membrane in <2 min, rapidly activating transcription. By contrasts, antibiotics that inhibited cell wall synthesis without directly affecting UndP induce SigM more slowly. We show that activation in the latter case can be explained by the accumulation of UndP-linked wall teichoic acid precursors that cannot be transferred to the PG due to the block in its synthesis. Furthermore, we report that reduction in UndP synthesis rapidly induces SigM, while increasing UndP production can dampen the SigM response. Finally, we show that SigM becomes essential for viability when the availability of UndP is restricted. Altogether, our data support a model in which the SigM pathway functions to homeostatically control UndP usage. When UndP levels are sufficiently high, the anti-sigma factor complex holds SigM inactive. When levels of UndP are reduced, SigM activates genes that increase flux through the PG synthesis pathway, boost UndP recycling, and liberate the lipid carrier from nonessential surface polymer pathways. Analogous homeostatic pathways that prioritize UndP usage are likely to be common in bacteria.
Collapse
Affiliation(s)
- Ian J. Roney
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - David Z. Rudner
- Department of Microbiology, Harvard Medical School, Boston, Massachusetts, United States of America
| |
Collapse
|
6
|
Shtaiwi A, Khan SU, Khedraoui M, Alaraj M, Samadi A, Chtita S. A comprehensive computational study to explore promising natural bioactive compounds targeting glycosyltransferase MurG in Escherichia coli for potential drug development. Sci Rep 2024; 14:7098. [PMID: 38532068 DOI: 10.1038/s41598-024-57702-x] [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: 11/24/2023] [Accepted: 03/21/2024] [Indexed: 03/28/2024] Open
Abstract
Peptidoglycan is a carbohydrate with a cross-linked structure that protects the cytoplasmic membrane of bacterial cells from damage. The mechanism of peptidoglycan biosynthesis involves the main synthesizing enzyme glycosyltransferase MurG, which is known as a potential target for antibiotic therapy. Many MurG inhibitors have been recognized as MurG targets, but high toxicity and drug-resistant Escherichia coli strains remain the most important problems for further development. In addition, the discovery of selective MurG inhibitors has been limited to the synthesis of peptidoglycan-mimicking compounds. The present study employed drug discovery, such as virtual screening using molecular docking, drug likeness ADMET proprieties predictions, and molecular dynamics (MD) simulation, to identify potential natural products (NPs) for Escherichia coli. We conducted a screening of 30,926 NPs from the NPASS database. Subsequently, 20 of these compounds successfully passed the potency, pharmacokinetic, ADMET screening assays, and their validation was further confirmed through molecular docking. The best three hits and the standard were chosen for further MD simulations up to 400 ns and energy calculations to investigate the stability of the NPs-MurG complexes. The analyses of MD simulations and total binding energies suggested the higher stability of NPC272174. The potential compounds can be further explored in vivo and in vitro for promising novel antibacterial drug discovery.
Collapse
Affiliation(s)
- Amneh Shtaiwi
- Faculty of Pharmacy, Middle East University, Queen Alia Airport Street, Amman, P.O. Box No. 11610, Jordan.
| | - Shafi Ullah Khan
- Interdisciplinary Research Unit for Cancer Prevention and Treatment, Baclesse Cancer Centre, Université de Caen Normandie Inserm Anticipe UMR 1086, Normandie Univ, Research Building, F‑14000 François 3 Avenue Général Harris, BP 45026, 14076, Cedex 05 Caen, France
- Centre François Baclesse, Avenue Général Harris, 14076, Caen Cedex, France
| | - Meriem Khedraoui
- Laboratory of Analytical and Molecular Chemistry, Faculty of Sciences Ben M'Sik, Hassan II University of Casablanca, B. P 7955, Casablanca, Morocco
| | - Mohd Alaraj
- Faculty of Pharmacy, University of Jerash, Jerash, Jordan
| | - Abdelouahid Samadi
- Department of Chemistry, College of Science, UAEU, P.O. Box No. 15551, Al Ain, UAE.
