1
|
Bouillet S, Bauer TS, Gottesman S. RpoS and the bacterial general stress response. Microbiol Mol Biol Rev 2024; 88:e0015122. [PMID: 38411096 PMCID: PMC10966952 DOI: 10.1128/mmbr.00151-22] [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: 02/28/2024] Open
Abstract
SUMMARYThe general stress response (GSR) is a widespread strategy developed by bacteria to adapt and respond to their changing environments. The GSR is induced by one or multiple simultaneous stresses, as well as during entry into stationary phase and leads to a global response that protects cells against multiple stresses. The alternative sigma factor RpoS is the central GSR regulator in E. coli and conserved in most γ-proteobacteria. In E. coli, RpoS is induced under conditions of nutrient deprivation and other stresses, primarily via the activation of RpoS translation and inhibition of RpoS proteolysis. This review includes recent advances in our understanding of how stresses lead to RpoS induction and a summary of the recent studies attempting to define RpoS-dependent genes and pathways.
Collapse
Affiliation(s)
- Sophie Bouillet
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, Bethesda, Maryland, USA
| | - Taran S. Bauer
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, Bethesda, Maryland, USA
| | - Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, NCI, Bethesda, Maryland, USA
| |
Collapse
|
2
|
Thani AB. DNA supercoiling and regulation of intrinsic β-lactamase in pathogenic Escherichia coli. Arch Microbiol 2023; 205:385. [PMID: 37980630 DOI: 10.1007/s00203-023-03716-4] [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: 07/03/2023] [Revised: 10/18/2023] [Accepted: 10/19/2023] [Indexed: 11/21/2023]
Abstract
This review addresses the involvement of DNA supercoiling in the development of virulence and antibiotic profiles for uropathogenic Escherichia coli and the emergence of new pathotypes such as strain ST131 (serotype O25:H4). The mechanism suggests a role for topoisomerase enzymes and associated mutations in altering the chromosomal supercoiling state and introducing the required DNA twists for expression of intrinsic β-lactamase by ampC and certain virulence factors. In Escherichia coli, constitutive hyperexpression of intrinsic ampC is associated with specific mutations in the promoter and attenuator regions. However, many reports have documented the involvement of slow growth interventions in the expression of intrinsic resistance determinants. There is evidence that a stationary phase transcriptional switch protein, "BolA," is involved in the expression of the intrinsic ampC gene under starvation conditions. The process involves changes in the activity of the enzyme "gyrase," which leads to a change in the chromosomal DNA topology. Consequently, the DNA is relaxed, and the expression of the bolA gene is upregulated. The evolution of the extraintestinal pathogenic E. coli strain ST131 has demonstrated successful adaptability to various stress conditions and conferred compensatory mutations that endowed the microbe with resistance to fluoroquinolones and β-lactams. The results of this study provided new insights into the evidence for the influence of DNA topology in the expression of virulence genes and various determinants of antibiotic resistance (e.g., the intrinsic ampC gene) in Escherichia coli pathotypes.
Collapse
Affiliation(s)
- Ali Bin Thani
- Department of Biology, College of Science, University of Bahrain, Zallaq, Kingdom of Bahrain.
| |
Collapse
|
3
|
Sanz-García F, Gil-Gil T, Laborda P, Blanco P, Ochoa-Sánchez LE, Baquero F, Martínez JL, Hernando-Amado S. Translating eco-evolutionary biology into therapy to tackle antibiotic resistance. Nat Rev Microbiol 2023; 21:671-685. [PMID: 37208461 DOI: 10.1038/s41579-023-00902-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/19/2023] [Indexed: 05/21/2023]
Abstract
Antibiotic resistance is currently one of the most important public health problems. The golden age of antibiotic discovery ended decades ago, and new approaches are urgently needed. Therefore, preserving the efficacy of the antibiotics currently in use and developing compounds and strategies that specifically target antibiotic-resistant pathogens is critical. The identification of robust trends of antibiotic resistance evolution and of its associated trade-offs, such as collateral sensitivity or fitness costs, is invaluable for the design of rational evolution-based, ecology-based treatment approaches. In this Review, we discuss these evolutionary trade-offs and how such knowledge can aid in informing combination or alternating antibiotic therapies against bacterial infections. In addition, we discuss how targeting bacterial metabolism can enhance drug activity and impair antibiotic resistance evolution. Finally, we explore how an improved understanding of the original physiological function of antibiotic resistance determinants, which have evolved to reach clinical resistance after a process of historical contingency, may help to tackle antibiotic resistance.
Collapse
Affiliation(s)
- Fernando Sanz-García
- Departamento de Microbiología, Medicina Preventiva y Salud Pública, Universidad de Zaragoza, Zaragoza, Spain
| | - Teresa Gil-Gil
- Centro Nacional de Biotecnología, CSIC, Darwin 3, Madrid, Spain
- Programa de Doctorado en Biociencias Moleculares, Universidad Autónoma de Madrid, Madrid, Spain
| | - Pablo Laborda
- Centro Nacional de Biotecnología, CSIC, Darwin 3, Madrid, Spain
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark
- Department of Clinical Microbiology, 9301, Rigshospitalet, Copenhagen, Denmark
| | - Paula Blanco
- Molecular Basis of Adaptation, Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain
- VISAVET Health Surveillance Centre, Universidad Complutense Madrid, Madrid, Spain
| | | | - Fernando Baquero
- Department of Microbiology, Hospital Universitario Ramón y Cajal (IRYCIS), CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | | | | |
Collapse
|
4
|
Avila‐Cobian LF, Hoshino H, Horsman ME, Nguyen VT, Qian Y, Feltzer R, Kim C, Hu DD, Champion MM, Fisher JF, Mobashery S. Amber-codon suppression for spatial localization and in vivo photoaffinity capture of the interactome of the Pseudomonas aeruginosa rare lipoprotein A lytic transglycosylase. Protein Sci 2023; 32:e4781. [PMID: 37703013 PMCID: PMC10536563 DOI: 10.1002/pro.4781] [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: 07/27/2023] [Revised: 09/06/2023] [Accepted: 09/11/2023] [Indexed: 09/14/2023]
Abstract
The 11 lytic transglycosylases of Pseudomonas aeruginosa have overlapping activities in the turnover of the cell-wall peptidoglycan. Rare lipoprotein A (RlpA) is distinct among the 11 by its use of only peptidoglycan lacking peptide stems. The spatial localization of RlpA and its interactome within P. aeruginosa are unknown. We employed suppression of introduced amber codons at sites in the rlpA gene for the introduction of the unnatural-amino-acids Νζ -[(2-azidoethoxy)carbonyl]-l-lysine (compound 1) and Nζ -[[[3-(3-methyl-3H-diazirin-3-yl)propyl]amino]carbonyl]-l-lysine (compound 2). In live P. aeruginosa, full-length RlpA incorporating compound 1 into its sequence was fluorescently tagged using strained-promoted alkyne-azide cycloaddition and examined by fluorescence microscopy. RlpA is present at low levels along the sidewall length of the bacterium, and at higher levels at the nascent septa of replicating bacteria. In intact P. aeruginosa, UV photolysis of full-length RlpA having compound 2 within its sequence generated a transient reactive carbene, which engaged in photoaffinity capture of neighboring proteins. Thirteen proteins were identified. Three of these proteins-PBP1a, PBP5, and MreB-are members of the bacterial divisome. The use of the complementary methodologies of non-canonical amino-acid incorporation, photoaffinity proximity analysis, and fluorescent microscopy confirm a dominant septal location for the RlpA enzyme of P. aeruginosa, as a divisome-associated activity. This accomplishment adds to the emerging recognition of the value of these methodologies for identification of the intracellular localization of bacterial proteins.
Collapse
Affiliation(s)
- Luis F. Avila‐Cobian
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Hidekazu Hoshino
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Mark E. Horsman
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Van T. Nguyen
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Yuanyuan Qian
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Rhona Feltzer
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Choon Kim
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Daniel D. Hu
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Matthew M. Champion
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Jed F. Fisher
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| | - Shahriar Mobashery
- Department of Chemistry and BiochemistryUniversity of Notre DameNotre DameIndianaUSA
| |
Collapse
|
5
|
English MA, Alcantar MA, Collins JJ. A self‐propagating, barcoded transposon system for the dynamic rewiring of genomic networks. Mol Syst Biol 2023:e11398. [DOI: 10.15252/msb.202211398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/29/2023] Open
|
6
|
Jiang M, Su YB, Ye JZ, Li H, Kuang SF, Wu JH, Li SH, Peng XX, Peng B. Ampicillin-controlled glucose metabolism manipulates the transition from tolerance to resistance in bacteria. SCIENCE ADVANCES 2023; 9:eade8582. [PMID: 36888710 PMCID: PMC9995076 DOI: 10.1126/sciadv.ade8582] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 02/07/2023] [Indexed: 05/31/2023]
Abstract
The mechanism(s) of how bacteria acquire tolerance and then resistance to antibiotics remains poorly understood. Here, we show that glucose abundance decreases progressively as ampicillin-sensitive strains acquire resistance to ampicillin. The mechanism involves that ampicillin initiates this event via targeting pts promoter and pyruvate dehydrogenase (PDH) to promote glucose transport and inhibit glycolysis, respectively. Thus, glucose fluxes into pentose phosphate pathway to generate reactive oxygen species (ROS) causing genetic mutations. Meanwhile, PDH activity is gradually restored due to the competitive binding of accumulated pyruvate and ampicillin, which lowers glucose level, and activates cyclic adenosine monophosphate (cAMP)/cAMP receptor protein (CRP) complex. cAMP/CRP negatively regulates glucose transport and ROS but enhances DNA repair, leading to ampicillin resistance. Glucose and Mn2+ delay the acquisition, providing an effective approach to control the resistance. The same effect is also determined in the intracellular pathogen Edwardsiella tarda. Thus, glucose metabolism represents a promising target to stop/delay the transition of tolerance to resistance.
Collapse
Affiliation(s)
- Ming Jiang
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Yu-bin Su
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
- Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Department of Biotechnology, College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Jin-zhou Ye
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
| | - Hui Li
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Su-fang Kuang
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
| | - Jia-han Wu
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
| | - Shao-hua Li
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
| | - Xuan-xian Peng
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| | - Bo Peng
- State Key Laboratory of Bio-Control, School of Life Sciences, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, Higher Education Mega Center, Guangzhou 510006, People’s Republic of China
- Laboratory for Marine Biology and Biotechnology, Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China
| |
Collapse
|
7
|
da Silva AA, Galego L, Arraiano CM. New Perspectives on BolA: A Still Mysterious Protein Connecting Morphogenesis, Biofilm Production, Virulence, Iron Metabolism, and Stress Survival. Microorganisms 2023; 11:microorganisms11030632. [PMID: 36985206 PMCID: PMC10051749 DOI: 10.3390/microorganisms11030632] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 02/09/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
The BolA-like protein family is widespread among prokaryotes and eukaryotes. BolA was originally described in E. coli as a gene induced in the stationary phase and in stress conditions. The BolA overexpression makes cells spherical. It was characterized as a transcription factor modulating cellular processes such as cell permeability, biofilm production, motility, and flagella assembly. BolA is important in the switch between motile and sedentary lifestyles having connections with the signaling molecule c-di-GMP. BolA was considered a virulence factor in pathogens such as Salmonella Typhimurium and Klebsiella pneumoniae and it promotes bacterial survival when facing stresses due to host defenses. In E. coli, the BolA homologue IbaG is associated with resistance to acidic stress, and in Vibrio cholerae, IbaG is important for animal cell colonization. Recently, it was demonstrated that BolA is phosphorylated and this modification is important for the stability/turnover of BolA and its activity as a transcription factor. The results indicate that there is a physical interaction between BolA-like proteins and the CGFS-type Grx proteins during the biogenesis of Fe-S clusters, iron trafficking and storage. We also review recent progress regarding the cellular and molecular mechanisms by which BolA/Grx protein complexes are involved in the regulation of iron homeostasis in eukaryotes and prokaryotes.
