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Burmeister AR, Tewatia H, Skinner C. A tradeoff between bacteriophage resistance and bacterial motility is mediated by the Rcs phosphorelay in Escherichia coli. MICROBIOLOGY (READING, ENGLAND) 2024; 170. [PMID: 39194382 DOI: 10.1099/mic.0.001491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/29/2024]
Abstract
Across the tree of life, pleiotropy is thought to constrain adaptation through evolutionary tradeoffs. However, few examples of pleiotropy exist that are well explained at the genetic level, especially for pleiotropy that is mediated by multiple genes. Here, we describe a set of pleiotropic mutations that mediate two key fitness components in bacteria: parasite resistance and motility. We subjected Escherichia coli to strong selection by phage U136B to obtain 27 independent mucoid mutants. Mucoidy is a phenotype that results from excess exopolysaccharide and can act as a barrier against viral infection but can also interfere with other cellular functions. We quantified the mutants' phage resistance using efficiency of plaquing assays and swimming motility using swim agar plates, and we sequenced the complete genomes of all mutants to identify mucoid-causing mutations. Increased phage resistance co-occurred with decreased motility. This relationship was mediated by highly parallel (27/27) mutations to the Rcs phosphorelay pathway, which senses membrane stress to regulate exopolysaccharide production. Together, these results provide an empirical example of a pleiotropic relationship between two traits with intermediate genetic complexity.
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Affiliation(s)
- Alita R Burmeister
- Department of Biological Sciences, University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - Harleen Tewatia
- Department of Biological Sciences, University of Wisconsin Milwaukee, Milwaukee, WI, USA
| | - Chloé Skinner
- Department of Biological Sciences, University of Wisconsin Milwaukee, Milwaukee, WI, USA
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2
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Ma Z, Sun Y, Liu Y, Jiao J, Li N, Zuo Y, Li Z, Li Y, Cai X, Meng Q, Qiao J. STM1863, a Member of the DUFs Protein Family, Is Involved in Environmental Adaptation, Biofilm Formation, and Virulence in Salmonella Typhimurium. Foodborne Pathog Dis 2024. [PMID: 38625018 DOI: 10.1089/fpd.2023.0139] [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: 04/17/2024] Open
Abstract
Salmonella Typhimurium (STM) is an important zoonotic Gram-negative pathogen that can cause infection in a variety of livestock and poultry. Meanwhile, as an important foodborne pathogen, the bacterium can survive in various stressful environments and transmits through the fecal-oral route, posing a serious threat to global food safety. To investigate the roles of STM1863, a member of the DUFs protein family, involved in STM environmental adaptation, biofilm formation, and virulence. We analyzed the molecular characteristics of the protein encoded by STM1863 gene and examined intra- and extracellular expression levels of STM1863 gene in mouse macrophages. Furthermore, we constructed STM1863 gene deletion and complementation strains and determined its environmental adaptation under stressful conditions such as acid, alkali, high salt, bile salt, and oxidation. And the capacity of biofilm formation and pathogenicity of those strains were analyzed and compared. In addition, the interaction between the promoter of STM1863 gene and RcsB protein was analyzed using DNA gel electrophoresis migration assay (electrophoretic mobility shift assay [EMSA]). The experiments revealed that acid adaptability and biofilm formation ability of STM1863 gene deletion strain were significantly weakened compared with the parental and complementary strains. Moreover, the adhesion and invasion ability of STM1863 deletion strain to mouse macrophages was significantly decreased, while the median lethal dose (LD50) increased by 2.148-fold compared with the parental strain. In addition, EMSA confirmed that RcsB protein could bind to the promoter sequence of STM1863 gene, suggesting that the expression of STM1863 gene might be modulated by RcsB. The present study demonstrated for the first time that STM1863, a member of the DUFs protein family, is involved in the modulation of environmental adaptation, biofilm formation, and virulence.
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Affiliation(s)
- Zhongmei Ma
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Yaoqiang Sun
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Yuchen Liu
- State Key Laboratory for Sheep Genetic Improvement and Healthy Production, Xinjiang Academy of Agricultural and Reclamation Science, Shihezi, Xinjiang, China
| | - Jian Jiao
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Nengxiu Li
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Yufei Zuo
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Zhiyuan Li
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Yaling Li
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Xuepeng Cai
- State Key Lab of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
| | - Qingling Meng
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
| | - Jun Qiao
- College of Animal Science and Technology, Shihezi University, Shihezi, Xinjiang, China
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Pokorzynski ND, Groisman EA. How Bacterial Pathogens Coordinate Appetite with Virulence. Microbiol Mol Biol Rev 2023; 87:e0019822. [PMID: 37358444 PMCID: PMC10521370 DOI: 10.1128/mmbr.00198-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2023] Open
Abstract
Cells adjust growth and metabolism to nutrient availability. Having access to a variety of carbon sources during infection of their animal hosts, facultative intracellular pathogens must efficiently prioritize carbon utilization. Here, we discuss how carbon source controls bacterial virulence, with an emphasis on Salmonella enterica serovar Typhimurium, which causes gastroenteritis in immunocompetent humans and a typhoid-like disease in mice, and propose that virulence factors can regulate carbon source prioritization by modifying cellular physiology. On the one hand, bacterial regulators of carbon metabolism control virulence programs, indicating that pathogenic traits appear in response to carbon source availability. On the other hand, signals controlling virulence regulators may impact carbon source utilization, suggesting that stimuli that bacterial pathogens experience within the host can directly impinge on carbon source prioritization. In addition, pathogen-triggered intestinal inflammation can disrupt the gut microbiota and thus the availability of carbon sources. By coordinating virulence factors with carbon utilization determinants, pathogens adopt metabolic pathways that may not be the most energy efficient because such pathways promote resistance to antimicrobial agents and also because host-imposed deprivation of specific nutrients may hinder the operation of certain pathways. We propose that metabolic prioritization by bacteria underlies the pathogenic outcome of an infection.
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Affiliation(s)
- Nick D. Pokorzynski
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
| | - Eduardo A. Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut, USA
- Yale Microbial Sciences Institute, West Haven, Connecticut, USA
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4
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Guo XP, Yan HQ, Yang W, Yin Z, Vadyvaloo V, Zhou D, Sun YC. A frameshift in Yersinia pestis rcsD alters canonical Rcs signalling to preserve flea-mammal plague transmission cycles. eLife 2023; 12:e83946. [PMID: 37010269 PMCID: PMC10191623 DOI: 10.7554/elife.83946] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 04/02/2023] [Indexed: 04/04/2023] Open
Abstract
Multiple genetic changes in the enteric pathogen Yersinia pseudotuberculosis have driven the emergence of Yesinia pestis, the arthropod-borne, etiological agent of plague. These include developing the capacity for biofilm-dependent blockage of the flea foregut to enable transmission by flea bite. Previously, we showed that pseudogenization of rcsA, encoding a component of the Rcs signalling pathway, is an important evolutionary step facilitating Y. pestis flea-borne transmission. Additionally, rcsD, another important gene in the Rcs system, harbours a frameshift mutation. Here, we demonstrated that this rcsD mutation resulted in production of a small protein composing the C-terminal RcsD histidine-phosphotransferase domain (designated RcsD-Hpt) and full-length RcsD. Genetic analysis revealed that the rcsD frameshift mutation followed the emergence of rcsA pseudogenization. It further altered the canonical Rcs phosphorylation signal cascade, fine-tuning biofilm production to be conducive with retention of the pgm locus in modern lineages of Y. pestis. Taken together, our findings suggest that a frameshift mutation in rcsD is an important evolutionary step that fine-tuned biofilm production to ensure perpetuation of flea-mammal plague transmission cycles.