| | - Samir Chtita
- Laboratory of Analytical and Molecular Chemistry, Faculty of Sciences Ben M'Sik, Hassan II University of Casablanca, B. P 7955, Casablanca, Morocco
| |
Collapse
|
7
|
Willdigg JR, Patel Y, Arquilevich BE, Subramanian C, Frank MW, Rock CO, Helmann JD. The Bacillus subtilis cell envelope stress-inducible ytpAB operon modulates membrane properties and contributes to bacitracin resistance. J Bacteriol 2024; 206:e0001524. [PMID: 38323910 PMCID: PMC10955860 DOI: 10.1128/jb.00015-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 01/17/2024] [Indexed: 02/08/2024] Open
Abstract
Antibiotics that inhibit peptidoglycan synthesis trigger the activation of both specific and general protective responses. σM responds to diverse antibiotics that inhibit cell wall synthesis. Here, we demonstrate that cell wall-inhibiting drugs, such as bacitracin and cefuroxime, induce the σM-dependent ytpAB operon. YtpA is a predicted hydrolase previously proposed to generate the putative lysophospholipid antibiotic bacilysocin (lysophosphatidylglycerol), and YtpB is the branchpoint enzyme for the synthesis of membrane-localized C35 terpenoids. Using targeted lipidomics, we reveal that YtpA is not required for the production of lysophosphatidylglycerol. Nevertheless, ytpA was critical for growth in a mutant strain defective for homeoviscous adaptation due to a lack of genes for the synthesis of branched chain fatty acids and the Des phospholipid desaturase. Consistently, overexpression of ytpA increased membrane fluidity as monitored by fluorescence anisotropy. The ytpA gene contributes to bacitracin resistance in mutants additionally lacking the bceAB or bcrC genes, which directly mediate bacitracin resistance. These epistatic interactions support a model in which σM-dependent induction of the ytpAB operon helps cells tolerate bacitracin stress, either by facilitating the flipping of the undecaprenyl phosphate carrier lipid or by impacting the assembly or function of membrane-associated complexes involved in cell wall homeostasis.IMPORTANCEPeptidoglycan synthesis inhibitors include some of our most important antibiotics. In Bacillus subtilis, peptidoglycan synthesis inhibitors induce the σM regulon, which is critical for intrinsic antibiotic resistance. The σM-dependent ytpAB operon encodes a predicted hydrolase (YtpA) and the enzyme that initiates the synthesis of C35 terpenoids (YtpB). Our results suggest that YtpA is critical in cells defective in homeoviscous adaptation. Furthermore, we find that YtpA functions cooperatively with the BceAB and BcrC proteins in conferring intrinsic resistance to bacitracin, a peptide antibiotic that binds tightly to the undecaprenyl-pyrophosphate lipid carrier that sustains peptidoglycan synthesis.