Collapse
|
8
|
Monothiol Glutaredoxin Is Essential for Oxidative Stress Protection and Virulence in Pseudomonas aeruginosa. Appl Environ Microbiol 2023; 89:e0171422. [PMID: 36533942 PMCID: PMC9888271 DOI: 10.1128/aem.01714-22] [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: 12/24/2022] Open
Abstract
Glutaredoxins (Grxs), ubiquitous redox enzymes belonging to the thioredoxin family, catalyze the reduction of thiol-disulfide exchange reactions in a glutathione-dependent manner. A Pseudomonas aeruginosa ΔgrxD mutant exhibited hypersensitivity to oxidative stress-generating agents, such as paraquat (PQ) and cumene hydroperoxide (CHP). In vitro studies showed that P. aeruginosa GrxD acts as an electron donor for organic hydroperoxide resistance enzyme (Ohr) during CHP degradation. The ectopic expression of iron-sulfur cluster ([Fe-S]) carrier proteins, including ErpA, IscA, and NfuA, complements the function of GrxD in the ΔgrxD mutant under PQ toxicity. Constitutively high expression of iscR, nfuA, tpx, and fprB was observed in the ΔgrxD mutant. These results suggest that GrxD functions as a [Fe-S] cluster carrier protein involved in [Fe-S] cluster maturation. Moreover, the ΔgrxD mutant demonstrates attenuated virulence in a Drosophila melanogaster host model. Altogether, the data shed light on the physiological role of GrxD in oxidative stress protection and virulence of the human pathogen, P. aeruginosa. IMPORTANCE Glutaredoxins (Grxs) are ubiquitous disulfide reductase enzymes. Monothiol Grxs, containing a CXXS motif, play an essential role in iron homeostasis and maturation of [Fe-S] cluster proteins in various organisms. We now establish that the human pathogen Pseudomonas aeruginosa GrxD is crucial for bacterial virulence, maturation of [Fe-S] clusters and facilitation of Ohr enzyme activity. GrxD contains a conserved signature monothiol motif (C29GFS), in which C29 is essential for its function in an oxidative stress protection. Our findings reveal the physiological roles of GrxD in oxidative stress protection and virulence of P. aeruginosa.
Collapse
|
9
|
Liang M, Fei Y, Wang Y, Chen W, Liu Z, Xu D, Shen H, Zhou H, Tang J. Integrative analysis of the role of BOLA2B in human pan-cancer. Front Genet 2023; 14:1077126. [PMID: 36923798 PMCID: PMC10008965 DOI: 10.3389/fgene.2023.1077126] [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: 10/22/2022] [Accepted: 02/10/2023] [Indexed: 03/03/2023] Open
Abstract
Objective: BOLA2B is a recently discovered protein-coding gene. Here, pan-cancer analysis was conducted to determine the expression patterns of BOLA2B and its impact on immune response, gene mutation, and possible molecular biological mechanisms in different tumors, together with investigating its potential usefulness for cancer prognosis. Methods: Data on BOLA2B expression and mutations were downloaded from TCGA and GTEx databases. Clinical survival data from TCGA were used to analyze the prognostic value of BOLA2B. TIMER and ESTIMATE algorithms were used to assess correlations between BOLA2B and tumor-infiltrating immune cells, immune cytokines, and immune scores. Results: BOLA2B was found to be highly expressed at both mRNA and protein levels in multiple tumors, where it was associated with worse overall survival (OS), disease-specific survival (DSS), and progression-free interval (PFI) in all cancers apart from ovarian cancer. BOLA2B was also found to be positively correlated with copy number variation (CNV), and mutations in TP53, TTN, and MUC16 were found to influence BOLA2B expression. Post-transcriptional modifications, including m5C, m1A, and m6A, were observed to regulate BOLA2B expression in all cancers. Functional analysis showed that BOLA2B was enriched in pathways associated with iron-sulfur cluster formation, mTOR-mediated autophagy, and cell cycle inhibition. Decreased BOLA2B expression induced the proliferation of breast cancer cells and G2/M cell cycle arrest. Conclusion: BOLA2B was found to be highly expressed in malignant tumors and could be used as a biomarker of poor prognosis in multiple cancers. Further investigation into BOLA2B's role and molecular functions in cancer would provide new insights for cancer diagnosis and treatment.
Collapse
Affiliation(s)
- Mingxing Liang
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yinjiao Fei
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Yalin Wang
- School of Clinical Medicine, Xuzhou Medical University, Xuzhou, China
| | - Wenquan Chen
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Zhen Liu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Di Xu
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Hongyu Shen
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Honglei Zhou
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jinhai Tang
- Department of General Surgery, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.,School of Clinical Medicine, Xuzhou Medical University, Xuzhou, China
| |
Collapse
|
10
|
Lou J, Cai J, Hu X, Liang Y, Sun Y, Zhu Y, Meng Q, Zhu T, Gao H, Yu Z, Yin J. The stringent starvation protein SspA modulates peptidoglycan synthesis by regulating the expression of peptidoglycan synthases. Mol Microbiol 2022; 118:716-730. [PMID: 36308522 DOI: 10.1111/mmi.14996] [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: 07/14/2022] [Revised: 10/19/2022] [Accepted: 10/22/2022] [Indexed: 01/18/2023]
Abstract
The peptidoglycan (PG) layer of bacterial cells is essential for maintaining the cell shape and survival of cells; therefore, the synthesis of PG needs to be spatiotemporally controlled. While it is well established that PG synthesis is mediated posttranslationally through interactions between PG synthases and their cognate partners, much less is known about the transcriptional regulation of genes encoding these synthases. Based on a previous finding that the Gram-negative bacterium Shewanella oneidensis lacking the prominent PG synthase exhibits impaired cell wall integrity, we performed genetic selections to isolate the suppressors. We discovered that disrupting the sspA gene encoding stringent starvation protein A (SspA) is sufficient to suppress compromised PG. SspA serves as a transcriptional repressor that regulates the expression of the two types of PG synthases, class A penicillin-binding proteins and SEDS/bPBP protein complexes. SspA is an RNA polymerase-associated protein, and its regulation involves interactions with the σ70 -RNAP complex and an antagonistic effect of H-NS, a global nucleoid-associated protein. We also present evidence that the regulation of PG synthases by SspA is conserved in Escherichia coli, adding a new dimension to the current understanding of PG synthesis and its regulation.
Collapse
Affiliation(s)
- Jie Lou
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Jingxiao Cai
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Xiao Hu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yanqun Liang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Yijuan Sun
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Yiling Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Qiu Meng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Tingheng Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Haichun Gao
- College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Zhiliang Yu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Jianhua Yin
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| |
Collapse
|
11
|
Divergent Effects of Peptidoglycan Carboxypeptidase DacA on Intrinsic β-Lactam and Vancomycin Resistance. Microbiol Spectr 2022; 10:e0173422. [PMID: 35758683 PMCID: PMC9430164 DOI: 10.1128/spectrum.01734-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Vancomycin and β-lactams are clinically important antibiotics that inhibit the formation of peptidoglycan cross-links, but their binding targets are different. The binding target of vancomycin is d-alanine-d-alanine (d-Ala-d-Ala), whereas that of β-lactam is penicillin-binding proteins (PBPs). In this study, we revealed the divergent effects of peptidoglycan (PG) carboxypeptidase DacA on vancomycin and β-lactam resistance in Escherichia coli and Bacillus subtilis. The deletion of DacA induced sensitivity to most β-lactams, whereas it induced strong resistance toward vancomycin. Notably, both phenotypes did not have a strong association with ld-transpeptidases, which are necessary for the formation of PG 3-3 cross-links and covalent bonds between PG and an Lpp outer membrane (OM) lipoprotein. Vancomycin resistance was induced by an increased amount of decoy d-Ala-d-Ala residues within PG, whereas β-lactam sensitivity was associated with physical interactions between DacA and PBPs. The presence of an OM permeability barrier strongly strengthened vancomycin resistance, but it significantly weakened β-lactam sensitivity. Collectively, our results revealed two distinct functions of DacA, which involved inverse modulation of bacterial resistance to clinically important antibiotics, β-lactams and vancomycin, and presented evidence for a link between DacA and PBPs. IMPORTANCE Bacterial PG hydrolases play important roles in various aspects of bacterial physiology, including cytokinesis, PG synthesis, quality control of PG, PG recycling, and stress adaptation. Of all the PG hydrolases, the role of PG carboxypeptidases is poorly understood, especially regarding their impacts on antibiotic resistance. We have revealed two distinct functions of PG carboxypeptidase DacA with respect to antibiotic resistance. The deletion of DacA led to sensitivity to most β-lactams, while it caused strong resistance to vancomycin. Our study provides novel insights into the roles of PG carboxypeptidases in the regulation of antibiotic resistance and a potential clue for the development of a drug to improve the clinical efficacy of β-lactam antibiotics.
Collapse
|
12
|
Nyongesa S, Chenal M, Bernet È, Coudray F, Veyrier FJ. Sequential markerless genetic manipulations of species from the Neisseria genus. Can J Microbiol 2022; 68:551-560. [PMID: 35512370 DOI: 10.1139/cjm-2022-0024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The development of simple and highly efficient strategies for genetic modifications are essential for post-genetic studies aimed at characterizing gene functions for various applications. We sought to develop a reliable system for Neisseria species that allows for both unmarked and accumulation of multiple genetic modifications in a single strain. In this work we developed and validated three-gene cassettes named RPLK and RPCC, comprising of an antibiotic resistance marker for positive selection, the phenotypic selection marker lacZ or mCherry, and the counter selection gene rpsL. These cassettes can be transformed with high efficiency across the Neisseria genus while significantly reducing the number of false positives compared to similar approaches. We exemplify the versatility and application of these systems by obtaining unmarked luminescent strains (knock-in) or mutants (knock-out) in different pathogenic and commensal species across the Neisseria genus in addition to the cumulative deletion of six loci in a single strain of Neisseria elongata.