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Affiliation(s)
- Xiao-Peng Guo
- NHC key laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina
| | - Hai-Qin Yan
- Department of Basic Medical Sciences, Anhui Key Laboratory of Infection and Immunity, Bengbu Medical CollegeBengbuChina
- Paul G. Allen School for Global Health, Washington State UniversityPullmanUnited States
| | - Wenhui Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and EpidemiologyBeijingChina
| | - Zhe Yin
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and EpidemiologyBeijingChina
| | - Viveka Vadyvaloo
- Paul G. Allen School for Global Health, Washington State UniversityPullmanUnited States
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and EpidemiologyBeijingChina
| | - Yi-Cheng Sun
- NHC key laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical CollegeBeijingChina
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Harshaw NS, Meyer MD, Stella NA, Lehner KM, Kowalski RP, Shanks RMQ. The Short-chain Fatty Acid Propionic Acid Activates the Rcs Stress Response System Partially through Inhibition of d-Alanine Racemase. mSphere 2023; 8:e0043922. [PMID: 36645277 PMCID: PMC9942566 DOI: 10.1128/msphere.00439-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 12/16/2022] [Indexed: 01/17/2023] Open
Abstract
The Enterobacterial Rcs stress response system reacts to envelope stresses through a complex two-component phosphorelay system to regulate a variety of environmental response genes, such as capsular polysaccharide and flagella biosynthesis genes. However, beyond Escherichia coli, the stresses that activate Rcs are not well-understood. In this study, we used a Rcs system-dependent luminescent transcriptional reporter to screen a library of over 240 antimicrobial compounds for those that activated the Rcs system in Serratia marcescens, a Yersiniaceae family bacterium. Using an isogenic rcsB mutant to establish specificity, both new and expected activators were identified, including the short-chain fatty acid propionic acid, which is found at millimolar levels in the human gut. Propionic acid did not reduce the bacterial intracellular pH, as was hypothesized for its antibacterial mechanism. Instead, data suggest that the Rcs-activation by propionic acid is due, in part, to an inactivation of alanine racemase. This enzyme is responsible for the biosynthesis of d-alanine, which is an amino-acid that is required for the generation of bacterial cell walls. Consistent with what was observed in S. marcescens, in E. coli, alanine racemase mutants demonstrated elevated expression of the Rcs-reporter in a d-alanine-dependent and RcsB-dependent manner. These results suggest that host gut short-chain fatty acids can influence bacterial behavior via the activation of the Rcs stress response system. IMPORTANCE The Rcs bacterial stress response system responds to envelope stresses by globally altering gene expression to profoundly impact host-pathogen interactions, virulence, and antibiotic tolerance. In this study, a luminescent Rcs-reporter plasmid was used to screen a library of compounds for activators of Rcs. Among the strongest inducers was the short-chain fatty acid propionic acid, which is found at high concentrations in the human gut. This study suggests that gut short-chain fatty acids can affect both bacterial virulence and antibiotic tolerance via the induction of the Rcs system.
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Affiliation(s)
- Nathaniel S. Harshaw
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Mitchell D. Meyer
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Nicholas A. Stella
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Kara M. Lehner
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Regis P. Kowalski
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Robert M. Q. Shanks
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Kamemoto Y, Hikage R, Han Y, Sekiya Y, Sawasato K, Nishiyama KI. Coordinated upregulation of two CDP-diacylglycerol synthases, YnbB and CdsA, is essential for cell growth and membrane protein export in the cold. FEMS Microbiol Lett 2023; 370:fnad131. [PMID: 38070879 DOI: 10.1093/femsle/fnad131] [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: 10/19/2023] [Revised: 12/04/2023] [Accepted: 12/08/2023] [Indexed: 12/29/2023] Open
Abstract
YnbB is a paralogue of CdsA, a CDP-diacylglycerol synthase. While the cdsA gene is essential, the ynbB gene is dispensable. So far, no phenotype of ynbB knockout has been observed. We found that a ynbB knockout strain acquired cold-sensitivity on growth under CdsA-limited conditions. We found that MPIase, a glycolipid involved in protein export, is cold-upregulated to facilitate protein export in the cold, by increasing the mRNA levels of not only CdsA but also that of YnbB. Under non-permissive conditions, phospholipid biosynthesis proceeded normally, however, MPIase upregulation was inhibited with accumulation of precursors of membrane and secretory proteins such as M13 procoat and proOmpA, indicating that YnbB is dedicated to MPIase biosynthesis, complementing the CdsA function.
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Affiliation(s)
- Yuki Kamemoto
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Runa Hikage
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Youjung Han
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Yusei Sekiya
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Katsuhiro Sawasato
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
| | - Ken-Ichi Nishiyama
- The United Graduate School of Agricultural Sciences, Iwate University, Morioka, Iwate 020-8550, Japan
- Department of Applied Biological Chemistry and Food Sciences, Faculty of Agriculture, Iwate University, Morioka, Iwate 020-8550, Japan
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7
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Bian Z, Liu W, Jin J, Hao Y, Jiang L, Xie Y, Zhang H. Rcs phosphorelay affects the sensitivity of Escherichia coli to plantaricin BM-1 by regulating biofilm formation. Front Microbiol 2022; 13:1071351. [PMID: 36504793 PMCID: PMC9729257 DOI: 10.3389/fmicb.2022.1071351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 11/10/2022] [Indexed: 11/27/2022] Open
Abstract
Introduction: Plantaricin BM-1 is a class IIa bacteriocin produced by Lactobacillus plantarum BM-1 that exerts significant antibacterial activity against many foodborne bacteria. Studies have shown that class IIa bacteriocins inhibit Gram-positive bacteria via the mannose phosphotransferase system; however, their mechanism of action against Gram-negative bacteria remains unknown. In this study, we explored the mechanism through which the Rcs phosphorelay affects the sensitivity of Escherichia coli K12 cells to plantaricin BM-1. Methods and Results: The minimum inhibitory concentrations of plantaricin BM-1 against E. coli K12, E. coli JW5917 (rcsC mutant), E. coli JW2204 (rcsD mutant), and E. coli JW2205 (rcsB mutant) were 1.25, 0.59, 1.31, and 1.22 mg/ml, respectively. Growth curves showed that E. coli JW5917 sensitivity to plantaricin BM-1 increased to the same level as that of E. coli K12 after complementation. Meanwhile, scanning electron microscopy and transmission electron microscopy revealed that, under the action of plantaricin BM-1, the appearance of E. coli JW5917 cells did not significantly differ from that of E. coli K12 cells; however, cell contents were significantly reduced and plasmolysis and shrinkage were observed at both ends. Crystal violet staining and laser scanning confocal microscopy showed that biofilm formation was significantly reduced after rcsC mutation, while proteomic analysis identified 382 upregulated and 260 downregulated proteins in E. coli JW5917. In particular, rcsC mutation was found to affect the expression of proteins related to biofilm formation, with growth curve assays showing that the deletion of these proteins increased E. coli sensitivity to plantaricin BM-1. Discussion: Consequently, we speculated that the Rcs phosphorelay may regulate the sensitivity of E. coli to plantaricin BM-1 by affecting biofilm formation. This finding of class IIa bacteriocin against Gram-negative bacteria mechanism provides new insights.