Collapse
Affiliation(s)
| | - Yesha Patel
- Department of Microbiology, Cornell University, Ithaca, New York, USA
| | | | - Chitra Subramanian
- Department of Host Microbe Interactions, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Matthew W. Frank
- Department of Host Microbe Interactions, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Charles O. Rock
- Department of Host Microbe Interactions, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - John D. Helmann
- Department of Microbiology, Cornell University, Ithaca, New York, USA
| |
Collapse
|
8
|
Abstract
By chance, we discovered a window of extracellular magnesium (Mg2+) availability that modulates the division frequency of Bacillus subtilis without affecting its growth rate. In this window, cells grown with excess Mg2+ produce shorter cells than do those grown in unsupplemented medium. The Mg2+-responsive adjustment in cell length occurs in both rich and minimal media as well as in domesticated and undomesticated strains. Of other divalent cations tested, manganese (Mn2+) and zinc (Zn2+) also resulted in cell shortening, but this occurred only at concentrations that affected growth. Cell length decreased proportionally with increasing Mg2+ from 0.2 mM to 4.0 mM, with little or no detectable change being observed in labile, intracellular Mg2+, based on a riboswitch reporter. Cells grown in excess Mg2+ had fewer nucleoids and possessed more FtsZ-rings per unit cell length, consistent with the increased division frequency. Remarkably, when shifting cells from unsupplemented to supplemented medium, more than half of the cell length decrease occurred in the first 10 min, consistent with rapid division onset. Relative to unsupplemented cells, cells growing at steady-state with excess Mg2+ showed an enhanced expression of a large number of SigB-regulated genes and the activation of the Fur, MntR, and Zur regulons. Thus, by manipulating the availability of one nutrient, we were able to uncouple the growth rate from the division frequency and identify transcriptional changes that suggest that cell division is accompanied by the general stress response and an enhanced demand to sequester and/or increase the uptake of iron, Mn2+, and Zn2+. IMPORTANCE The signals that cells use to trigger cell division are unknown. Although division is often considered intrinsic to the cell cycle, microorganisms can continue to grow and repeat rounds of DNA replication without dividing, indicating that cycles of division can be skipped. Here, we show that by manipulating a single nutrient, namely, Mg2+, cell division can be uncoupled from the growth rate. This finding can be applied to investigate the nature of the cell division signal(s).
Collapse
|
9
|
Wilhelm L, Ducret A, Grangeasse C. New insights into the Undecaprenol monophosphate recycling pathway of Streptococcus pneumoniae. FEMS Microbiol Lett 2023; 370:fnad109. [PMID: 37849218 DOI: 10.1093/femsle/fnad109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 10/08/2023] [Accepted: 10/16/2023] [Indexed: 10/19/2023] Open
Abstract
Recycling of undecaprenol pyrophosphate is critical to regenerate the pool of undecaprenol monophosphate required for cell wall biosynthesis. Undecaprenol pyrophosphate is dephosphorylated by membrane-associated undecaprenyl pyrophosphate phosphatases such as UppP or type 2 Phosphatidic Acid Phosphatases (PAP2) and then transferred across the cytoplasmic membrane by Und-P flippases such as PopT (DUF368-containing protein) or UptA (a DedA family protein). While the deletion of uppP in S. pneumoniae has been reported to increase susceptibility to bacitracin and reduce infectivity in a murine infection model, the presence of PAP2 family proteins or Und-P flippases and their potential interplay with UppP in S. pneumoniae remained unknown. In this report, we identified two PAP2 family proteins and a DUF368-containing protein and investigated their roles together with that of UppP in cell growth, cell morphology and susceptibility to bacitracin in S. pneumoniae. Our results suggest that the undecaprenol monophosphate recycling pathway in S. pneumoniae could result from a functional redundancy between UppP, the PAP2-family protein Spr0434 and the DUF368-containing protein Spr0889.
Collapse
Affiliation(s)
- Linus Wilhelm
- Molecular Microbiology and Structural Biochemistry, UMR 5086, Université de Lyon, CNRS, 69007 Lyon, France
| | - Adrien Ducret
- Molecular Microbiology and Structural Biochemistry, UMR 5086, Université de Lyon, CNRS, 69007 Lyon, France
| | - Christophe Grangeasse
- Molecular Microbiology and Structural Biochemistry, UMR 5086, Université de Lyon, CNRS, 69007 Lyon, France
| |
Collapse
|
10
|
Kutnu M, İşlerel ET, Tunçbağ N, Özcengiz G. Comparative biological network analysis for differentially expressed proteins as a function of bacilysin biosynthesis in Bacillus subtilis. Integr Biol (Camb) 2022; 14:99-110. [PMID: 35901454 DOI: 10.1093/intbio/zyac010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 12/07/2021] [Accepted: 01/05/2022] [Indexed: 06/15/2023]
Abstract
The Gram-positive bacterium Bacillus subtilis produces a diverse range of secondary metabolites with different structures and activities. Among them, bacilysin is an enzymatically synthesized dipeptide that consists of L-alanine and L-anticapsin. Previous research by our group has suggested bacilysin's role as a pleiotropic molecule in its producer, B. subtilis PY79. However, the nature of protein interactions in the absence of bacilysin has not been defined. In the present work, we constructed a protein-protein interaction subnetwork by using Omics Integrator based on our recent comparative proteomics data obtained from a bacilysin-silenced strain, OGU1. Functional enrichment analyses on the resulting networks pointed to certain putatively perturbed pathways such as citrate cycle, quorum sensing and secondary metabolite biosynthesis. Various molecules, which were absent from the experimental data, were included in the final network. We believe that this study can guide further experiments in the identification and confirmation of protein-protein interactions in B. subtilis.