Collapse
Affiliation(s)
- Sammy Nyongesa
- INRS, 14851, Centre Armand-Frappier Santé Biotechnologie, Quebec, Quebec, Canada;
| | - Martin Chenal
- INRS, 14851, Centre Armand-Frappier Santé Biotechnologie, Quebec, Quebec, Canada;
| | - Ève Bernet
- INRS, 14851, Centre Armand-Frappier Santé Biotechnologie, Quebec, Quebec, Canada;
| | - Florian Coudray
- INRS, 14851, Centre Armand-Frappier Santé Biotechnologie, Quebec, Quebec, Canada;
| | - Frédéric J Veyrier
- INRS, 14851, Centre Armand-Frappier Santé Biotechnologie, Quebec, Quebec, Canada;
| |
Collapse
|
13
|
Cell density-dependent antibiotic tolerance to inhibition of the elongation machinery requires fully functional PBP1B. Commun Biol 2022; 5:107. [PMID: 35115684 PMCID: PMC8813938 DOI: 10.1038/s42003-022-03056-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 01/18/2022] [Indexed: 01/20/2023] Open
Abstract
The peptidoglycan (PG) cell wall provides shape and structure to most bacteria. There are two systems to build PG in rod shaped organisms: the elongasome and divisome, which are made up of many proteins including the essential MreB and PBP2, or FtsZ and PBP3, respectively. The elongasome is responsible for PG insertion during cell elongation, while the divisome is responsible for septal PG insertion during division. We found that the main elongasome proteins, MreB and PBP2, can be inhibited without affecting growth rate in a quorum sensing-independent density-dependent manner. Before cells reach a particular cell density, inhibition of the elongasome results in different physiological responses, including intracellular vesicle formation and an increase in cell size. This inhibition of MreB or PBP2 can be compensated for by the presence of the class A penicillin binding protein, PBP1B. Furthermore, we found this density-dependent growth resistance to be specific for elongasome inhibition and was consistent across multiple Gram-negative rods, providing new areas of research into antibiotic treatment.
Collapse
|
14
|
Mohiuddin SG, Ghosh S, Ngo HG, Sensenbach S, Karki P, Dewangan NK, Angardi V, Orman MA. Cellular Self-Digestion and Persistence in Bacteria. Microorganisms 2021; 9:2269. [PMID: 34835393 PMCID: PMC8626048 DOI: 10.3390/microorganisms9112269] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 11/30/2022] Open
Abstract
Cellular self-digestion is an evolutionarily conserved process occurring in prokaryotic cells that enables survival under stressful conditions by recycling essential energy molecules. Self-digestion, which is triggered by extracellular stress conditions, such as nutrient depletion and overpopulation, induces degradation of intracellular components. This self-inflicted damage renders the bacterium less fit to produce building blocks and resume growth upon exposure to fresh nutrients. However, self-digestion may also provide temporary protection from antibiotics until the self-digestion-mediated damage is repaired. In fact, many persistence mechanisms identified to date may be directly or indirectly related to self-digestion, as these processes are also mediated by many degradative enzymes, including proteases and ribonucleases (RNases). In this review article, we will discuss the potential roles of self-digestion in bacterial persistence.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Mehmet A. Orman
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77004, USA; (S.G.M.); (S.G.); (H.G.N.); (S.S.); (P.K.); (N.K.D.); (V.A.)
| |
Collapse
|
15
|
Amemiya HM, Schroeder J, Freddolino PL. Nucleoid-associated proteins shape chromatin structure and transcriptional regulation across the bacterial kingdom. Transcription 2021; 12:182-218. [PMID: 34499567 PMCID: PMC8632127 DOI: 10.1080/21541264.2021.1973865] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 08/15/2021] [Accepted: 08/18/2021] [Indexed: 01/21/2023] Open
Abstract
Genome architecture has proven to be critical in determining gene regulation across almost all domains of life. While many of the key components and mechanisms of eukaryotic genome organization have been described, the interplay between bacterial DNA organization and gene regulation is only now being fully appreciated. An increasing pool of evidence has demonstrated that the bacterial chromosome can reasonably be thought of as chromatin, and that bacterial chromosomes contain transcriptionally silent and transcriptionally active regions analogous to heterochromatin and euchromatin, respectively. The roles played by histones in eukaryotic systems appear to be shared across a range of nucleoid-associated proteins (NAPs) in bacteria, which function to compact, structure, and regulate large portions of bacterial chromosomes. The broad range of extant NAPs, and the extent to which they differ from species to species, has raised additional challenges in identifying and characterizing their roles in all but a handful of model bacteria. Here we review the regulatory roles played by NAPs in several well-studied bacteria and use the resulting state of knowledge to provide a working definition for NAPs, based on their function, binding pattern, and expression levels. We present a screening procedure which can be applied to any species for which transcriptomic data are available. Finally, we note that NAPs tend to play two major regulatory roles - xenogeneic silencers and developmental regulators - and that many unrecognized potential NAPs exist in each bacterial species examined.
Collapse
Affiliation(s)
- Haley M. Amemiya
- University of Michigan Medical School, Ann Arbor, MI, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jeremy Schroeder
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Peter L. Freddolino
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| |
Collapse
|
16
|
Sargun A, Johnstone TC, Zhi H, Raffatellu M, Nolan EM. Enterobactin- and salmochelin-β-lactam conjugates induce cell morphologies consistent with inhibition of penicillin-binding proteins in uropathogenic Escherichia coli CFT073. Chem Sci 2021; 12:4041-4056. [PMID: 34163675 PMCID: PMC8179508 DOI: 10.1039/d0sc04337k] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 12/31/2020] [Indexed: 12/15/2022] Open
Abstract
The design and synthesis of narrow-spectrum antibiotics that target a specific bacterial strain, species, or group of species is a promising strategy for treating bacterial infections when the causative agent is known. In this work, we report the synthesis and evaluation of four new siderophore-β-lactam conjugates where the broad-spectrum β-lactam antibiotics cephalexin (Lex) and meropenem (Mem) are covalently attached to either enterobactin (Ent) or diglucosylated Ent (DGE) via a stable polyethylene glycol (PEG3) linker. These siderophore-β-lactam conjugates showed enhanced minimum inhibitory concentrations against Escherichia coli compared to the parent antibiotics. Uptake studies with uropathogenic E. coli CFT073 demonstrated that the DGE-β-lactams target the pathogen-associated catecholate siderophore receptor IroN. A comparative analysis of siderophore-β-lactams harboring ampicillin (Amp), Lex and Mem indicated that the DGE-Mem conjugate is advantageous because it targets IroN and exhibits low minimum inhibitory concentrations, fast time-kill kinetics, and enhanced stability to serine β-lactamases. Phase-contrast and fluorescence imaging of E. coli treated with the siderophore-β-lactam conjugates revealed cellular morphologies consistent with the inhibition of penicillin-binding proteins PBP3 (Ent/DGE-Amp/Lex) and PBP2 (Ent/DGE-Mem). Overall, this work illuminates the uptake and cell-killing activity of Ent- and DGE-β-lactam conjugates against E. coli and supports that native siderophore scaffolds provide the opportunity for narrowing the activity spectrum of antibiotics in clinical use and targeting pathogenicity.
Collapse
Affiliation(s)
- Artur Sargun
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA +1-617-452-2495
| | - Timothy C Johnstone
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA +1-617-452-2495
| | - Hui Zhi
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego La Jolla CA 92093 USA
| | - Manuela Raffatellu
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, University of California San Diego La Jolla CA 92093 USA
- Center for Microbiome Innovation, University of California San Diego La Jolla CA 92093 USA
- Chiba University-UC San Diego Center for Mucosal Immunology, Allergy, and Vaccines La Jolla CA 92093 USA
| | - Elizabeth M Nolan
- Department of Chemistry, Massachusetts Institute of Technology Cambridge MA 02139 USA +1-617-452-2495
| |
Collapse
|
17
|
Garde S, Chodisetti PK, Reddy M. Peptidoglycan: Structure, Synthesis, and Regulation. EcoSal Plus 2021; 9:eESP-0010-2020. [PMID: 33470191 PMCID: PMC11168573 DOI: 10.1128/ecosalplus.esp-0010-2020] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Peptidoglycan is a defining feature of the bacterial cell wall. Initially identified as a target of the revolutionary beta-lactam antibiotics, peptidoglycan has become a subject of much interest for its biology, its potential for the discovery of novel antibiotic targets, and its role in infection. Peptidoglycan is a large polymer that forms a mesh-like scaffold around the bacterial cytoplasmic membrane. Peptidoglycan synthesis is vital at several stages of the bacterial cell cycle: for expansion of the scaffold during cell elongation and for formation of a septum during cell division. It is a complex multifactorial process that includes formation of monomeric precursors in the cytoplasm, their transport to the periplasm, and polymerization to form a functional peptidoglycan sacculus. These processes require spatio-temporal regulation for successful assembly of a robust sacculus to protect the cell from turgor and determine cell shape. A century of research has uncovered the fundamentals of peptidoglycan biology, and recent studies employing advanced technologies have shed new light on the molecular interactions that govern peptidoglycan synthesis. Here, we describe the peptidoglycan structure, synthesis, and regulation in rod-shaped bacteria, particularly Escherichia coli, with a few examples from Salmonella and other diverse organisms. We focus on the pathway of peptidoglycan sacculus elongation, with special emphasis on discoveries of the past decade that have shaped our understanding of peptidoglycan biology.
Collapse
Affiliation(s)
- Shambhavi Garde
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Pavan Kumar Chodisetti
- These authors contributed equally
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| | - Manjula Reddy
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India 500007
| |
Collapse
|
18
|
Transcriptome-based design of antisense inhibitors potentiates carbapenem efficacy in CRE Escherichia coli. Proc Natl Acad Sci U S A 2020; 117:30699-30709. [PMID: 33199638 DOI: 10.1073/pnas.1922187117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
In recent years, the prevalence of carbapenem-resistant Enterobacteriaceae (CRE) has risen substantially, and the study of CRE resistance mechanisms has become increasingly important for antibiotic development. Although much research has focused on genomic resistance factors, relatively few studies have examined CRE pathogens through changes in gene expression. In this study, we examined the gene expression profile of a CRE Escherichia coli clinical isolate that is sensitive to meropenem but resistant to ertapenem to explore transcriptomic contributions to resistance and to identify gene knockdown targets for carbapenem potentiation. We sequenced total and short RNA to analyze the gene expression response to ertapenem or meropenem treatment and found significant expression changes in genes related to motility, maltodextrin metabolism, the formate hydrogenlyase complex, and the general stress response. To validate these findings, we used our laboratory's Facile Accelerated Specific Therapeutic (FAST) platform to create antisense peptide nucleic acids (PNAs), gene-specific molecules designed to inhibit protein translation. PNAs were designed to inhibit the pathways identified in our transcriptomic analysis, and each PNA was then tested in combination with each carbapenem to assess its effect on the antibiotics' minimum inhibitory concentrations. We observed significant PNA-antibiotic interaction with five different PNAs across six combinations. Inhibition of the genes hycA, dsrB, and bolA potentiated carbapenem efficacy in CRE E. coli, whereas inhibition of the genes flhC and ygaC conferred added resistance. Our results identify resistance factors and demonstrate that transcriptomic analysis is a potent tool for designing antibiotic PNA.