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Affiliation(s)
- Zheng Bian
- Beijing Laboratory of Food Quality and Safety, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Engineering Technology Research Center of Food Safety Immune Rapid Detection, College of Food Science and Engineering, Beijing University of Agriculture, Beijing, China
| | - Wenbo Liu
- Beijing Laboratory of Food Quality and Safety, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Engineering Technology Research Center of Food Safety Immune Rapid Detection, College of Food Science and Engineering, Beijing University of Agriculture, Beijing, China
| | - Junhua Jin
- Beijing Laboratory of Food Quality and Safety, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Engineering Technology Research Center of Food Safety Immune Rapid Detection, College of Food Science and Engineering, Beijing University of Agriculture, Beijing, China
| | - Yanling Hao
- Department of Nutrition and Health, Key Laboratory of Functional Dairy, Co-constructed by Ministry of Education and Beijing Government, China Agricultural University, Beijing, China
| | - Linshu Jiang
- Animal Science and Technology College, Beijing University of Agriculture, Beijing, China
| | - Yuanhong Xie
- Beijing Laboratory of Food Quality and Safety, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Engineering Technology Research Center of Food Safety Immune Rapid Detection, College of Food Science and Engineering, Beijing University of Agriculture, Beijing, China,*Correspondence: Yuanhong Xie, ; Hongxing Zhang,
| | - Hongxing Zhang
- Beijing Laboratory of Food Quality and Safety, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Engineering Technology Research Center of Food Safety Immune Rapid Detection, College of Food Science and Engineering, Beijing University of Agriculture, Beijing, China,*Correspondence: Yuanhong Xie, ; Hongxing Zhang,
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8
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Stella NA, Romanowski EG, Brothers KM, Calvario RC, Shanks RMQ. IgaA Protein, GumB, Has a Global Impact on the Transcriptome and Surface Proteome of Serratia marcescens. Infect Immun 2022; 90:e0039922. [PMID: 36317876 PMCID: PMC9671016 DOI: 10.1128/iai.00399-22] [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] [Received: 09/07/2022] [Accepted: 09/30/2022] [Indexed: 11/07/2022] Open
Abstract
Bacterial stress response signaling systems, like the Rcs system are triggered by membrane and cell wall damaging compounds, including antibiotics and immune system factors. These regulatory systems help bacteria survive envelope stress by altering the transcriptome resulting in protective phenotypic changes that may also influence the virulence of the bacterium. This study investigated the role of the Rcs stress response system using a clinical keratitis isolate of Serratia marcescens with a mutation in the gumB gene. GumB, an IgaA ortholog, inhibits activation of the Rcs system, such that mutants have overactive Rcs signaling. Transcriptomic analysis indicated that approximately 15% of all S. marcescens genes were significantly altered with 2-fold or greater changes in expression in the ΔgumB mutant compared to the wild type, indicating a global transcriptional regulatory role for GumB. We further investigated the phenotypic consequences of two classes of genes with altered expression in the ΔgumB mutant expected to contribute to infections: serralysin metalloproteases PrtS, SlpB, and SlpE, and type I pili coded by fimABCD. Secreted fractions from the ΔgumB mutant had reduced cytotoxicity to a corneal cell line, and could be complemented by induced expression of prtS, but not cytolysin shlBA, phospholipase phlAB, or flagellar master regulator flhDC operons. Proteomic analysis, qRT-PCR, and type I pili-dependent yeast agglutination indicated an inhibitory role for the Rcs system in adhesin production. Together these data demonstrate GumB has a global impact on S. marcescens gene expression that had measurable effects on bacterial cytotoxicity and surface adhesin production.
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Affiliation(s)
- Nicholas A. Stella
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh Pennsylvania, USA
| | - Eric G. Romanowski
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh Pennsylvania, USA
| | - Kimberly M. Brothers
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh Pennsylvania, USA
| | - Rachel C. Calvario
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh Pennsylvania, USA
| | - Robert M. Q. Shanks
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh Pennsylvania, USA
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The Roles of the Two-Component System, MtrAB, in Response to Diverse Cell Envelope Stresses in Dietzia sp. DQ12-45-1b. Appl Environ Microbiol 2022; 88:e0133722. [PMID: 36190258 PMCID: PMC9599347 DOI: 10.1128/aem.01337-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Two-component systems (TCSs) act as common regulatory systems allowing bacteria to detect and respond to multiple environmental stimuli, including cell envelope stress. The MtrAB TCS of Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance, and thus is found to be highly conserved across this phylum. However, how precisely the MtrAB TCS regulates cellular homeostasis in response to environmental stress remains unclear. Here, we show that the MtrAB TCS plays an important role in the tolerance to different types of cell envelope stresses, including environmental stresses (i.e., oxidative stress, lysozyme, SDS, osmotic pressure, and alkaline pH stresses) and envelope-targeting antibiotics (i.e., isoniazid, ethambutol, glycopeptide, and β-lactam antibiotics) in Dietzia sp. DQ12-45-1b. An mtrAB mutant strain exhibited slower growth compared to the wild-type strain and was characterized by abnormal cell shapes when exposed to various environmental stresses. Moreover, deletion of mtrAB resulted in decreased resistance to isoniazid, ethambutol, and β-lactam antibiotics. Further, Cleavage under targets and tagmentation sequencing (CUT&Tag-seq) and electrophoretic mobility shift assays (EMSAs) revealed that MtrA binds the promoters of genes involved in peptidoglycan biosynthesis (ldtB, ldtA, murJ), hydrolysis (GJR88_03483, GJR88_4713), and cell division (ftsE). Together, our findings demonstrated that the MtrAB TCS is essential for the survival of Dietzia sp. DQ12-45-1b under various cell envelope stresses, primarily by controlling multiple downstream cellular pathways. Our work suggests that TCSs act as global sensors and regulators in maintaining cellular homeostasis, such as during episodes of various environmental stresses. The present study should shed light on the understanding of mechanisms for bacterial adaptivity to extreme environments. IMPORTANCE The multilayered cell envelope is the first line of bacterial defense against various extreme environments. Bacteria utilize a large number of sensing and regulatory systems to maintain cell envelope homeostasis under multiple stress conditions. The two-component system (TCS) is the main sensing and responding apparatus for environmental adaptation. The MtrAB TCS highly conserved in Actinobacteria is critical for cell wall homeostasis, cell proliferation, osmoprotection, and antibiotic resistance. However, how MtrAB works with regard to signals impacting changes to the cell envelope is not fully understood. Here, we found that in the Actinobacterium Dietzia sp. DQ12-45-1b, a TCS named MtrAB is pivotal for ensuring normal cell growth as well as maintaining proper cell morphology in response to various cell envelope stresses, namely, by regulating the expression of cell envelope-related genes. Our findings should greatly advance our understanding of the adaptive mechanisms responsible for maintaining cell integrity in times of sustained environmental shocks.
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Liu Y, Zhu S, Wei L, Feng Y, Cai L, Dunn S, McNally A, Zong Z. Arm race among closely-related carbapenem-resistant Klebsiella pneumoniae clones. ISME COMMUNICATIONS 2022; 2:76. [PMID: 37938732 PMCID: PMC9723571 DOI: 10.1038/s43705-022-00163-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 08/03/2022] [Accepted: 08/10/2022] [Indexed: 11/09/2023]
Abstract
Multiple carbapenem-resistant Klebsiella pneumoniae (CRKP) clones typically co-exist in hospital wards, but often certain clones will dominate. The factors driving this dominance are largely unclear. This study began from a genomic epidemiology analysis and followed by multiple approaches to identify the potential mechanisms driving the successful spread of a dominant clone. 638 patients in a 50-bed ICU were screened. 171 (26.8%) and 21 had CRKP from swabs and clinical specimens, respectively. Many (39.8% of those with ≥7-day ICU stay) acquired CRKP. After removing 18 unable to recover, 174 CRKP isolates were genome sequenced and belonged to six sequence types, with ST11 being the most prevalent (n = 154, 88.5%) and most (n = 169, 97.1%) carrying blaKPC-2. The 154 ST11 isolates belonged to 7 clones, with one (clone 1, KL64 capsular type) being dominant (n = 130, 84.4%). Clone 1 and the second-most common clone (clone 2, KL64, n = 15, 9.7%) emerged simultaneously, which was also detected by genome-based dating. Clone 1 exhibited decreased biofilm formation, shorter environment survival, and attenuated virulence. In murine gut, clone 1 outcompeted clone 2. Transcriptomic analysis showed significant upregulation of the ethanolamine operon in clone 1 when competing with clone 2. Clone 1 exhibited increased utilization of ethanolamine as a nitrogen source. This highlights that reduced virulence and enhanced ability to utilize ethanolamine may promote the success of nosocomial multidrug-resistant clones.
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Affiliation(s)
- Ying Liu
- Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China
- Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, China
| | - Shichao Zhu
- Department of Infection Control, West China Hospital, Sichuan University, Chengdu, China
| | - Li Wei
- Department of Infection Control, West China Hospital, Sichuan University, Chengdu, China
| | - Yu Feng
- Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China
- Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, China
| | - Lin Cai
- Intensive Care Unit, West China Hospital, Sichuan University, Chengdu, China
| | - Steven Dunn
- Institute of Microbiology and Infection, College of Medical and Dental Science, University of Birmingham, Birmingham, UK
| | - Alan McNally
- Institute of Microbiology and Infection, College of Medical and Dental Science, University of Birmingham, Birmingham, UK
| | - Zhiyong Zong
- Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China.
- Center for Pathogen Research, West China Hospital, Sichuan University, Chengdu, China.
- Department of Infection Control, West China Hospital, Sichuan University, Chengdu, China.