Collapse
Affiliation(s)
- Meltem Kutnu
- Department of Biological Sciences/Molecular Biology and Genetics, Middle East Technical University, Ankara 06800, Turkey
| | - Elif Tekin İşlerel
- Department of Biological Sciences/Molecular Biology and Genetics, Middle East Technical University, Ankara 06800, Turkey
- Department of Medical Microbiology, Faculty of Medicine, Maltepe University, Istanbul 34857, Turkey
| | - Nurcan Tunçbağ
- Department of Chemical and Biological Engineering, Koc University, Istanbul 34450, Turkey
| | - Gülay Özcengiz
- Department of Biological Sciences/Molecular Biology and Genetics, Middle East Technical University, Ankara 06800, Turkey
| |
Collapse
|
11
|
Shinjyo Y, Midorikawa N, Matsumoto T, Sugaya Y, Ozawa Y, Oana A, Horie C, Yoshikawa H, Takahashi Y, Hasegawa T, Asai K. Analysis of cell death in Bacillus subtilis caused by sesquiterpenes from Chrysopogon zizanioides (L.) Roberty. J GEN APPL MICROBIOL 2022; 68:62-70. [PMID: 35418537 DOI: 10.2323/jgam.2021.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Recently, the antibacterial effects of essential oils have been investigated in addition to their therapeutic purposes. Owing to their hydrophobic nature, they are thought to perturb the integrity of the bacterial cell membrane, leading to cell death. Against such antibiotic challenges, bacteria develop mechanisms for cell envelope stress responses (CESR). In Bacillus subtilis, a gram-positive sporulating soil bacterium, the extracytoplasmic function (ECF) sigma factor-mediated response system plays a pivotal role in CESR. Among them, σM is strongly involved in response to cell envelope stress, including a shortage of available bactoprenol. Vetiver essential oil, a product of Chrysopogon zizanioides (L.) Roberty root, is also known to possess bactericidal activity. σM was exclusively and strongly induced when the cells were exposed to Vetiver extract, and depletion of multi-ECF sigma factors (ΔsigM, ΔsigW, ΔsigX, and ΔsigV) enhanced sensitivity to it. From this quadruple mutant strain, the suppressor strains, which restored resistance to the bactericidal activity of Vetiver extract, emerged, although attempts to obtain resistant strains from the wild type did not succeed. Whole-genome resequencing of the suppressor strains and genetic analysis revealed inactivation of xseB or pnpA, which code for exodeoxyribonuclease or polynucleotide phosphorylase, respectively. This allowed the quadruple mutant strain to escape from cell death caused by Vetiver extract. Composition analysis suggested that the sesquiterpene, khusimol, might contribute to the bactericidal activity of the Vetiver extract.