Collapse
|
19
|
Galego L, Barahona S, Romão CV, Arraiano CM. Phosphorylation status of BolA affects its role in transcription and biofilm development. FEBS J 2020; 288:961-979. [PMID: 32535996 DOI: 10.1111/febs.15447] [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: 11/08/2019] [Revised: 02/28/2020] [Accepted: 06/08/2020] [Indexed: 11/30/2022]
Abstract
BolA has been characterized as an important transcriptional regulator, which is induced in stationary phase of growth, and in response to several stresses. In Escherichia coli, its cellular function is associated with cell wall synthesis and division, morphology, permeability, motility and biofilm formation. Phosphorylation has been widely described as one of the most important events involved in the modulation of the activity of many transcription factors. In the present work, we have demonstrated in vivo and by mass spectrometry that BolA is phosphorylated in four highly conserved protein positions: S26, S45, T81 and S95. S95 is located in the C terminus unstructured region of the protein, and the other three sites are in the DNA-binding domain. These positions were mutated to nonphosphorylated residues, and their effects were investigated on different known BolA functions. Using northern blot experiments, we showed that the regulation of the expression of these Ser/Thr BolA mutants is performed at the post-translational level. Western blot results revealed that the stability/turnover of the mutated BolA proteins is differently affected depending on the dephosphorylated residue. Moreover, we provide evidences that phosphorylation events are crucial in the modulation of BolA activity as a transcription factor and as a regulator of cell morphology and biofilm development. Here, we propose that phosphorylation affects BolA downstream functions and discuss the possible significance of these phosphoresidues in the protein structure, stability, dimerization and function as a transcription factor.
Collapse
Affiliation(s)
- Lisete Galego
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Susana Barahona
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Célia V Romão
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Cecília M Arraiano
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| |
Collapse
|
20
|
Pan X, Sun C, Tang M, Liu C, Zhang J, You J, Osire T, Sun Y, Zhao Y, Xu M, Yang T, Rao Z. Loss of Serine-Type D-Ala-D-Ala Carboxypeptidase DacA Enhances Prodigiosin Production in Serratia marcescens. Front Bioeng Biotechnol 2019; 7:367. [PMID: 31850328 PMCID: PMC6901396 DOI: 10.3389/fbioe.2019.00367] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Accepted: 11/13/2019] [Indexed: 12/11/2022] Open
Abstract
Serratia marcescens, a gram-negative bacterium, found in a wide range of ecological niches can produce several high-value products, including prodigiosin, althiomycin, and serratamolide. Among them, prodigiosin has attracted attention due to its immunosuppressive, antimicrobial, and anticancer properties. However, the regulatory mechanisms behind prodigiosin synthesis in Serratia marcescens remains limited. Here, a transposon mutant library was constructed to identify the genes related to prodigiosin synthesis, and BVG90_02415 gene encoding a peptidoglycan synthesizing enzyme D-Ala-D-Ala carboxypeptidase DacA was found to negatively regulates prodigiosin synthesis. Quantitative measurements revealed that disruption of dacA increased prodigiosin production 1.46-fold that of the wild-type strain JNB5-1 in fermentation medium. By comparing differences in cell growth, pigA gene expression level, cell morphology, membrane permeability, and intracellular prodigiosin concentration between wild-type strain JNB5-1 and dacA mutant SK4-72, results revealed that the mechanism for hyper-producing of prodigiosin by the dacA mutant was probably that dacA disruption enhanced prodigiosin leakage, which in turn alleviated feedback inhibition of prodigiosin and increased expression of pig gene cluster. Collectively, this work provides a novel insight into regulatory mechanisms of prodigiosin synthesis and uncovers new roles of DacA protein in regulating cell growth, cell morphology, and membrane permeability in Serratia marcescens. Finally, this study offers a new strategy for improving production of high-value compounds in Serratia marcescens.
Collapse
Affiliation(s)
- Xuewei Pan
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Changhao Sun
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Mi Tang
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Chao Liu
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Jianing Zhang
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Jiajia You
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Tolbert Osire
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Yang Sun
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Youxi Zhao
- Biochemical Engineering College, Beijing Union University, Beijing, China
| | - Meijuan Xu
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Taowei Yang
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Zhiming Rao
- Key Laboratory of Industrial Biotechnology of the Ministry of Education, Laboratory of Applied Microorganisms and Metabolic Engineering, School of Biotechnology, Jiangnan University, Wuxi, China
| |
Collapse
|
21
|
King T, Vockler CJ, Allnutt TR, Fegan N. Transcriptomic response of Escherichia coli O157 isolates on meat: Comparison between a typical Australian isolate from cattle and a pathogenic clinical isolate. Food Microbiol 2019; 82:378-387. [DOI: 10.1016/j.fm.2019.03.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 02/25/2019] [Accepted: 03/07/2019] [Indexed: 02/02/2023]
|
22
|
Abstract
BolA family proteins are conserved in Gram-negative bacteria and many eukaryotes. While diverse cellular phenotypes have been linked to this protein family, the molecular pathways through which these proteins mediate their effects are not well described. Here, we investigated the roles of BolA family proteins in Vibrio cholerae, the cholera pathogen. Like Escherichia coli, V. cholerae encodes two BolA proteins, BolA and IbaG. However, in marked contrast to E. coli, where bolA is linked to cell shape and ibaG is not, in V. cholerae, bolA mutants lack morphological defects, whereas ibaG proved critical for the generation and/or maintenance of the pathogen's morphology. Notably, the bizarre-shaped, multipolar, elongated, and wide cells that predominated in exponential-phase ΔibaG V. cholerae cultures were not observed in stationary-phase cultures. The V. cholerae ΔibaG mutant exhibited increased sensitivity to cell envelope stressors, including cell wall-acting antibiotics and bile, and was defective in intestinal colonization. ΔibaG V. cholerae had reduced peptidoglycan and lipid II and altered outer membrane lipids, likely contributing to the mutant's morphological defects and sensitivity to envelope stressors. Transposon insertion sequencing analysis of ibaG's genetic interactions suggested that ibaG is involved in several processes involved in the generation and homeostasis of the cell envelope. Furthermore, copurification studies revealed that IbaG interacts with proteins containing iron-sulfur clusters or involved in their assembly. Collectively, our findings suggest that V. cholerae IbaG controls cell morphology and cell envelope integrity through its role in biogenesis or trafficking of iron-sulfur cluster proteins.IMPORTANCE BolA-like proteins are conserved across prokaryotes and eukaryotes. These proteins have been linked to a variety of phenotypes, but the pathways and mechanisms through which they act have not been extensively characterized. Here, we unraveled the role of the BolA-like protein IbaG in the cholera pathogen Vibrio cholerae The absence of IbaG was associated with dramatic changes in cell morphology, sensitivity to envelope stressors, and intestinal colonization defects. IbaG was found to be required for biogenesis of several components of the V. cholerae cell envelope and to interact with numerous iron-sulfur cluster-containing proteins and factors involved in their assembly. Thus, our findings suggest that IbaG governs V. cholerae cell shape and cell envelope homeostasis through its effects on iron-sulfur proteins and associated pathways. The diversity of processes involving iron-sulfur-containing proteins is likely a factor underlying the range of phenotypes associated with BolA family proteins.
Collapse
|
23
|
Godinez WJ, Chan H, Hossain I, Li C, Ranjitkar S, Rasper D, Simmons RL, Zhang X, Feng BY. Morphological Deconvolution of Beta-Lactam Polyspecificity in E. coli. ACS Chem Biol 2019; 14:1217-1226. [PMID: 31184469 DOI: 10.1021/acschembio.9b00141] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Beta-lactams comprise one of the earliest classes of antibiotic therapies. These molecules covalently inhibit enzymes from the family of penicillin-binding proteins (PBPs), which are essential in construction of the bacterial cell wall. As a result, beta-lactams cause striking changes to cellular morphology, the nature of which varies by the range of PBPs simultaneously engaged in the cell. The traditional method of exploring beta-lactam polyspecificity is a gel-based binding assay which is low-throughput and typically is run ex situ in cell extracts. Here, we describe a medium-throughput, image-based assay combined with machine learning methods to automatically profile the activity of beta-lactams in E. coli cells. By testing for morphological change across a panel of strains with perturbations to individual PBP enzymes, our approach automatically and quantifiably relates different beta-lactam antibiotics according to their preferences for individual PBPs in cells. We show the potential of our approach for guiding the design of novel inhibitors toward different PBP-binding profiles by predicting the mechanisms of two recently reported PBP inhibitors.
Collapse
Affiliation(s)
- William J. Godinez
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, Basel, Switzerland
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States
| | - Helen Chan
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States
| | - Imtiaz Hossain
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Cindy Li
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States
| | - Srijan Ranjitkar
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States
| | - Dita Rasper
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States
| | - Robert L. Simmons
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States
| | - Xian Zhang
- Chemical Biology and Therapeutics, Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Brian Y. Feng
- Infectious Diseases, Novartis Institutes for BioMedical Research, Emeryville, California, United States
| |
Collapse
|
24
|
Chakraborty S, Kenney LJ. A New Role of OmpR in Acid and Osmotic Stress in Salmonella and E. coli. Front Microbiol 2018; 9:2656. [PMID: 30524381 PMCID: PMC6262077 DOI: 10.3389/fmicb.2018.02656] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/17/2018] [Indexed: 12/24/2022] Open
Abstract
Bacteria survive and respond to diverse environmental conditions and during infection inside the host by systematic regulation of stress response genes. E. coli and S. Typhimurium can undergo large changes in intracellular osmolality (up to 1.8 Osmol/kg) and can tolerate cytoplasmic acidification to at least pHi 5.6. Recent analyses of single cells challenged a long held view that bacteria respond to extracellular acid stress by rapid acidification followed by a rapid recovery. It is now appreciated that both S. Typhimurium and E. coli maintain an acidic cytoplasm through the actions of the outer membrane protein regulator OmpR via its regulation of distinct signaling pathways. However, a comprehensive comparison of OmpR regulons between S. Typhimurium and E. coli is lacking. In this study, we examined the expression profiles of wild-type and ompR null strains of the intracellular pathogen S. Typhimurium and a commensal E. coli in response to acid and osmotic stress. Herein, we classify distinct OmpR regulons and also identify shared OmpR regulatory pathways between S. Typhimurium and E. coli in response to acid and osmotic stress. Our study establishes OmpR as a key regulator of bacterial virulence, growth and metabolism, in addition to its role in regulating outer membrane proteins.