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11
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Elken EM, Tan ZN, Wang Q, Jiang XY, Wang Y, Wang YM, Ma HX. Impact of Sub-MIC Eugenol on Klebsiella pneumoniae Biofilm Formation via Upregulation of rcsB. Front Vet Sci 2022; 9:945491. [PMID: 35903134 PMCID: PMC9315372 DOI: 10.3389/fvets.2022.945491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
The Rcs phosphorelay system is present in many members of the Enterobacteriaceae. The aim of this study was to illustrate the possible mechanisms of eugenol on ultimate targets of Klebsiella pneumoniae (K. pneumoniae) Rcs phosphorelay, rcsB, and impact on biofilm formation. The minimum inhibitory concentration (MIC) of eugenol against K. pneumoniae KP1 and KP1 ΔrcsB strain was determined using the 2-fold micro-dilution method. Biofilm was measured by crystal violet staining. Transcriptome sequencing was performed to investigate sub-MIC eugenol on K. pneumoniae, and gene expression at mRNA level was analyzed by RT-qPCR. In vitro biofilm formation test and molecular docking were used to evaluate the effect of eugenol and to predict potential interactions with RcsB. MicroScale Thermophoresis (MST) was conducted for further validation. MIC of eugenol against K. pneumoniae KP1 and KP1 ΔrcsB strain was both 200 μg/ml. Transcriptome sequencing and RT-qPCR results indicated that rpmg, degP, rnpA, and dapD were downregulated, while rcsB, rcsD, rcsA, yiaG, and yiaD were upregulated in the eugenol-treated group. ΔrcsB exhibited a weakened biofilm formation capacity. Additional isopropyl-β-d-thiogalactoside (IPTG) hinders biofilm formation, while sub-MIC eugenol could promote biofilm formation greatly. Docking analysis revealed that eugenol forms more hydrophobic bonds than hydrogen bonds. MST assay also showed a weak binding affinity between eugenol and RcsB. These results provide significant evidence that rcsB plays a key role in K. pneumoniae biofilm formation. Sub-MIC eugenol facilitates biofilm formation to a large extent instead of inhibiting it. Our findings reveal the potential risk of natural anti-biofilm ingredients at sub-MIC to treat drug-resistance bacteria.
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Affiliation(s)
- Emad Mohammed Elken
- College of Animal Medicine, Jilin Agricultural University, Changchun, China
- The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Changchun, China
- Animal Production Department, Faculty of Agriculture, Al-Azhar University, Nasr City, Egypt
| | - Zi-ning Tan
- College of Animal Medicine, Jilin Agricultural University, Changchun, China
- The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Changchun, China
| | - Qian Wang
- The 3nd Affiliated Clinical Hospital of Changchun University of Chinese Medicine, Changchun, China
| | - Xiu-yun Jiang
- College of Animal Medicine, Jilin Agricultural University, Changchun, China
- The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Changchun, China
- College of Life Science, Jilin Agricultural University, Changchun, China
- The Engineering Research Center of Bioreactor and Drug Development, Ministry of Education, Jilin Agricultural University, Changchun, China
| | - Yu Wang
- College of Animal Medicine, Jilin Agricultural University, Changchun, China
- The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Changchun, China
| | - Yi-ming Wang
- College of Animal Medicine, Jilin Agricultural University, Changchun, China
- The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Changchun, China
- Yi-ming Wang
| | - Hong-xia Ma
- College of Animal Medicine, Jilin Agricultural University, Changchun, China
- The Key Laboratory of New Veterinary Drug Research and Development of Jilin Province, Jilin Agricultural University, Changchun, China
- College of Life Science, Jilin Agricultural University, Changchun, China
- The Engineering Research Center of Bioreactor and Drug Development, Ministry of Education, Jilin Agricultural University, Changchun, China
- *Correspondence: Hong-xia Ma
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12
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Qian J, Zhang Y, Wang P, Lu B, He Y, Tang S, Yi Z. Light alters microbiota and electron transport: Evidence for enhanced mesophilic digestion of municipal sludge. WATER RESEARCH 2022; 217:118447. [PMID: 35429889 DOI: 10.1016/j.watres.2022.118447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Revised: 04/06/2022] [Accepted: 04/08/2022] [Indexed: 06/14/2023]
Abstract
Light as an environmental factor can affect the process of anaerobic digestion, but there is no systematic study in municipal wastewater sludge mesophilic digestion. In this study, the effects of light on the performance of the anaerobic digestion system and photo-anaerobic microbiota (PAM) were evaluated in lighted anaerobic batch digesters (LABRs). The methane yield from the reactor under the dark condition (LABR0) was 179.2 mL CH4/g COD, which was lower than 305.4 mL CH4/g COD and 223.0 mL CH4/g COD (n = 3, p < 0.05) from reactors under the light intensity of 3600 lm (LABR1) and 7200 lm (LABR2), respectively. The dominant genera in the bacterial and archaeal communities were Bacillus and Methanosarcina under light conditions, Enterococcus and Methanobacterium under dark conditions. And these two bacteria acted as electroactive bacterial genera, indicating that light changes the combination of direct interspecies electron transfer (DIET) microbial partners and activates the DIET pathway for methane production. The electron conduction pathways analysis further suggests that biological DIET (bDIET) between microbial biomass, rather than DIET via conductive material (cDIET) between microbes and conductive materials, is promoted and behaves as the dominant factor enhancing methane production under light conditions. The morphology of microorganisms and the amount and properties of EPS corroborate these views. Our findings are guided to anaerobic digester constructions under the outdoor environment with light exposure.
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Affiliation(s)
- Jin Qian
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P. R. China; College of Environment, Hohai University, Nanjing 210098, P. R. China.
| | - Yuhang Zhang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P. R. China; College of Environment, Hohai University, Nanjing 210098, P. R. China
| | - Peifang Wang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P. R. China; College of Environment, Hohai University, Nanjing 210098, P. R. China
| | - Bianhe Lu
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P. R. China; College of Environment, Hohai University, Nanjing 210098, P. R. China
| | - Yuxuan He
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P. R. China; College of Environment, Hohai University, Nanjing 210098, P. R. China
| | - Sijing Tang
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P. R. China; College of Environment, Hohai University, Nanjing 210098, P. R. China
| | - Ziyang Yi
- Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing 210098, P. R. China; College of Environment, Hohai University, Nanjing 210098, P. R. China
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13
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Li S, Xu X, Lv X, Liu Y, Li J, Du G, Liu L. Combinatorial Metabolic Engineering and Enzymatic Catalysis Enable Efficient Production of Colanic Acid. Microorganisms 2022; 10:877. [PMID: 35630322 PMCID: PMC9143390 DOI: 10.3390/microorganisms10050877] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 04/01/2022] [Accepted: 04/04/2022] [Indexed: 02/04/2023] Open
Abstract
Colanic acid can promote the lifespan of humans by regulating mitochondrial homeostasis, and it has widespread applications in the field of health. However, colanic acid is produced at a low temperature (20 °C) with low titer. Using Escherichia coli K-12 MG1655, we constructed the SRP-4 strain with high colanic acid production at 30 °C by enhancing the precursor supply and relieving the regulation of transcription for colanic acid synthesis genes by the RCS system. After media optimization, the colanic acid titer increased by 579.9-fold and reached 12.2 g/L. Subsequently, we successfully purified the colanic acid hydrolase and reduced the molecular weight of colanic acid (106.854 kDa), thereby eliminating the inhibition of high-molecular-weight colanic acid on strain growth. Finally, after adding the colanic acid hydrolase (4000 U/L), the colanic acid with low molecular weight reached 24.99 g/L in 3-L bioreactor, the highest titer reported so far. This high-producing strain of colanic acid will promote the application of low-molecular-weight colanic acid in the field of health.
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Affiliation(s)
- Suwei Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; (S.L.); (X.X.); (X.L.); (Y.L.); (J.L.); (G.D.)
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Xianhao Xu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; (S.L.); (X.X.); (X.L.); (Y.L.); (J.L.); (G.D.)
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Xueqin Lv
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; (S.L.); (X.X.); (X.L.); (Y.L.); (J.L.); (G.D.)
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Yanfeng Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; (S.L.); (X.X.); (X.L.); (Y.L.); (J.L.); (G.D.)
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Jianghua Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; (S.L.); (X.X.); (X.L.); (Y.L.); (J.L.); (G.D.)
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; (S.L.); (X.X.); (X.L.); (Y.L.); (J.L.); (G.D.)
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, China; (S.L.); (X.X.); (X.L.); (Y.L.); (J.L.); (G.D.)