Collapse
Affiliation(s)
- Yu Shinjyo
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Naoya Midorikawa
- Department of Chemistry, Graduate School of Science and Engineering, Saitama University
| | - Takashi Matsumoto
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture
| | - Yuki Sugaya
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Yoshiki Ozawa
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Ayumi Oana
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Chiaki Horie
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Hirofumi Yoshikawa
- Genome Research Center, NODAI Research Institute, Tokyo University of Agriculture.,Department of Bioscience, Tokyo University of Agriculture
| | - Yasuhiro Takahashi
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University
| | - Toshio Hasegawa
- Department of Chemistry, Graduate School of Science and Engineering, Saitama University
| | - Kei Asai
- Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University.,Department of Bioscience, Tokyo University of Agriculture
| |
Collapse
|
12
|
Prasher P, Sharma M. Medicinal chemistry of pyrophosphate mimics: A mini review. Drug Dev Res 2021; 83:3-15. [PMID: 34506652 DOI: 10.1002/ddr.21877] [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: 07/22/2021] [Revised: 08/20/2021] [Accepted: 08/24/2021] [Indexed: 12/21/2022]
Abstract
The pyrophosphate mimicking groups offer rational modification of the pyrophosphate-bearing natural substrates of the overexpressed enzymes that cause the onset of disease progression. Mainly, the modified substrate interacts differently with the enzyme active site eventually causing its deactivation, or provides the therapeutically active products at the completion of the catalytic cycle that contribute toward the inhibition of the target enzyme. Many of the pyrophosphate mimic-containing molecules serve as competitive or allosteric inhibitors of the target enzyme to achieve the desirable properties for the mitigation of the target enzyme's pathophysiology. This review presents an epigrammatic overview of the pyrophosphate mimics in medicinal chemistry.
Collapse
Affiliation(s)
- Parteek Prasher
- UGC Sponsored Centre for Advanced Studies, Department of Chemistry, Guru Nanak Dev University, Amritsar, India.,Department of Chemistry, University of Petroleum & Energy Studies, Dehradun, India
| | - Mousmee Sharma
- UGC Sponsored Centre for Advanced Studies, Department of Chemistry, Guru Nanak Dev University, Amritsar, India.,Department of Chemistry, Uttaranchal University, Dehradun, India
| |
Collapse
|
13
|
Fisher JF, Mobashery S. β-Lactams against the Fortress of the Gram-Positive Staphylococcus aureus Bacterium. Chem Rev 2021; 121:3412-3463. [PMID: 33373523 PMCID: PMC8653850 DOI: 10.1021/acs.chemrev.0c01010] [Citation(s) in RCA: 52] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The biological diversity of the unicellular bacteria-whether assessed by shape, food, metabolism, or ecological niche-surely rivals (if not exceeds) that of the multicellular eukaryotes. The relationship between bacteria whose ecological niche is the eukaryote, and the eukaryote, is often symbiosis or stasis. Some bacteria, however, seek advantage in this relationship. One of the most successful-to the disadvantage of the eukaryote-is the small (less than 1 μm diameter) and nearly spherical Staphylococcus aureus bacterium. For decades, successful clinical control of its infection has been accomplished using β-lactam antibiotics such as the penicillins and the cephalosporins. Over these same decades S. aureus has perfected resistance mechanisms against these antibiotics, which are then countered by new generations of β-lactam structure. This review addresses the current breadth of biochemical and microbiological efforts to preserve the future of the β-lactam antibiotics through a better understanding of how S. aureus protects the enzyme targets of the β-lactams, the penicillin-binding proteins. The penicillin-binding proteins are essential enzyme catalysts for the biosynthesis of the cell wall, and understanding how this cell wall is integrated into the protective cell envelope of the bacterium may identify new antibacterials and new adjuvants that preserve the efficacy of the β-lactams.