Collapse
Affiliation(s)
- Smarajit Chakraborty
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Linda J. Kenney
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
- Department of Biochemistry, National University of Singapore, Singapore, Singapore
- Departments of Microbiology and Immunology, University of Illinois at Chicago, Chicago, IL, United States
- Bioengineering, University of Illinois at Chicago, Chicago, IL, United States
- Jesse Brown Veterans Administration Medical Center, Chicago, IL, United States
- *Correspondence: Linda J. Kenney,
| |
Collapse
|
25
|
Dik DA, Fisher JF, Mobashery S. Cell-Wall Recycling of the Gram-Negative Bacteria and the Nexus to Antibiotic Resistance. Chem Rev 2018; 118:5952-5984. [PMID: 29847102 PMCID: PMC6855303 DOI: 10.1021/acs.chemrev.8b00277] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The importance of the cell wall to the viability of the bacterium is underscored by the breadth of antibiotic structures that act by blocking key enzymes that are tasked with cell-wall creation, preservation, and regulation. The interplay between cell-wall integrity, and the summoning forth of resistance mechanisms to deactivate cell-wall-targeting antibiotics, involves exquisite orchestration among cell-wall synthesis and remodeling and the detection of and response to the antibiotics through modulation of gene regulation by specific effectors. Given the profound importance of antibiotics to the practice of medicine, the assertion that understanding this interplay is among the most fundamentally important questions in bacterial physiology is credible. The enigmatic regulation of the expression of the AmpC β-lactamase, a clinically significant and highly regulated resistance response of certain Gram-negative bacteria to the β-lactam antibiotics, is the exemplar of this challenge. This review gives a current perspective to this compelling, and still not fully solved, 35-year enigma.
Collapse
Affiliation(s)
- David A. Dik
- Department of Chemistry and Biochemistry, McCourtney Hall, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - 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
|
26
|
Iyer S, Le D, Park BR, Kim M. Distinct mechanisms coordinate transcription and translation under carbon and nitrogen starvation in Escherichia coli. Nat Microbiol 2018; 3:741-748. [PMID: 29760462 DOI: 10.1038/s41564-018-0161-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Accepted: 04/16/2018] [Indexed: 11/09/2022]
Abstract
Bacteria adapt to environmental stress by producing proteins that provide stress protection. However, stress can severely perturb the kinetics of gene expression, disrupting protein production. Here, we characterized how Escherichia coli mitigates such perturbations under nutrient stress through the kinetic coordination of transcription and translation. We observed that, when translation became limiting under nitrogen starvation, transcription elongation slowed accordingly. This slowdown was mediated by (p)ppGpp, the alarmone whose primary role is thought to be promoter regulation. This kinetic coordination by (p)ppGpp was critical for the robust synthesis of gene products. Surprisingly, under carbon starvation, (p)ppGpp was dispensable for robust synthesis. Characterization of the underlying kinetics revealed that under carbon starvation, transcription became limiting, and translation aided transcription elongation. This mechanism naturally coordinated transcription with translation, alleviating the need for (p)ppGpp as a mediator. These contrasting mechanisms for coordination resulted in the condition-dependent effects of (p)ppGpp on global protein synthesis and starvation survival. Our findings reveal a kinetic aspect of gene expression plasticity, establishing (p)ppGpp as a condition-dependent global effector of gene expression.
Collapse
Affiliation(s)
- Sukanya Iyer
- Department of Physics, Emory University, Atlanta, GA, USA
| | - Dai Le
- Department of Physics, Emory University, Atlanta, GA, USA
| | - Bo Ryoung Park
- Department of Physics, Emory University, Atlanta, GA, USA
| | - Minsu Kim
- Department of Physics, Emory University, Atlanta, GA, USA. .,Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, GA, USA. .,Emory Antibiotic Resistance Center, Emory University, Atlanta, GA, USA.
| |
Collapse
|
27
|
Abstract
How cells establish, maintain, and modulate size has always been an area of great interest and fascination. Until recently, technical limitations curtailed our ability to understand the molecular basis of bacterial cell size control. In the past decade, advances in microfluidics, imaging, and high-throughput single-cell analysis, however, have led to a flurry of work revealing size to be a highly complex trait involving the integration of three core aspects of bacterial physiology: metabolism, growth, and cell cycle progression.
Collapse
Affiliation(s)
- Corey S Westfall
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130; ,
| | - Petra Anne Levin
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130; ,
| |
Collapse
|
28
|
Stress Response Protein BolA Influences Fitness and Promotes Salmonella enterica Serovar Typhimurium Virulence. Appl Environ Microbiol 2018; 84:AEM.02850-17. [PMID: 29439986 DOI: 10.1128/aem.02850-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 02/01/2018] [Indexed: 11/20/2022] Open
Abstract
The intracellular pathogen Salmonella enterica serovar Typhimurium has emerged as a major cause of foodborne illness, representing a severe clinical and economic concern worldwide. The capacity of this pathogen to efficiently infect and survive inside the host depends on its ability to synchronize a complex network of virulence mechanisms. Therefore, the identification of new virulence determinants has become of paramount importance in the search of new targets for drug development. BolA-like proteins are widely conserved in all kingdoms of life. In Escherichia coli, this transcription factor has a critical regulatory role in several mechanisms that are tightly related to bacterial virulence. Therefore, in the present work we used the well-established infection model Galleria mellonella to evaluate the role of BolA protein in S Typhimurium virulence. We have shown that BolA is an important player in S Typhimurium pathogenesis. Specifically, the absence of BolA leads to a defective virulence capacity that is most likely related to the remarkable effect of this protein on S Typhimurium evasion of the cellular response. Furthermore, it was demonstrated that BolA has a critical role in bacterial survival under harsh conditions since BolA conferred protection against acidic and oxidative stress. Hence, we provide evidence that BolA is a determining factor in the ability of Salmonella to survive and overcome host defense mechanisms, and this is an important step in progress to an understanding of the pathways underlying bacterial virulence.IMPORTANCE BolA has been described as an important protein for survival in the late stages of bacterial growth and under harsh environmental conditions. High levels of BolA in stationary phase and under stresses have been connected with a plethora of phenotypes, strongly suggesting its important role as a master regulator. Here, we show that BolA is a determining factor in the ability of Salmonella to survive and overcome host defense mechanisms, and this is an important step in progress to an understanding of the pathways underlying bacterial virulence. This work constitutes a relevant step toward an understanding of the role of BolA protein and may have an important impact on future studies in other organisms. Therefore, this study is of utmost importance for understanding the genetic and molecular bases involved in the regulation of Salmonella virulence and may contribute to future industrial and public health care applications.
Collapse
|
29
|
Dhar S, Kumari H, Balasubramanian D, Mathee K. Cell-wall recycling and synthesis in Escherichia coli and Pseudomonas aeruginosa – their role in the development of resistance. J Med Microbiol 2018; 67:1-21. [DOI: 10.1099/jmm.0.000636] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Supurna Dhar
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Hansi Kumari
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | | | - Kalai Mathee
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
- Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| |
Collapse
|
30
|
Zhao H, Patel V, Helmann JD, Dörr T. Don't let sleeping dogmas lie: new views of peptidoglycan synthesis and its regulation. Mol Microbiol 2017; 106:847-860. [PMID: 28975672 DOI: 10.1111/mmi.13853] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2017] [Indexed: 12/24/2022]
Abstract
Bacterial cell wall synthesis is the target for some of our most powerful antibiotics and has thus been the subject of intense research focus for more than 50 years. Surprisingly, we still lack a fundamental understanding of how bacteria build, maintain and expand their cell wall. Due to technical limitations, directly testing hypotheses about the coordination and biochemistry of cell wall synthesis enzymes or architecture has been challenging, and interpretation of data has therefore often relied on circumstantial evidence and implicit assumptions. A number of recent papers have exploited new technologies, like single molecule tracking and real-time, high resolution temporal mapping of cell wall synthesis processes, to address fundamental questions of bacterial cell wall biogenesis. The results have challenged established dogmas and it is therefore timely to integrate new data and old observations into a new model of cell wall biogenesis in rod-shaped bacteria.
Collapse
Affiliation(s)
- Heng Zhao
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA
| | - Vaidehi Patel
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA
| | - John D Helmann
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA
| | - Tobias Dörr
- Department of Microbiology, Cornell University, Ithaca, NY 14853-8101, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| |
Collapse
|
31
|
Novel RpoS-Dependent Mechanisms Strengthen the Envelope Permeability Barrier during Stationary Phase. J Bacteriol 2016; 199:JB.00708-16. [PMID: 27821607 DOI: 10.1128/jb.00708-16] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 10/28/2016] [Indexed: 12/22/2022] Open
Abstract
Gram-negative bacteria have effective methods of excluding toxic compounds, including a largely impermeable outer membrane (OM) and a range of efflux pumps. Furthermore, when cells become nutrient limited, RpoS enacts a global expression change providing cross-protection against many stresses. Here, we utilized sensitivity to an anionic detergent (sodium dodecyl sulfate [SDS]) to probe changes occurring to the cell's permeability barrier during nutrient limitation. Escherichia coli is resistant to SDS whether cells are actively growing, carbon limited, or nitrogen limited. In actively growing cells, this resistance depends on the AcrAB-TolC efflux pump; however, this pump is not necessary for protection under either carbon-limiting or nitrogen-limiting conditions, suggesting an alternative mechanism(s) of SDS resistance. In carbon-limited cells, RpoS-dependent pathways lessen the permeability of the OM, preventing the necessity for efflux. In nitrogen-limited but not carbon-limited cells, the loss of rpoS can be completely compensated for by the AcrAB-TolC efflux pump. We suggest that this difference simply reflects the fact that nitrogen-limited cells have access to a metabolizable energy (carbon) source that can efficiently power the efflux pump. Using a transposon mutant pool sequencing (Tn-Seq) approach, we identified three genes, sanA, dacA, and yhdP, that are necessary for RpoS-dependent SDS resistance in carbon-limited stationary phase. Using genetic analysis, we determined that these genes are involved in two different envelope-strengthening pathways. These genes have not previously been implicated in stationary-phase stress responses. A third novel RpoS-dependent pathway appears to strengthen the cell's permeability barrier in nitrogen-limited cells. Thus, though cells remain phenotypically SDS resistant, SDS resistance mechanisms differ significantly between growth states. IMPORTANCE Gram-negative bacteria are intrinsically resistant to detergents and many antibiotics due to synergistic activities of a strong outer membrane (OM) permeability barrier and efflux pumps that capture and expel toxic molecules eluding the barrier. When the bacteria are depleted of an essential nutrient, a program of gene expression providing cross-protection against many stresses is induced. Whether this program alters the OM to further strengthen the barrier is unknown. Here, we identify novel pathways dependent on the master regulator of stationary phase that further strengthen the OM permeability barrier during nutrient limitation, circumventing the need for efflux pumps. Decreased permeability of nutrient-limited cells to toxic compounds has important implications for designing new antibiotics capable of targeting Gram-negative bacteria that may be in a growth-limited state.