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China
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14
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Harshaw NS, Stella NA, Lehner KM, Romanowski EG, Kowalski RP, Shanks RMQ. Antibiotics Used in Empiric Treatment of Ocular Infections Trigger the Bacterial Rcs Stress Response System Independent of Antibiotic Susceptibility. Antibiotics (Basel) 2021; 10:antibiotics10091033. [PMID: 34572615 PMCID: PMC8470065 DOI: 10.3390/antibiotics10091033] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 12/02/2022] Open
Abstract
The Rcs phosphorelay is a bacterial stress response system that responds to envelope stresses and in turn controls several virulence-associated pathways, including capsule, flagella, and toxin biosynthesis, of numerous bacterial species. The Rcs system also affects antibiotic tolerance, biofilm formation, and horizontal gene transfer. The Rcs system of the ocular bacterial pathogen Serratia marcescens was recently demonstrated to influence ocular pathogenesis in a rabbit model of keratitis, with Rcs-defective mutants causing greater pathology and Rcs-activated strains demonstrating reduced inflammation. The Rcs system is activated by a variety of insults, including β-lactam antibiotics and polymyxin B. In this study, we developed three luminescence-based transcriptional reporters for Rcs system activity and used them to test whether antibiotics used for empiric treatment of ocular infections influence Rcs system activity in a keratitis isolate of S. marcescens. These included antibiotics to which the bacteria were susceptible and resistant. Results indicate that cefazolin, ceftazidime, polymyxin B, and vancomycin activate the Rcs system to varying degrees in an RcsB-dependent manner, whereas ciprofloxacin and tobramycin activated the promoter fusions, but in an Rcs-independent manner. Although minimum inhibitory concentration (MIC) analysis demonstrated resistance of the test bacteria to polymyxin B and vancomycin, the Rcs system was activated by sub-inhibitory concentrations of these antibiotics. Together, these data indicate that a bacterial stress system that influences numerous pathogenic phenotypes and drug-tolerance is influenced by different classes of antibiotics despite the susceptibility status of the bacterium.
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15
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Fei K, Chao HJ, Hu Y, Francis MS, Chen S. CpxR regulates the Rcs phosphorelay system in controlling the Ysc-Yop type III secretion system in Yersinia pseudotuberculosis. MICROBIOLOGY-SGM 2021; 167. [PMID: 33295859 DOI: 10.1099/mic.0.000998] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The CpxRA two-component regulatory system and the Rcs phosphorelay system are both employed by the Enterobacteriaceae family to preserve bacterial envelope integrity and function when growing under stress. Although both systems regulate several overlapping physiological processes, evidence demonstrating a molecular connection between Cpx and Rcs signalling outputs is scarce. Here, we show that CpxR negatively regulates the transcription of the rcsB gene in the Rcs phosphorelay system in Yersinia pseudotuberculosis. Interestingly, transcription of rcsB is under the control of three promoters, which were all repressed by CpxR. Critically, synthetic activation of Cpx signalling through mislocalization of the NlpE lipoprotein to the inner membrane resulted in an active form of CpxR that repressed activity of rcsB promoters. On the other hand, a site-directed mutation of the phosphorylation site at residue 51 in CpxR generated an inactive non-phosphorylated variant that was unable to regulate output from these rcsB promoters. Importantly, CpxR-mediated inhibition of rcsB transcription in turn restricted activation of the Ysc-Yop type III secretion system (T3SS). Moreover, active CpxR blocks zinc-mediated activation of Rcs signalling and the subsequent activation of lcrF transcription. Our results demonstrate a novel regulatory cascade linking CpxR-RcsB-LcrF to control production of the Ysc-Yop T3SS.
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Affiliation(s)
- Keke Fei
- University of Chinese Academy of Sciences, Beijing, PR China.,Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Hong-Jun Chao
- Present address: School of Biological & pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, PR China.,Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Matthew S Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden; Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
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16
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Reid AJ, Eade CR, Jones KJ, Jorgenson MA, Troutman JM. Tracking Colanic Acid Repeat Unit Formation from Stepwise Biosynthesis Inactivation in Escherichia coli. Biochemistry 2021; 60:2221-2230. [PMID: 34159784 DOI: 10.1021/acs.biochem.1c00314] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Colanic acid is a glycopolymer loosely associated with the outer membrane of Escherichia coli that plays a role in pathogen survival. For nearly six decades since its discovery, the functional identities of the enzymes necessary to synthesize colanic acid have yet to be assessed in full. Herein, we developed a method for detecting the lipid-linked intermediates from each step of colanic acid biosynthesis in E. coli. The accumulation of each enzyme product was made possible by inactivating sequential genes involved in colanic acid biosynthesis and upregulating the colanic acid operon by inducing rcsA transcription. LC-MS analysis revealed that these accumulated materials were consistent with the well-documented composition analysis. Recapitulating the native bioassembly of colanic acid enabled us to identify the functional roles of the last two enzymes, WcaL and WcaK, associated with the formation of the lipid-linked oligosaccharide repeating unit of colanic acid. Importantly, biochemical evidence is provided for the formation of the final glycosylation hexasaccharide product formed by WcaL and the addition of a pyruvate moiety to form a pyruvylated hexasaccharide by WcaK. These findings provide insight into the development of methods for the identification of enzyme functions during cell envelope synthesis.
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Affiliation(s)
| | | | | | - Matthew A Jorgenson
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, Arkansas 72205, United States
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17
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Sheikh SW, Ali A, Ahsan A, Shakoor S, Shang F, Xue T. Insights into Emergence of Antibiotic Resistance in Acid-Adapted Enterohaemorrhagic Escherichia coli. Antibiotics (Basel) 2021; 10:522. [PMID: 34063307 PMCID: PMC8147483 DOI: 10.3390/antibiotics10050522] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/15/2021] [Accepted: 04/29/2021] [Indexed: 12/17/2022] Open
Abstract
The emergence of multidrug-resistant pathogens presents a global challenge for treating and preventing disease spread through zoonotic transmission. The water and foodborne Enterohaemorrhagic Escherichia coli (EHEC) are capable of causing intestinal and systemic diseases. The root cause of the emergence of these strains is their metabolic adaptation to environmental stressors, especially acidic pH. Acid treatment is desired to kill pathogens, but the protective mechanisms employed by EHECs cross-protect against antimicrobial peptides and thus facilitate opportunities for survival and pathogenesis. In this review, we have discussed the correlation between acid tolerance and antibiotic resistance, highlighting the identification of novel targets for potential production of antimicrobial therapeutics. We have also summarized the molecular mechanisms used by acid-adapted EHECs, such as the two-component response systems mediating structural modifications, competitive inhibition, and efflux activation that facilitate cross-protection against antimicrobial compounds. Moving beyond the descriptive studies, this review highlights low pH stress as an emerging player in the development of cross-protection against antimicrobial agents. We have also described potential gene targets for innovative therapeutic approaches to overcome the risk of multidrug-resistant diseases in healthcare and industry.
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Affiliation(s)
- Salma Waheed Sheikh
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China;
| | - Ahmad Ali
- School of Agronomy, Anhui Agricultural University, Hefei 230036, China;
| | - Asma Ahsan
- Faculty of Life Sciences, University of Central Punjab, Lahore 54000, Punjab, Pakistan;
| | - Sidra Shakoor
- Station de Neucfchateau, CIRAD, 97130 Sainte-Marie, Capesterre Belle Eau, Guadeloupe, France;
| | - Fei Shang
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China;
| | - Ting Xue
- School of Life Sciences, Anhui Agricultural University, Hefei 230036, China;
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18
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Rodríguez-Rojas A, Baeder DY, Johnston P, Regoes RR, Rolff J. Bacteria primed by antimicrobial peptides develop tolerance and persist. PLoS Pathog 2021; 17:e1009443. [PMID: 33788905 PMCID: PMC8041211 DOI: 10.1371/journal.ppat.1009443] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 04/12/2021] [Accepted: 03/02/2021] [Indexed: 12/21/2022] Open
Abstract
Antimicrobial peptides (AMPs) are key components of innate immune defenses. Because of the antibiotic crisis, AMPs have also come into focus as new drugs. Here, we explore whether prior exposure to sub-lethal doses of AMPs increases bacterial survival and abets the evolution of resistance. We show that Escherichia coli primed by sub-lethal doses of AMPs develop tolerance and increase persistence by producing curli or colanic acid, responses linked to biofilm formation. We develop a population dynamic model that predicts that priming delays the clearance of infections and fuels the evolution of resistance. The effects we describe should apply to many AMPs and other drugs that target the cell surface. The optimal strategy to tackle tolerant or persistent cells requires high concentrations of AMPs and fast and long-lasting expression. Our findings also offer a new understanding of non-inherited drug resistance as an adaptive response and could lead to measures that slow the evolution of resistance. Animals and plants defend themselves with ancient molecules called antimicrobial peptides (AMPs) against pathogens. As more and more bacterial diseases have become drug resistant, these AMPs are considered as promising alternatives. In natural situation such as on the skin, bacteria are often exposed to low concentrations of AMPs that do no kill. Here we show that the bacterium Escherichia coli when exposed to such low concentrations becomes recalcitrant to killing concentrations of the same AMPs. We report the ways in which the bacteria alter their surface to do so. We then use a mathematical model to show that these effects caused by low concentrations can drive the evolution of resistance. From the perspective of an organism using AMPs in self-defense, the best option is to deploy high concentrations of AMPs for long. Our findings also offer a new understanding of similar drug resistance mechanisms.