Collapse
Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame Indiana 46556, United States
| |
Collapse
|
14
|
Patel Y, Zhao H, Helmann JD. A regulatory pathway that selectively up-regulates elongasome function in the absence of class A PBPs. eLife 2020; 9:57902. [PMID: 32897856 PMCID: PMC7478892 DOI: 10.7554/elife.57902] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 08/22/2020] [Indexed: 12/28/2022] Open
Abstract
Bacteria surround themselves with peptidoglycan, an adaptable enclosure that contributes to cell shape and stability. Peptidoglycan assembly relies on penicillin-binding proteins (PBPs) acting in concert with SEDS-family transglycosylases RodA and FtsW, which support cell elongation and division respectively. In Bacillus subtilis, cells lacking all four PBPs with transglycosylase activity (aPBPs) are viable. Here, we show that the alternative sigma factor σI is essential in the absence of aPBPs. Defects in aPBP-dependent wall synthesis are compensated by σI-dependent upregulation of an MreB homolog, MreBH, which localizes the LytE autolysin to the RodA-containing elongasome complex. Suppressor analysis reveals that cells unable to activate this σI stress response acquire gain-of-function mutations in the essential histidine kinase WalK, which also elevates expression of sigI, mreBH and lytE. These results reveal compensatory mechanisms that balance the directional peptidoglycan synthesis arising from the elongasome complex with the more diffusive action of aPBPs.
Collapse
Affiliation(s)
- Yesha Patel
- Department of Microbiology, Cornell University, Ithaca, United States
| | - Heng Zhao
- Department of Microbiology, Cornell University, Ithaca, United States
| | - John D Helmann
- Department of Microbiology, Cornell University, Ithaca, United States
| |
Collapse
|
15
|
Lautenschläger N, Popp PF, Mascher T. Development of a novel heterologous β-lactam-specific whole-cell biosensor in Bacillus subtilis. J Biol Eng 2020; 14:21. [PMID: 32765644 PMCID: PMC7394692 DOI: 10.1186/s13036-020-00243-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Accepted: 07/16/2020] [Indexed: 11/10/2022] Open
Abstract
Background Whole-cell biosensors are a powerful and easy-to-use screening tool for the fast and sensitive detection of chemical compounds, such as antibiotics. β-Lactams still represent one of the most important antibiotic groups in therapeutic use. They interfere with late stages of the bacterial cell wall biosynthesis and result in irreversible perturbations of cell division and growth, ultimately leading to cell lysis. In order to simplify the detection of these antibiotics from solutions, solid media or directly from producing organisms, we aimed at developing a novel heterologous whole-cell biosensor in Bacillus subtilis, based on the β-lactam-induced regulatory system BlaR1/BlaI from Staphylococcus aureus. Results The BlaR1/BlaI system was heterologously expressed in B. subtilis and combined with the luxABCDE operon of Photorhabdus luminescens under control of the BlaR1/BlaI target promoter to measure the output of the biosensor. A combination of codon adaptation, constitutive expression of blaR1 and blaI and the allelic replacement of penP increased the inducer spectrum and dynamic range of the biosensor. β-Lactams from all four classes induced the target promoter PblaZ in a concentration-dependent manner, with a dynamic range of 7- to 53-fold. We applied our biosensor to a set of Streptomycetes soil isolates and demonstrated its potential to screen for the production of β-lactams. In addition to the successful implementation of a highly sensitive β-lactam biosensor, our results also provide the first experimental evidence to support previous suggestions that PenP functions as a β-lactamase in B. subtilis. Conclusion We have successfully established a novel heterologous whole-cell biosensor in B. subtilis that is highly sensitive for a broad spectrum of β-lactams from all four chemical classes. Therefore, it increases the detectable spectrum of compounds with respect to previous biosensor designs. Our biosensor can readily be applied for identifying β-lactams in liquid or on solid media, as well as for identifying potential β-lactam producers.