Collapse
|
32
|
Peters K, Kannan S, Rao VA, Biboy J, Vollmer D, Erickson SW, Lewis RJ, Young KD, Vollmer W. The Redundancy of Peptidoglycan Carboxypeptidases Ensures Robust Cell Shape Maintenance in Escherichia coli. mBio 2016; 7:e00819-16. [PMID: 27329754 PMCID: PMC4916385 DOI: 10.1128/mbio.00819-16] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 05/13/2016] [Indexed: 12/03/2022] Open
Abstract
UNLABELLED Peptidoglycan (PG) is an essential structural component of the bacterial cell wall and maintains the integrity and shape of the cell by forming a continuous layer around the cytoplasmic membrane. The thin PG layer of Escherichia coli resides in the periplasm, a unique compartment whose composition and pH can vary depending on the local environment of the cell. Hence, the growth of the PG layer must be sufficiently robust to allow cell growth and division under different conditions. We have analyzed the PG composition of 28 mutants lacking multiple PG enzymes (penicillin-binding proteins [PBPs]) after growth in acidic or near-neutral-pH media. Statistical analysis of the muropeptide profiles identified dd-carboxypeptidases (DD-CPases) that were more active in cells grown at acidic pH. In particular, the absence of the DD-CPase PBP6b caused a significant increase in the pentapeptide content of PG as well as morphological defects when the cells were grown at acidic pH. Other DD-CPases (PBP4, PBP4b, PBP5, PBP6a, PBP7, and AmpH) and the PG synthase PBP1B made a smaller or null contribution to the pentapeptide-trimming activity at acidic pH. We solved the crystal structure of PBP6b and also demonstrated that the enzyme is more stable and has a lower Km at acidic pH, explaining why PBP6b is more active at low pH. Hence, PBP6b is a specialized DD-CPase that contributes to cell shape maintenance at low pH, and E. coli appears to utilize redundant DD-CPases for normal growth under different conditions. IMPORTANCE Escherichia coli requires peptidoglycan dd-carboxypeptidases to maintain cell shape by controlling the amount of pentapeptide substrates available to the peptidoglycan synthetic transpeptidases. Why E. coli has eight, seemingly redundant dd-carboxypeptidases has remained unknown. We now show that one of these dd-carboxypeptidases, PBP6b, is important for cell shape maintenance in acidic growth medium, consistent with the higher activity and stability of the enzyme at low pH. Hence, the presence of multiple dd-carboxypeptidases with different enzymatic properties may allow E. coli to maintain a normal cell shape under various growth conditions.
Collapse
Affiliation(s)
- Katharina Peters
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Suresh Kannan
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Vincenzo A Rao
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jacob Biboy
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Daniela Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Stephen W Erickson
- Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Richard J Lewis
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Kevin D Young
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Waldemar Vollmer
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| |
Collapse
|
33
|
Gully D, Gargani D, Bonaldi K, Grangeteau C, Chaintreuil C, Fardoux J, Nguyen P, Marchetti R, Nouwen N, Molinaro A, Mergaert P, Giraud E. A Peptidoglycan-Remodeling Enzyme Is Critical for Bacteroid Differentiation in Bradyrhizobium spp. During Legume Symbiosis. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:447-57. [PMID: 26959836 DOI: 10.1094/mpmi-03-16-0052-r] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In response to the presence of compatible rhizobium bacteria, legumes form symbiotic organs called nodules on their roots. These nodules house nitrogen-fixing bacteroids that are a differentiated form of the rhizobium bacteria. In some legumes, the bacteroid differentiation comprises a dramatic cell enlargement, polyploidization, and other morphological changes. Here, we demonstrate that a peptidoglycan-modifying enzyme in Bradyrhizobium strains, a DD-carboxypeptidase that contains a peptidoglycan-binding SPOR domain, is essential for normal bacteroid differentiation in Aeschynomene species. The corresponding mutants formed bacteroids that are malformed and hypertrophied. However, in soybean, a plant that does not induce morphological differentiation of its symbiont, the mutation does not affect the bacteroids. Remarkably, the mutation also leads to necrosis in a large fraction of the Aeschynomene nodules, indicating that a normally formed peptidoglycan layer is essential for avoiding the induction of plant immune responses by the invading bacteria. In addition to exopolysaccharides, capsular polysaccharides, and lipopolysaccharides, whose role during symbiosis is well defined, our work demonstrates an essential role in symbiosis for yet another rhizobial envelope component, the peptidoglycan layer.
Collapse
Affiliation(s)
- Djamel Gully
- 1 IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, 34398 Montpellier Cedex 5, France
| | | | - Katia Bonaldi
- 3 Center for Chronobiology, Division of Biological Sciences, 9500 Gilman Drive, University of California San Diego, La Jolla, CA 92093, U.S.A
| | - Cédric Grangeteau
- 4 UMR Procédés Alimentaires et Microbiologiques, Equipe VAlMiS (Vin, Aliment, Microbiologie, Stress), AgroSup Dijon - Université de Bourgogne Franche-Comté, IUVV, Rue Claude Ladrey, BP 27877, 21000 Dijon, France
| | - Clémence Chaintreuil
- 1 IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, 34398 Montpellier Cedex 5, France
| | - Joël Fardoux
- 1 IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, 34398 Montpellier Cedex 5, France
| | - Phuong Nguyen
- 1 IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, 34398 Montpellier Cedex 5, France
| | - Roberta Marchetti
- 5 Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Via Cintia 4, I-80126 Napoli, Italy; and
| | - Nico Nouwen
- 1 IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, 34398 Montpellier Cedex 5, France
| | - Antonio Molinaro
- 5 Dipartimento di Scienze Chimiche, Complesso Universitario Monte Sant'Angelo, Università di Napoli Federico II, Via Cintia 4, I-80126 Napoli, Italy; and
| | - Peter Mergaert
- 6 Institute for Integrative Biology of the Cell, UMR 9198, CNRS/Université Paris-Sud/CEA, Gif-sur-Yvette, France
| | - Eric Giraud
- 1 IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR IRD/SupAgro/INRA/UM2/CIRAD, Campus International de Baillarguet, TA A-82/J, 34398 Montpellier Cedex 5, France
| |
Collapse
|
34
|
A cell wall damage response mediated by a sensor kinase/response regulator pair enables beta-lactam tolerance. Proc Natl Acad Sci U S A 2015; 113:404-9. [PMID: 26712007 DOI: 10.1073/pnas.1520333113] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The bacterial cell wall is critical for maintenance of cell shape and survival. Following exposure to antibiotics that target enzymes required for cell wall synthesis, bacteria typically lyse. Although several cell envelope stress response systems have been well described, there is little knowledge of systems that modulate cell wall synthesis in response to cell wall damage, particularly in Gram-negative bacteria. Here we describe WigK/WigR, a histidine kinase/response regulator pair that enables Vibrio cholerae, the cholera pathogen, to survive exposure to antibiotics targeting cell wall synthesis in vitro and during infection. Unlike wild-type V. cholerae, mutants lacking wigR fail to recover following exposure to cell-wall-acting antibiotics, and they exhibit a drastically increased cell diameter in the absence of such antibiotics. Conversely, overexpression of wigR leads to cell slimming. Overexpression of activated WigR also results in increased expression of the full set of cell wall synthesis genes and to elevated cell wall content. WigKR-dependent expression of cell wall synthesis genes is induced by various cell-wall-acting antibiotics as well as by overexpression of an endogenous cell wall hydrolase. Thus, WigKR appears to monitor cell wall integrity and to enhance the capacity for increased cell wall production in response to damage. Taken together, these findings implicate WigKR as a regulator of cell wall synthesis that controls cell wall homeostasis in response to antibiotics and likely during normal growth as well.
Collapse
|
35
|
Abstract
E. coli is a relevant model organism for the study of the molecular mechanisms underlying surface colonization. This process requires two essential steps: adhesion to a surface, followed by cell-cell adhesion counteracting the shear forces of the environment, with both steps contributing to the formation of a biofilm. This review provides an overview of the current knowledge of the genetic analyses aiming at identifying factors involved in both of these two highly related biological processes, with a particular emphasis on studies performed in Escherichia coli K-12. Bacterial adhesion to abiotic surfaces is likely to be highly dependent on the physicochemical and electrostatic interactions between the bacterial envelope and the substrate, which is itself often conditioned by the fluids to which it is exposed. Genetic analyses have revealed the diversity of genetic factors in E. coli that participate in colonization and biofilm formation on abiotic surfaces. The study of surface colonization and biofilm formation represents a rapidly expanding field of investigation. The use of E. coli K-12 to investigate the genetic basis of bacterial interactions with surfaces has led to the identification of a large repertoire of adhesins whose expression is subject to a complex interplay between regulatory networks. Understanding how E. coli K-12 behaves in complex biofilm communities will certainly contribute to an understanding of how natural commensal and pathogenic E. coli isolates develop.
Collapse
|
36
|
Möll A, Dörr T, Alvarez L, Davis BM, Cava F, Waldor MK. A D, D-carboxypeptidase is required for Vibrio cholerae halotolerance. Environ Microbiol 2015; 17:527-40. [PMID: 25631756 DOI: 10.1111/1462-2920.12779] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/06/2015] [Accepted: 01/08/2015] [Indexed: 11/28/2022]
Abstract
The biological roles of low molecular weight penicillin-binding proteins (LMW PBP) have been difficult to discern in Gram-negative organisms. In Escherichia coli, mutants lacking these proteins often have no phenotype, and cells lacking all seven LMW PBPs remain viable. In contrast, we report here that Vibrio cholerae lacking DacA-1, a PBP5 homologue, displays slow growth, aberrant morphology and altered peptidoglycan (PG) homeostasis in Luria-Bertani (LB) medium, as well as a profound plating defect. DacA-1 alone among V. cholerae's LMW PBPs is critical for bacterial growth; mutants lacking the related protein DacA-2 and/or homologues of PBP4 or PBP7 displayed normal growth and morphology. Remarkably, the growth and morphology of the dacA-1 mutant were unimpaired in LB media containing reduced concentrations of NaCl (100 mM or less), and also within suckling mice, a model host for the study of cholera pathogenesis. Peptidoglycan from the dacA-1 mutant contained elevated pentapeptide levels in standard and low salt media, and comparative analyses suggest that DacA-1 is V. cholerae's principal DD-carboxypeptidase. The basis for the dacA-1 mutant's halosensitivity is unknown; nonetheless, the mutant's survival in biochemically uncharacterized environments (such as the suckling mouse intestine) can be used as a reporter of low Na(+) content.