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Affiliation(s)
| | | | - Paul Johnston
- Berlin Center for Genomics in Biodiversity Research, Berlin, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
| | - Roland R. Regoes
- Institute of Integrative Biology, Zürich, Switzerland
- * E-mail: (RRR); (JR)
| | - Jens Rolff
- Freie Universität Berlin, Institut für Biologie, Evolutionary Biology, Berlin, Germany
- Berlin Center for Genomics in Biodiversity Research, Berlin, Germany
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
- * E-mail: (RRR); (JR)
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19
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Huesa J, Giner-Lamia J, Pucciarelli MG, Paredes-Martínez F, García-del Portillo F, Marina A, Casino P. Structure-based analyses of Salmonella RcsB variants unravel new features of the Rcs regulon. Nucleic Acids Res 2021; 49:2357-2374. [PMID: 33638994 PMCID: PMC7913699 DOI: 10.1093/nar/gkab060] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 01/13/2021] [Accepted: 01/26/2021] [Indexed: 12/13/2022] Open
Abstract
RcsB is a transcriptional regulator that controls expression of numerous genes in enteric bacteria. RcsB accomplishes this role alone or in combination with auxiliary transcriptional factors independently or dependently of phosphorylation. To understand the mechanisms by which RcsB regulates such large number of genes, we performed structural studies as well as in vitro and in vivo functional studies with different RcsB variants. Our structural data reveal that RcsB binds promoters of target genes such as rprA and flhDC in a dimeric active conformation. In this state, the RcsB homodimer docks the DNA-binding domains into the major groove of the DNA, facilitating an initial weak read-out of the target sequence. Interestingly, comparative structural analyses also show that DNA binding may stabilize an active conformation in unphosphorylated RcsB. Furthermore, RNAseq performed in strains expressing wild-type or several RcsB variants provided new insights into the contribution of phosphorylation to gene regulation and assign a potential role of RcsB in controlling iron metabolism. Finally, we delimited the RcsB box for homodimeric active binding to DNA as the sequence TN(G/A)GAN4TC(T/C)NA. This RcsB box was found in promoter, intergenic and intragenic regions, facilitating both increased or decreased gene transcription.
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Affiliation(s)
- Juanjo Huesa
- Departamento de Bioquímica y Biología Molecular, Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain.,Instituto universitario de Biotecnologia i Biomedicina (BIOTECMED), Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain
| | - Joaquín Giner-Lamia
- Laboratorio de Patógenos Bacterianos Intracelulares. Centro Nacional de Biotecnología (CNB)-CSIC. Darwin 3, 28049 Madrid. Spain.,Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Campus Montegancedo, E-28223 Pozuelo de Alarcón, Madrid, Spain.,Departamento de Biotecnología y Biología Vegetal, ETSI Agronómica, Alimentaria y de Biosistemas, Universidad Politócnica de Madrid, 28040 Madrid, Spain
| | - M Graciela Pucciarelli
- Laboratorio de Patógenos Bacterianos Intracelulares. Centro Nacional de Biotecnología (CNB)-CSIC. Darwin 3, 28049 Madrid. Spain.,Centro de Biología Molecular 'Severo Ochoa' (CBMSO)-CSIC. Departamento de Biología Molecular. Universidad Autónoma de Madrid, Madrid, Spain
| | - Francisco Paredes-Martínez
- Departamento de Bioquímica y Biología Molecular, Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain.,Instituto universitario de Biotecnologia i Biomedicina (BIOTECMED), Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain
| | - Francisco García-del Portillo
- Laboratorio de Patógenos Bacterianos Intracelulares. Centro Nacional de Biotecnología (CNB)-CSIC. Darwin 3, 28049 Madrid. Spain
| | - Alberto Marina
- Department of Genomic and Proteomic, Instituto de Biomedicina de Valencia (IBV-CSIC), Jaume Roig 11, 46010 Valencia, Spain.,Group 739 of the Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBERER) del Instituto de Salud Carlos III, Spain
| | - Patricia Casino
- Departamento de Bioquímica y Biología Molecular, Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain.,Instituto universitario de Biotecnologia i Biomedicina (BIOTECMED), Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain.,Group 739 of the Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBERER) del Instituto de Salud Carlos III, Spain
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20
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Meng J, Young G, Chen J. The Rcs System in Enterobacteriaceae: Envelope Stress Responses and Virulence Regulation. Front Microbiol 2021; 12:627104. [PMID: 33658986 PMCID: PMC7917084 DOI: 10.3389/fmicb.2021.627104] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 01/18/2021] [Indexed: 11/13/2022] Open
Abstract
The bacterial cell envelope is a protective barrier at the frontline of bacterial interaction with the environment, and its integrity is regulated by various stress response systems. The Rcs (regulator of capsule synthesis) system, a non-orthodox two-component regulatory system (TCS) found in many members of the Enterobacteriaceae family, is one of the envelope stress response pathways. The Rcs system can sense envelope damage or defects and regulate the transcriptome to counteract stress, which is particularly important for the survival and virulence of pathogenic bacteria. In this review, we summarize the roles of the Rcs system in envelope stress responses (ESRs) and virulence regulation. We discuss the environmental and intrinsic sources of envelope stress that cause activation of the Rcs system with an emphasis on the role of RcsF in detection of envelope stress and signal transduction. Finally, the different regulation mechanisms governing the Rcs system's control of virulence in several common pathogens are introduced. This review highlights the important role of the Rcs system in the environmental adaptation of bacteria and provides a theoretical basis for the development of new strategies for control, prevention, and treatment of bacterial infections.
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Affiliation(s)
- Jiao Meng
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Glenn Young
- Department of Food Science and Technology, University of California, Davis, Davis, CA, United States
| | - Jingyu Chen
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
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21
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Chaudhry W, Lee E, Worthy A, Weiss Z, Grabowicz M, Vega N, Levin B. Mucoidy, a general mechanism for maintaining lytic phage in populations of bacteria. FEMS Microbiol Ecol 2021; 96:5897354. [PMID: 32845324 PMCID: PMC7532286 DOI: 10.1093/femsec/fiaa162] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 08/11/2020] [Indexed: 12/19/2022] Open
Abstract
We present evidence that phage resistance resulting from overproduction of exopolysaccharides, mucoidy, provides a general answer to the longstanding question of how lytic viruses are maintained in populations dominated by bacteria upon which they cannot replicate. In serial transfer culture, populations of mucoid Escherichia coli MG1655 that are resistant to lytic phages with different receptors, and thereby requiring independent mutations for surface resistance, are capable of maintaining these phages with little effect on their total density. Based on the results of our analysis of a mathematical model, we postulate that the maintenance of phage in populations dominated by mucoid cells can be attributed primarily to high rates of transition from the resistant mucoid states to susceptible non-mucoid states. Our tests with both population dynamic and single cell experiments as well as genomic analysis are consistent with this hypothesis. We discuss reasons for the generalized resistance of these mucoid E. coli, and the genetic and molecular mechanisms responsible for the high rate of transition from mucoid to sensitive states responsible for the maintenance of lytic phage in mucoid populations of E. coli.