Collapse
Affiliation(s)
- Nina Lautenschläger
- Max Planck Unit for the Science of Pathogens, Berlin, Germany.,Institute of Microbiology, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany
| | - Philipp F Popp
- Institute of Microbiology, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany
| | - Thorsten Mascher
- Institute of Microbiology, Technische Universität Dresden, Zellescher Weg 20b, 01217 Dresden, Germany
| |
Collapse
|
16
|
Workman SD, Strynadka NCJ. A Slippery Scaffold: Synthesis and Recycling of the Bacterial Cell Wall Carrier Lipid. J Mol Biol 2020; 432:4964-4982. [PMID: 32234311 DOI: 10.1016/j.jmb.2020.03.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2020] [Revised: 03/18/2020] [Accepted: 03/25/2020] [Indexed: 01/20/2023]
Abstract
The biosynthesis of bacterial cell envelope polysaccharides such as peptidoglycan relies on the use of a dedicated carrier lipid both for the assembly of precursors at the cytoplasmic face of the plasma membrane and for the translocation of lipid linked oligosaccharides across the plasma membrane into the periplasmic space. This dedicated carrier lipid, undecaprenyl phosphate, results from the dephosphorylation of undecaprenyl pyrophosphate, which is generated de novo in the cytoplasm by undecaprenyl pyrophosphate synthase and released as a by-product when newly synthesized glycans are incorporated into the existing cell envelope. The de novo synthesis of undecaprenyl pyrophosphate has been thoroughly characterized from a structural and mechanistic standpoint; however, its dephosphorylation to the active carrier lipid form, both in the course of de novo synthesis and recycling, has only been begun to be studied in depth in recent years. This review provides an overview of bacterial carrier lipid synthesis and presents the current state of knowledge regarding bacterial carrier lipid recycling.
Collapse
Affiliation(s)
- Sean D Workman
- Department of Biochemistry and Molecular Biology and the Center for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3
| | - Natalie C J Strynadka
- Department of Biochemistry and Molecular Biology and the Center for Blood Research, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3.
| |
Collapse
|
17
|
BceAB-Type Antibiotic Resistance Transporters Appear To Act by Target Protection of Cell Wall Synthesis. Antimicrob Agents Chemother 2020; 64:AAC.02241-19. [PMID: 31871088 PMCID: PMC7038271 DOI: 10.1128/aac.02241-19] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 12/18/2019] [Indexed: 11/25/2022] Open
Abstract
Resistance against cell wall-active antimicrobial peptides in bacteria is often mediated by transporters. In low-GC-content Gram-positive bacteria, a common type of such transporters is BceAB-like systems, which frequently provide high-level resistance against peptide antibiotics that target intermediates of the lipid II cycle of cell wall synthesis. How a transporter can offer protection from drugs that are active on the cell surface, however, has presented researchers with a conundrum. Resistance against cell wall-active antimicrobial peptides in bacteria is often mediated by transporters. In low-GC-content Gram-positive bacteria, a common type of such transporters is BceAB-like systems, which frequently provide high-level resistance against peptide antibiotics that target intermediates of the lipid II cycle of cell wall synthesis. How a transporter can offer protection from drugs that are active on the cell surface, however, has presented researchers with a conundrum. Multiple theories have been discussed, ranging from removal of the peptides from the membrane and internalization of the drug for degradation to removal of the cellular target rather than the drug itself. To resolve this much-debated question, we here investigated the mode of action of the transporter BceAB of Bacillus subtilis. We show that it does not inactivate or import its substrate antibiotic bacitracin. Moreover, we present evidence that the critical factor driving transport activity is not the drug itself but instead the concentration of drug-target complexes in the cell. Our results, together with previously reported findings, lead us to propose that BceAB-type transporters act by transiently freeing lipid II cycle intermediates from the inhibitory grip of antimicrobial peptides and thus provide resistance through target protection of cell wall synthesis. Target protection has so far only been reported for resistance against antibiotics with intracellular targets, such as the ribosome. However, this mechanism offers a plausible explanation for the use of transporters as resistance determinants against cell wall-active antibiotics in Gram-positive bacteria where cell wall synthesis lacks the additional protection of an outer membrane.