Collapse
Affiliation(s)
- Andrea Möll
- Division of Infectious Diseases, Brigham and Women's Hospital, Boston, MA, 02155, USA; Department of Microbiology and Immunobiology, Harvard Medical School, HHMI, Boston, MA, 02155, USA
| | | | | | | | | | | |
Collapse
|
37
|
Abstract
Bacteria are extremely versatile organisms that rapidly adapt to changing environments. When bacterial cells switch from planktonic growth to biofilm, flagellum formation is turned off and the production of fimbriae and extracellular polysaccharides is switched on. BolA is present in most Gram-negative bacteria, and homologues can be found from proteobacteria to eukaryotes. Here, we show that BolA is a new bacterial transcription factor that modulates the switch from a planktonic to a sessile lifestyle. It negatively modulates flagellar biosynthesis and swimming capacity in Escherichia coli. Furthermore, BolA overexpression favors biofilm formation, involving the production of fimbria-like adhesins and curli. Our results also demonstrate that BolA is a protein with high affinity to DNA and is able to regulate many genes on a genome-wide scale. Moreover, we show that the most significant targets of this protein involve a complex network of genes encoding proteins related to biofilm development. Herein, we propose that BolA is a motile/adhesive transcriptional switch, specifically involved in the transition between the planktonic and the attachment stage of biofilm formation. Escherichia coli cells possess several mechanisms to cope with stresses. BolA has been described as a protein important for survival in late stages of bacterial growth and under harsh environmental conditions. BolA-like proteins are widely conserved from prokaryotes to eukaryotes. Although their exact function is not fully established at the molecular level, they seem to be involved in cell proliferation or cell cycle regulation. Here, we unraveled the role of BolA in biofilm development and bacterial motility. Our work suggests that BolA actively contributes to the decision of bacteria to arrest flagellar production and initiate the attachment to form structured communities, such as biofilms. The molecular studies of different lifestyles coupled with the comprehension of the BolA functions may be an important step for future perspectives, with health care and biotechnology applications.
Collapse
|
38
|
Wang D, Liang H, Chen J, Mou Y, Qi Y. Structural and Environmental Features of NovelMdfAVariant andMdfAGenes in Recombinant Regions ofEscherichia coli. Microb Drug Resist 2014; 20:392-8. [PMID: 24684286 DOI: 10.1089/mdr.2013.0201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Dongguo Wang
- Department of Clinical Lab Medicine, Taizhou University affiliated Taizhou Municipal Hospital, Taizhou, China
- Institute of Molecular Diagnostics of Taizhou University, Taizhou, China
| | - Haiyan Liang
- Department of Neurology, Taizhou University affiliated Taizhou Municipal Hospital, Taizhou, China
| | - Jiayu Chen
- Department of Lab Medicine, Medical College of Taizhou University, Taizhou, China
- Institute of Molecular Diagnostics of Taizhou University, Taizhou, China
| | - Yonghua Mou
- Department of Hepatobiliary Surgery, Taizhou Municipal Hospital of Taizhou University, Taizhou, China
| | - Yongxiao Qi
- Department of Lab Medicine, Medical College of Taizhou University, Taizhou, China
- Institute of Molecular Diagnostics of Taizhou University, Taizhou, China
| |
Collapse
|
39
|
Breaking through the stress barrier: the role of BolA in Gram-negative survival. World J Microbiol Biotechnol 2014; 30:2559-66. [PMID: 25038865 DOI: 10.1007/s11274-014-1702-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022]
Abstract
The morphogene bolA plays a significant role in the adaptation of Escherichia coli to general stresses. In general, bacteria can thrive and persist under harsh conditions, counteracting external stresses by using varied mechanisms, including biofilm formation, changes in cell shape, size and protein content, together with alterations in the cell wall structure, thickness and permeability. In E. coli, an increased expression of bolA occurs mainly under stress challenges and when bacterial morphology changes from rod-like to spherical. Moreover, BolA is able to induce biofilm formation and changes in the outer membrane, making it less permeable to harmful agents. Although there has been substantial progress in the description of BolA activity, its role on global cell physiology is still incomplete. Proteins with strong homology to BolA have been found in most living organisms, in many cases also exerting a regulatory role. In this review we summarize current knowledge on the role of BolA, mainly in E. coli, and discuss its implication in global regulation in relation to stress.
Collapse
|
40
|
Couturier J, Wu HC, Dhalleine T, Pégeot H, Sudre D, Gualberto JM, Jacquot JP, Gaymard F, Vignols F, Rouhier N. Monothiol glutaredoxin-BolA interactions: redox control of Arabidopsis thaliana BolA2 and SufE1. MOLECULAR PLANT 2014; 7:187-205. [PMID: 24203231 DOI: 10.1093/mp/sst156] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A functional relationship between monothiol glutaredoxins and BolAs has been unraveled by genomic analyses and in several high-throughput studies. Phylogenetic analyses coupled to transient expression of green fluorescent protein (GFP) fusions indicated that, in addition to the sulfurtransferase SufE1, which contains a C-terminal BolA domain, three BolA isoforms exist in Arabidopsis thaliana, BolA1 being plastidial, BolA2 nucleo-cytoplasmic, and BolA4 dual-targeted to mitochondria and plastids. Binary yeast two-hybrid experiments demonstrated that all BolAs and SufE1, via its BolA domain, can interact with all monothiol glutaredoxins. Most interactions between protein couples of the same subcellular compartment have been confirmed by bimolecular fluorescence complementation. In vitro experiments indicated that monothiol glutaredoxins could regulate the redox state of BolA2 and SufE1, both proteins possessing a single conserved reactive cysteine. Indeed, a glutathionylated form of SufE1 lost its capacity to activate the cysteine desulfurase, Nfs2, but it is reactivated by plastidial glutaredoxins. Besides, a monomeric glutathionylated form and a dimeric disulfide-bridged form of BolA2 can be preferentially reduced by the nucleo-cytoplasmic GrxS17. These results indicate that the glutaredoxin-BolA interaction occurs in several subcellular compartments and suggest that a redox regulation mechanism, disconnected from their capacity to form iron-sulfur cluster-bridged heterodimers, may be physiologically relevant for BolA2 and SufE1.
Collapse
Affiliation(s)
- Jérémy Couturier
- a Université de Lorraine, Interactions Arbres-Microorganismes, UMR1136, F-54500 Vandoeuvre-lès-Nancy, France
| | | | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Wang D, Hu E, Chen J, Tao X, Gutierrez K, Qi Y. Characterization of novel ybjG and dacC variants in Escherichia coli. J Med Microbiol 2013; 62:1728-1734. [PMID: 23912810 DOI: 10.1099/jmm.0.062893-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A total of 69 strains of Escherichia coli from patients in the Taizhou Municipal Hospital, China, were isolated, and 11 strains were identified that were resistant to bacitracin, chloramphenicol, tetracycline and erythromycin. These strains were PCR positive for at least two out of three genes, ybjG, dacC and mdfA, by gene mapping with conventional PCR detection. Conjugation experiments demonstrated that these genes existed in plasmids that conferred resistance. Novel ybjG and dacC variants were isolated from E. coli strains EC2163 and EC2347, which were obtained from the sputum of intensive care unit patients. Genetic mapping showed that the genes were located on 8200 kb plasmid regions flanked by EcoRI restriction sites. Three distinct genetic structures were identified among the 11 PCR-positive strains of E. coli, and two contained the novel ybjG and dacC variants. The putative amino acid differences in the ybjG and dacC gene variants were characterized. These results provide evidence for novel variants of ybjG and dacC, and suggest that multiple drug resistance in hospital strains of E. coli depends on the synergistic function of ybjG, dacC and mdfA within three distinct genetic structures in conjugative plasmids.
Collapse
Affiliation(s)
- Dongguo Wang
- Department of Clinical Lab Medicine, Taizhou University affiliated Taizhou Municipal Hospital, Taizhou, PR China
| | - Enping Hu
- Department of Urology Surgery, Taizhou University affiliated Taizhou Municipal Hospital, Taizhou, PR China
| | - Jiayu Chen
- Department of Lab Medicine, Medical College of Taizhou University, Taizhou, PR China
| | - Xiulin Tao
- Department of Urology Surgery, Taizhou University affiliated Taizhou Municipal Hospital, Taizhou, PR China
| | | | - Yongxiao Qi
- Department of Lab Medicine, Medical College of Taizhou University, Taizhou, PR China
| |
Collapse
|
42
|
Synthetic effect between envelope stress and lack of outer membrane vesicle production in Escherichia coli. J Bacteriol 2013; 195:4161-73. [PMID: 23852867 DOI: 10.1128/jb.02192-12] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Outer membrane vesicles (OMVs) are composed of outer membrane and periplasmic components and are ubiquitously secreted by Gram-negative bacteria. OMVs can disseminate virulence factors for pathogenic bacteria as well as serve as an envelope stress response. From a transposon mutant screen for OMV phenotypes, it was discovered that an nlpA mutant of Escherichia coli produces fewer OMVs than the wild type, whereas a degP mutant produces higher levels of OMVs. NlpA is an inner-membrane-anchored lipoprotein that has a minor role in methionine import. DegP is a periplasmic chaperone/protease for misfolded envelope proteins that is critical when cells are heat shocked. To reveal how these proteins contribute to OMV production, the mutations were combined and the double mutant analyzed. The ΔnlpA ΔdegP strain displayed a high-temperature growth defect that corresponded to the production of fewer OMVs than produced by the ΔdegP strain. This phenotype also pertained to other undervesiculation mutations in a ΔdegP background. The hypovesiculation phenotype of ΔnlpA in the wild-type strain as well as in the degP deletion strain was found to be a stationary-phase phenomenon. The periplasm of the ΔnlpA ΔdegP strain was determined to contain significantly more protein in stationary phase than the wild type. Additionally, misfolded DegP substrate outer membrane porins were detected in ΔdegP mutant-derived OMVs. These data suggest that an accumulation of envelope proteins resulting from decreased vesiculation was toxic and contributed to the growth defect. We conclude that OMV production contributes to relieve the envelope of accumulated toxic proteins and that NlpA plays an important role in the production of vesicles in stationary phase.
Collapse
|
43
|
Desmarais SM, De Pedro MA, Cava F, Huang KC. Peptidoglycan at its peaks: how chromatographic analyses can reveal bacterial cell wall structure and assembly. Mol Microbiol 2013; 89:1-13. [PMID: 23679048 DOI: 10.1111/mmi.12266] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2013] [Indexed: 02/02/2023]
Abstract
The peptidoglycan (PG) cell wall is a unique macromolecule responsible for both shape determination and cellular integrity under osmotic stress in virtually all bacteria. A quantitative understanding of the relationships between PG architecture, morphogenesis, immune system activation and pathogenesis can provide molecular-scale insights into the function of proteins involved in cell wall synthesis and cell growth. High-performance liquid chromatography (HPLC) has played an important role in our understanding of the structural and chemical complexity of the cell wall by providing an analytical method to quantify differences in chemical composition. Here, we present a primer on the basic chemical features of wall structure that can be revealed through HPLC, along with a description of the applications of HPLC PG analyses for interpreting the effects of genetic and chemical perturbations to a variety of bacterial species in different environments. We describe the physical consequences of different PG compositions on cell shape, and review complementary experimental and computational methodologies for PG analysis. Finally, we present a partial list of future targets of development for HPLC and related techniques.