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Affiliation(s)
- Waqas Chaudhry
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Esther Lee
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Andrew Worthy
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Zoe Weiss
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Marcin Grabowicz
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA.,Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA 30322, USA.,Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Nicole Vega
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Bruce Levin
- Department of Biology, Emory University, Atlanta, GA 30322, USA.,Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, GA 30322, USA
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22
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Regulator RcsB Controls Prodigiosin Synthesis and Various Cellular Processes in Serratia marcescens JNB5-1. Appl Environ Microbiol 2021; 87:AEM.02052-20. [PMID: 33158890 DOI: 10.1128/aem.02052-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 10/30/2020] [Indexed: 12/18/2022] Open
Abstract
Prodigiosin (PG), a red linear tripyrrole pigment normally secreted by Serratia marcescens, has received attention for its reported immunosuppressive, antimicrobial, and anticancer properties. Although several genes have been shown to be important for prodigiosin synthesis, information on the regulatory mechanisms behind this cellular process remains limited. In this work, we identified that the transcriptional regulator RcsB encoding gene BVG90_13250 (rcsB) negatively controlled prodigiosin biosynthesis in S. marcescens Disruption of rcsB conferred a remarkably increased production of prodigiosin. This phenotype corresponded to negative control of transcription of the prodigiosin-associated pig operon by RcsB, probably by binding to the promoter region of the prodigiosin synthesis positive regulator FlhDC. Moreover, using transcriptomics and further experiments, we revealed that RcsB also controlled some other important cellular processes, including swimming and swarming motilities, capsular polysaccharide production, biofilm formation, and acid resistance (AR), in S. marcescens Collectively, this work proposes that RcsB is a prodigiosin synthesis repressor in S. marcescens and provides insight into the regulatory mechanism of RcsB in cell motility, capsular polysaccharide production, and acid resistance in S. marcescens IMPORTANCE RcsB is a two-component response regulator in the Rcs phosphorelay system, and it plays versatile regulatory functions in Enterobacteriaceae However, information on the function of the RcsB protein in bacteria, especially in S. marcescens, remains limited. In this work, we illustrated experimentally that the RcsB protein was involved in diverse cellular processes in S. marcescens, including prodigiosin synthesis, cell motility, capsular polysaccharide production, biofilm formation, and acid resistance. Additionally, the regulatory mechanism of the RcsB protein in these cellular processes was investigated. In conclusion, this work indicated that RcsB could be a regulator for prodigiosin synthesis and provides insight into the function of the RcsB protein in S. marcescens.
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23
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Regulation of gene expression by protein lysine acetylation in Salmonella. J Microbiol 2020; 58:979-987. [PMID: 33201432 DOI: 10.1007/s12275-020-0483-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/12/2020] [Accepted: 10/12/2020] [Indexed: 10/23/2022]
Abstract
Protein lysine acetylation influences many physiological functions, such as gene regulation, metabolism, and disease in eukaryotes. Although little is known about the role of lysine acetylation in bacteria, several reports have proposed its importance in various cellular processes. Here, we discussed the function of the protein lysine acetylation and the post-translational modifications (PTMs) of histone-like proteins in bacteria focusing on Salmonella pathogenicity. The protein lysine residue in Salmonella is acetylated by the Pat-mediated enzymatic pathway or by the acetyl phosphate-mediated non-enzymatic pathway. In Salmonella, the acetylation of lysine 102 and lysine 201 on PhoP inhibits its protein activity and DNA-binding, respectively. Lysine acetylation of the transcriptional regulator, HilD, also inhibits pathogenic gene expression. Moreover, it has been reported that the protein acetylation patterns significantly differ in the drug-resistant and -sensitive Salmonella strains. In addition, nucleoid-associated proteins such as histone-like nucleoid structuring protein (H-NS) are critical for the gene silencing in bacteria, and PTMs in H-NS also affect the gene expression. In this review, we suggest that protein lysine acetylation and the post-translational modifications of H-NS are important factors in understanding the regulation of gene expression responsible for pathogenicity in Salmonella.
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24
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Bujak K, Decewicz P, Kaminski J, Radlinska M. Identification, Characterization, and Genomic Analysis of Novel Serratia Temperate Phages from a Gold Mine. Int J Mol Sci 2020; 21:ijms21186709. [PMID: 32933193 PMCID: PMC7556043 DOI: 10.3390/ijms21186709] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/04/2020] [Accepted: 09/10/2020] [Indexed: 12/14/2022] Open
Abstract
Bacteria of the genus Serratia inhabit a variety of ecological niches like water, soil, and the bodies of animals, and have a wide range of lifestyles. Currently, the complete genome sequences of 25 Serratia phages are available in the NCBI database. All of them were isolated from nutrient-rich environments like sewage, with the use of clinical Serratia strains as hosts. In this study, we identified a novel Serratia myovirus named vB_SspM_BZS1. Both the phage and its host Serratia sp. OS31 were isolated from the same oligotrophic environment, namely, an abandoned gold mine (Zloty Stok, Poland). The BZS1 phage was thoroughly characterized here in terms of its genomics, morphology, and infection kinetics. We also demonstrated that Serratia sp. OS31 was lysogenized by mitomycin-inducible siphovirus vB_SspS_OS31. Comparative analyses revealed that vB_SspM_BZS1 and vB_SspS_OS31 were remote from the known Serratia phages. Moreover, vB_SspM_BZS1 was only distantly related to other viruses. However, we discovered similar prophage sequences in genomes of various bacteria here. Additionally, a protein-based similarity network showed a high diversity of Serratia phages in general, as they were scattered across nineteen different clusters. In summary, this work broadened our knowledge on the diverse relationships of Serratia phages.
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25
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Meng J, Bai J, Xu J, Huang C, Chen J. Differential regulation of physiological activities by RcsB and OmpR in Yersinia enterocolitica. FEMS Microbiol Lett 2020; 366:5584338. [PMID: 31598670 DOI: 10.1093/femsle/fnz210] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 10/07/2019] [Indexed: 12/15/2022] Open
Abstract
A thorough understanding of the mechanisms of Rcs and EnvZ/OmpR phosphorelay systems that allow Yersinia enterocolitica to thrive in various environments is crucial to prevent and control Y. enterocolitica infections. In this study, we showed that RcsB and OmpR have the ability to function differently in modulating a diverse array of physiological processes in Y. enterocolitica. The rcsB mutant stimulated flagella biosynthesis and increased motility, biofilm formation and c-di-GMP production by upregulating flhDC, hmsHFRS and hmsT. However, mutation in ompR exhibited a non-motile phenotype due to the lack of flagella. Biofilm formation was reduced and less c-di-GMP was produced through the downregulation of flhDC, hmsHFRS and hmsT expression when Y. enterocolitica was exposed to low osmolarity conditions. Furthermore, OmpR was identified to be important for Y. enterocolitica to grow in extreme temperature conditions. Importantly, ompR mutations in Y. enterocolitica were more sensitive to polymyxin B and sodium dodecyl sulfate than rcsB mutations. Since motility, biofilm formation and environmental tolerance are critical for bacterial colonization of the host, these findings indicated that OmpR is more critical than RcsB in shaping the pathogenic phenotype of Y. enterocolitica.
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Affiliation(s)
- Jiao Meng
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.,Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Jiaqi Bai
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.,Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Junhong Xu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.,Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Can Huang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.,Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Jingyu Chen
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.,Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
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26
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Yuan L, Li X, Du L, Su K, Zhang J, Liu P, He Q, Zhang Z, Peng D, Shen L, Qiu J, Li Y. RcsAB and Fur Coregulate the Iron-Acquisition System via entC in Klebsiella pneumoniae NTUH-K2044 in Response to Iron Availability. Front Cell Infect Microbiol 2020; 10:282. [PMID: 32587833 PMCID: PMC7298118 DOI: 10.3389/fcimb.2020.00282] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 05/12/2020] [Indexed: 01/21/2023] Open
Abstract
The iron acquisition system is an essential virulence factor for human infection and is under tight regulatory control in a variety of pathogens. Ferric-uptake regulator (Fur) is one of Fe2+-responsive transcription factor that maintains iron homeostasis, and the regulator of capsule synthesis (Rcs) is known to regulate exopolysaccharide biosynthesis. We speculate the Rcs may involve in iron-acquisition given the identified regulator box in the upstream of entC that participated in the biosynthesis of enterobactin. To study the coregulation by RcsAB and Fur of entC, we measured the β-galactosidase activity and relative mRNA expression of entC in WT and mutant strains. The RcsAB- and Fur-protected regions were identified by an electrophoretic mobility shift assay (EMSA) and a DNase I footprinting assay. A regulatory cascade was identified with which Fur repressed rcsA expression and reduced RcsAB and entC expression. Our study demonstrated that entC was coregulated by two different transcriptional regulators, namely, RcsAB and Fur, in response to iron availability in Klebsiella pneumoniae.