Collapse
|
18
|
From Modules to Networks: a Systems-Level Analysis of the Bacitracin Stress Response in Bacillus subtilis. mSystems 2020; 5:5/1/e00687-19. [PMID: 32019833 PMCID: PMC7002115 DOI: 10.1128/msystems.00687-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Antibiotic resistance poses a major threat to global health, and systematic studies to understand the underlying resistance mechanisms are urgently needed. Although significant progress has been made in deciphering the mechanistic basis of individual resistance determinants, many bacterial species rely on the induction of a whole battery of resistance modules, and the complex regulatory networks controlling these modules in response to antibiotic stress are often poorly understood. In this work we combined experiments and theoretical modeling to decipher the resistance network of Bacillus subtilis against bacitracin, which inhibits cell wall biosynthesis in Gram-positive bacteria. We found a high level of cross-regulation between the two major resistance modules in response to bacitracin stress and quantified their effects on bacterial resistance. To rationalize our experimental data, we expanded a previously established computational model for the lipid II cycle through incorporating the quantitative action of the resistance modules. This led us to a systems-level description of the bacitracin stress response network that captures the complex interplay between resistance modules and the essential lipid II cycle of cell wall biosynthesis and accurately predicts the minimal inhibitory bacitracin concentration in all the studied mutants. With this, our study highlights how bacterial resistance emerges from an interlaced network of redundant homeostasis and stress response modules. Bacterial resistance against antibiotics often involves multiple mechanisms that are interconnected to ensure robust protection. So far, the knowledge about underlying regulatory features of those resistance networks is sparse, since they can hardly be determined by experimentation alone. Here, we present the first computational approach to elucidate the interplay between multiple resistance modules against a single antibiotic and how regulatory network structure allows the cell to respond to and compensate for perturbations of resistance. Based on the response of Bacillus subtilis toward the cell wall synthesis-inhibiting antibiotic bacitracin, we developed a mathematical model that comprehensively describes the protective effect of two well-studied resistance modules (BceAB and BcrC) on the progression of the lipid II cycle. By integrating experimental measurements of expression levels, the model accurately predicts the efficacy of bacitracin against the B. subtilis wild type as well as mutant strains lacking one or both of the resistance modules. Our study reveals that bacitracin-induced changes in the properties of the lipid II cycle itself control the interplay between the two resistance modules. In particular, variations in the concentrations of UPP, the lipid II cycle intermediate that is targeted by bacitracin, connect the effect of the BceAB transporter and the homeostatic response via BcrC to an overall resistance response. We propose that monitoring changes in pathway properties caused by a stressor allows the cell to fine-tune deployment of multiple resistance systems and may serve as a cost-beneficial strategy to control the overall response toward this stressor. IMPORTANCE Antibiotic resistance poses a major threat to global health, and systematic studies to understand the underlying resistance mechanisms are urgently needed. Although significant progress has been made in deciphering the mechanistic basis of individual resistance determinants, many bacterial species rely on the induction of a whole battery of resistance modules, and the complex regulatory networks controlling these modules in response to antibiotic stress are often poorly understood. In this work we combined experiments and theoretical modeling to decipher the resistance network of Bacillus subtilis against bacitracin, which inhibits cell wall biosynthesis in Gram-positive bacteria. We found a high level of cross-regulation between the two major resistance modules in response to bacitracin stress and quantified their effects on bacterial resistance. To rationalize our experimental data, we expanded a previously established computational model for the lipid II cycle through incorporating the quantitative action of the resistance modules. This led us to a systems-level description of the bacitracin stress response network that captures the complex interplay between resistance modules and the essential lipid II cycle of cell wall biosynthesis and accurately predicts the minimal inhibitory bacitracin concentration in all the studied mutants. With this, our study highlights how bacterial resistance emerges from an interlaced network of redundant homeostasis and stress response modules.
Collapse
|