Collapse
|
44
|
Jones TH, Vail KM, McMullen LM. Filament formation by foodborne bacteria under sublethal stress. Int J Food Microbiol 2013; 165:97-110. [PMID: 23727653 DOI: 10.1016/j.ijfoodmicro.2013.05.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 04/26/2013] [Accepted: 05/01/2013] [Indexed: 11/28/2022]
Abstract
A number of studies have reported that pathogenic and nonpathogenic foodborne bacteria have the ability to form filaments in microbiological growth media and foods after prolonged exposure to sublethal stress or marginal growth conditions. In many cases, nucleoids are evenly spaced throughout the filamentous cells but septa are not visible, indicating that there is a blockage in the early steps of cell division but the mechanism behind filament formation is not clear. The formation of filamentous cells appears to be a reversible stress response. When filamentous cells are exposed to more favorable growth conditions, filaments divide rapidly into a number of individual cells, which may have major health and regulatory implications for the food industry because the potential numbers of viable bacteria will be underestimated and may exceed tolerated levels in foods when filamentous cells that are subjected to sublethal stress conditions are enumerated. Evidence suggests that filament formation under a number of sublethal stresses may be linked to a reduced energy state of bacterial cells. This review focuses on the conditions and extent of filament formation by foodborne bacteria under conditions that are used to control the growth of microorganisms in foods such as suboptimal pH, high pressure, low water activity, low temperature, elevated CO2 and exposure to antimicrobial substances as well as lack a of nutrients in the food environment and explores the impact of the sublethal stresses on the cell's inability to divide.
Collapse
Affiliation(s)
- Tineke H Jones
- Agriculture and Agri-Food Canada, Lacombe Research Centre, 6000 C&E Trail, Lacombe, Alberta T4L 1W1, Canada.
| | | | | |
Collapse
|
45
|
Growth media simulating ileal and colonic environments affect the intracellular proteome and carbon fluxes of enterohemorrhagic Escherichia coli O157:H7 strain EDL933. Appl Environ Microbiol 2013; 79:3703-15. [PMID: 23563955 DOI: 10.1128/aem.00062-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this study, the intracellular proteome of Escherichia coli O157:H7 strain EDL933 was analyzed by two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) spectrometry after growth in simulated ileal environment media (SIEM) and simulated colonic environment media (SCEM) under aerobic and microaerobic conditions. Differentially expressed intracellular proteins were identified and allocated to functional protein groups. Moreover, metabolic fluxes were analyzed by isotopologue profiling with [U-(13)C(6)]glucose as a tracer. The results of this study show that EDL933 responds with differential expression of a complex network of proteins and metabolic pathways, reflecting the high metabolic adaptability of the strain. Growth in SIEM and SCEM is obviously facilitated by the upregulation of nucleotide biosynthesis pathway proteins and could be impaired by exposition to 50 µM 6-mercaptopurine under aerobic conditions. Notably, various stress and virulence factors, including Shiga toxin, were expressed without having contact with a human host.
Collapse
|
46
|
Boutigny S, Saini A, Baidoo EEK, Yeung N, Keasling JD, Butland G. Physical and functional interactions of a monothiol glutaredoxin and an iron sulfur cluster carrier protein with the sulfur-donating radical S-adenosyl-L-methionine enzyme MiaB. J Biol Chem 2013; 288:14200-14211. [PMID: 23543739 DOI: 10.1074/jbc.m113.460360] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The biosynthesis of iron sulfur (FeS) clusters, their trafficking from initial assembly on scaffold proteins via carrier proteins to final incorporation into FeS apoproteins, is a highly coordinated process enabled by multiprotein systems encoded in iscRSUAhscBAfdx and sufABCDSE operons in Escherichia coli. Although these systems are believed to encode all factors required for initial cluster assembly and transfer to FeS carrier proteins, accessory factors such as monothiol glutaredoxin, GrxD, and the FeS carrier protein NfuA are located outside of these defined systems. These factors have been suggested to function both as shuttle proteins acting to transfer clusters between scaffold and carrier proteins and in the final stages of FeS protein assembly by transferring clusters to client FeS apoproteins. Here we implicate both of these factors in client protein interactions. We demonstrate specific interactions between GrxD, NfuA, and the methylthiolase MiaB, a radical S-adenosyl-L-methionine-dependent enzyme involved in the maturation of a subset of tRNAs. We show that GrxD and NfuA physically interact with MiaB with affinities compatible with an in vivo function. We furthermore demonstrate that NfuA is able to transfer its cluster in vitro to MiaB, whereas GrxD is unable to do so. The relevance of these interactions was demonstrated by linking the activity of MiaB with GrxD and NfuA in vivo. We observe a severe defect in in vivo MiaB activity in cells lacking both GrxD and NfuA, suggesting that these proteins could play complementary roles in maturation and repair of MiaB.
Collapse
Affiliation(s)
- Sylvain Boutigny
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Avneesh Saini
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Edward E K Baidoo
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; Joint BioEnergy Institute, Emeryville, California 94608
| | - Natasha Yeung
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Jay D Keasling
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720; Joint BioEnergy Institute, Emeryville, California 94608; Department of Chemical Engineering, University of California, Berkeley, California 94720; Department of Bioengineering, University of California, Berkeley, California 94720
| | - Gareth Butland
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
| |
Collapse
|
47
|
Expression of blaA underlies unexpected ampicillin-induced cell lysis of Shewanella oneidensis. PLoS One 2013; 8:e60460. [PMID: 23555975 PMCID: PMC3610667 DOI: 10.1371/journal.pone.0060460] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 02/26/2013] [Indexed: 02/05/2023] Open
Abstract
Shewanella oneidensis is a facultative anaerobic γ-proteobacterium possessing remarkably diverse respiratory capacities for reducing various organic and inorganic substrates. As a veteran research model for investigating redox transformations of environmental contaminants the bacterium is well known to be a naturally ampicillin-resistant microorganism. However, in this study we discovered that ampicillin has a significant impact on growth of S. oneidensis. Particularly, cell lysis occurred only with ampicillin at levels ranging from 0.49 to 6.25 µg/ml but not at 50 µg/ml. This phenotype is attributable to insufficient expression of the β-lactamase BlaA. The subsequent analysis revealed that the blaA gene is strongly induced by ampicillin at high (50 µg/ml), but not at low levels (2.5 µg/ml). In addition, we demonstrated that penicillin binding protein 5 (PBP5), the most abundant low molecular weight PBP (LMW PBP), is the only one relevant to β-lactam resistance under the tested conditions. This nonessential PBP, largely resembling its Escherichia coli counterpart in functionality, mediates expression of the blaA gene.
Collapse
|
48
|
Brinza L, Calevro F, Charles H. Genomic analysis of the regulatory elements and links with intrinsic DNA structural properties in the shrunken genome of Buchnera. BMC Genomics 2013; 14:73. [PMID: 23375088 PMCID: PMC3571970 DOI: 10.1186/1471-2164-14-73] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Accepted: 01/23/2013] [Indexed: 01/19/2023] Open
Abstract
Background Buchnera aphidicola is an obligate symbiotic bacterium, associated with most of the aphididae, whose genome has drastically shrunk during intracellular evolution. Gene regulation in Buchnera has been a matter of controversy in recent years as the combination of genomic information with the experimental results has been contradictory, refuting or arguing in favour of a functional and responsive transcription regulation in Buchnera. The goal of this study was to describe the gene transcription regulation capabilities of Buchnera based on the inventory of cis- and trans-regulators encoded in the genomes of five strains from different aphids (Acyrthosiphon pisum, Schizaphis graminum, Baizongia pistacea, Cinara cedri and Cinara tujafilina), as well as on the characterisation of some intrinsic structural properties of the DNA molecule in these bacteria. Results Interaction graph analysis shows that gene neighbourhoods are conserved between E. coli and Buchnera in structures called transcriptons, interactons and metabolons, indicating that selective pressures have acted on the evolution of transcriptional, protein-protein interaction and metabolic networks in Buchnera. The transcriptional regulatory network in Buchnera is composed of a few general DNA-topological regulators (Nucleoid Associated Proteins and topoisomerases), with the quasi-absence of any specific ones (except for multifunctional enzymes with a known gene expression regulatory role in Escherichia coli, such as AlaS, PepA and BolA, and the uncharacterized hypothetical regulators YchA and YrbA). The relative positioning of regulatory genes along the chromosome of Buchnera seems to have conserved its ancestral state, despite the genome erosion. Sigma-70 promoters with canonical thermodynamic sequence profiles were detected upstream of about 94% of the CDS of Buchnera in the different aphids. Based on Stress-Induced Duplex Destabilization (SIDD) measurements, unstable σ70 promoters were found specifically associated with the regulator and transporter genes. Conclusions This genomic analysis provides supporting evidence of a selection of functional regulatory structures and it has enabled us to propose hypotheses concerning possible links between these regulatory elements and the DNA-topology (i.e., supercoiling, curvature, flexibility and base-pair stability) in the regulation of gene expression in the shrunken genome of Buchnera.
Collapse
Affiliation(s)
- Lilia Brinza
- UMR203 BF2I, Biologie Fonctionnelle Insectes et Interactions, INSA-Lyon, INRA, Université de Lyon, Villeurbanne, France
| | | | | |
Collapse
|
49
|
Willems P, Wanschers BFJ, Esseling J, Szklarczyk R, Kudla U, Duarte I, Forkink M, Nooteboom M, Swarts H, Gloerich J, Nijtmans L, Koopman W, Huynen MA. BOLA1 is an aerobic protein that prevents mitochondrial morphology changes induced by glutathione depletion. Antioxid Redox Signal 2013; 18:129-38. [PMID: 22746225 PMCID: PMC3513987 DOI: 10.1089/ars.2011.4253] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
AIMS The BolA protein family is widespread among eukaryotes and bacteria. In Escherichia coli, BolA causes a spherical cell shape and is overexpressed during oxidative stress. Here we aim to elucidate the possible role of its human homolog BOLA1 in mitochondrial morphology and thiol redox potential regulation. RESULTS We show that BOLA1 is a mitochondrial protein that counterbalances the effect of L-buthionine-(S,R)-sulfoximine (BSO)-induced glutathione (GSH) depletion on the mitochondrial thiol redox potential. Furthermore, overexpression of BOLA1 nullifies the effect of BSO and S-nitrosocysteine on mitochondrial morphology. Conversely, knockdown of the BOLA1 gene increases the oxidation of mitochondrial thiol groups. Supporting a role of BOLA1 in controlling the mitochondrial thiol redox potential is that BOLA1 orthologs only occur in aerobic eukaryotes. A measured interaction of BOLA1 with the mitochondrial monothiol glutaredoxin GLRX5 provides hints for potential mechanisms behind BOLA1's effect on mitochondrial redox potential. Nevertheless, we have no direct evidence for a role of GLRX5 in BOLA1's function. INNOVATION We implicate a new protein, BOLA1, in the regulation of the mitochondrial thiol redox potential. CONCLUSION BOLA1 is an aerobic, mitochondrial protein that prevents mitochondrial morphology aberrations induced by GSH depletion and reduces the associated oxidative shift of the mitochondrial thiol redox potential.
Collapse
Affiliation(s)
- Peter Willems
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
50
|
|