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Affiliation(s)
- Lingyue Yuan
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Xuan Li
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Ling Du
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Kewen Su
- Hangzhou Hospital for the Prevention and Treatment of Occupational Disease, Hangzhou, China
| | - Jiaxue Zhang
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Pin Liu
- Nanjing Center for Disease Control and Prevention, Nanjing, China
| | - Qiang He
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Zhongshuang Zhang
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Dan Peng
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Lifei Shen
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Jingfu Qiu
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
| | - Yingli Li
- School of Public Health and Management, Chongqing Medical University, Chongqing, China
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27
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Transcriptomic analysis reveals the role of RcsB in suppressing bacterial chemotaxis, flagellar assembly and infection in Yersinia enterocolitica. Curr Genet 2020; 66:971-988. [PMID: 32488337 DOI: 10.1007/s00294-020-01083-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 05/01/2020] [Accepted: 05/01/2020] [Indexed: 12/17/2022]
Abstract
Defining the Rcs (Regulator of Capsule Synthesis) regulon in Enterobacteriaceae has been the major focus of several recent studies. The overall role of the Rcs system in Yersinia enterocolitica is largely unknown. Our previous study showed that RcsB inhibits motility, biofilm formation and c-di-GMP production by negatively regulating flhDC, hmsHFRS and hmsT expression. To identify other cellular functions regulated by the RcsB, gene expression profiles of the wild type and ΔrcsB mutant were compared by RNA-Seq in this study. A total of 132 differentially expressed genes regulated by the RcsB have been identified, of which 114 were upregulated and 18 were downregulated. Further, the results of RNA sequencing were discussed with a focus on the predictive roles of RcsB in the inhibition of bacterial chemotaxis, flagellar assembly and infection. To confirm these predictions, we experimentally verified that the ΔrcsB mutant activated chemotactic behavior and flagella biosynthesis, and exhibited enhanced adhesion and invasion of Y. enterocolitica to Caco-2 cells. Although RcsB largely inhibits these physiological activities, the presence of RcsB is still of great significance for optimizing the survival of Y. enterocolitica as evidenced by our previous report that RcsB confers some level of resistance to the cationic antimicrobial peptide polymyxin B in Y. enterocolitica. Overall, the information provided in this study complements our understanding of Rcs phosphorelay in the regulation of Y. enterocolitica pathogenicity, and, simultaneously, provides clues to additional roles of the Rcs system in other members of family Enterobacteriaceae.
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28
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Navasa N, Ferrero MÁ, Rodríguez-Aparicio LB, Monteagudo-Mera A, Gutiérrez S, Martínez-Blanco H. The role of RcsA in the adaptation and survival of Escherichia coli K92. FEMS Microbiol Lett 2020; 366:5476499. [PMID: 31089698 DOI: 10.1093/femsle/fnz082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/18/2019] [Indexed: 12/26/2022] Open
Abstract
The Rcs phosphorelay is a two-component signal transduction system that senses stressful environmental signals such as desiccation or low temperatures, which serve as natural inducers in bacteria. RcsA is an important coregulator in this system involved in some functions regulated by the Rcs system, including biofilm formation and capsule synthesis. In this sense, we previously showed that RcsA is necessary for colanic acid synthesis in Escherichia coli K92. Here, using an E. coli K92ΔrcsA mutant lacking rcsA gene we further characterize the implications of RcsA on E. coli K92 survival under osmotic and oxidative stressful conditions, and bacterial attachment and biofilm formation on both biotic and abiotic surfaces. Our results show that RcsA protects E. coli K92 against osmotic and, especially, oxidative stress at low temperatures. In addition, RcsA did not interfere in biofilm formation in any surface tested, including polystyrene, stainless steel, silicone, Teflon, aluminum and glass. By contrast, deletion of rcsA increased bacterial attachment to the caco-2 cells monolayer used as biotic surface.
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Affiliation(s)
- Nicolás Navasa
- Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Miguel Ángel Ferrero
- Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Leandro B Rodríguez-Aparicio
- Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Andrea Monteagudo-Mera
- Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Sergio Gutiérrez
- Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
| | - Honorina Martínez-Blanco
- Departamento de Biología Molecular, Área de Bioquímica y Biología Molecular, Universidad de León, Campus de Vegazana s/n, 24071 León, Spain
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29
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Meng J, Huang C, Huang X, Liu D, Han B, Chen J. Osmoregulated Periplasmic Glucans Transmit External Signals Through Rcs Phosphorelay Pathway in Yersinia enterocolitica. Front Microbiol 2020; 11:122. [PMID: 32117145 PMCID: PMC7013093 DOI: 10.3389/fmicb.2020.00122] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 01/20/2020] [Indexed: 01/13/2023] Open
Abstract
Fast response to environmental changes plays a key role in the transmission and pathogenesis of Yersinia enterocolitica. Osmoregulated periplasmic glucans (OPGs) are known to be involved in environmental perception of several Enterobacteriaceae pathogens; however, the biological function of OPGs in Y. enterocolitica is still unclear. In this study, we investigated the role of OPGs in Y. enterocolitica by deleting the opgGH operon encoding enzymes responsible for OPGs biosynthesis. Complete loss of OPGs in the ΔopgGH mutant resulted in decreased motility, c-di-GMP production, biofilm formation and smaller cell size, whereas the overproduction of OPGs through restoration of opgGH expression promoted c-di-GMP/biofilm production and increased antibiotic resistance of Y. enterocolitica. Gene expression analysis revealed that opgGH deletion reduced transcription of flhDC, ftsAZ, hmsT and hmsHFRS genes regulated by the Rcs phosphorelay system, whereas additional deletion of rcs family genes (rcsF, rcsC, or rcsB) reversed this effect and restored motility and c-di-GMP/biofilm production but further reduced cell size. Furthermore, disruption of the Rcs phosphorelay increased the motility and promoted the induction of biofilm and c-di-GMP production regulated by OPGs through upregulating the expression of flhDC, hmsHFRS, and hmsT. However, deletion of genes encoding the EnvZ/OmpR phosphorelay downregulated the flhDC, hmsHFRS and hmsT expression, leading to the decreased motility and prevented the induction of biofilm and c-di-GMP production regulated by OPGs. These results indicated that Rcs phosphorelay had the effect on OPGs-mediated functional responses in Y. enterocolitica. Our findings disclose part of the biological role of OPGs and the underlying molecular mechanisms associated with Rcs system in the regulation of the pathogenic phenotype in Y. enterocolitica.
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Affiliation(s)
- Jiao Meng
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Can Huang
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Xiaoning Huang
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Dingyu Liu
- Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin, China
| | - Beizhong Han
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
| | - Jingyu Chen
- Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.,Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China
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30
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Delhaye A, Collet JF, Laloux G. A Fly on the Wall: How Stress Response Systems Can Sense and Respond to Damage to Peptidoglycan. Front Cell Infect Microbiol 2019; 9:380. [PMID: 31799211 PMCID: PMC6863773 DOI: 10.3389/fcimb.2019.00380] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 10/24/2019] [Indexed: 01/10/2023] Open
Abstract
The envelope of Gram-negative bacteria is critical for survival across a wide range of environmental conditions. The inner membrane, the periplasm and the outer membrane form a complex compartment, home to many essential processes. Hence, constant monitoring by envelope stress response systems ensure correct biogenesis of the envelope and maintain its homeostasis. Inside the periplasm, the cell wall, made of peptidoglycan, has been under the spotlight for its critical role in bacterial growth as well as being the target of many antibiotics. While much research is centered around understanding the role of the many enzymes involved in synthesizing the cell wall, much less is known about how the cell can detect perturbations of this assembly process, and how it is regulated during stress. In this review, we explore the current knowledge of cell wall defects sensing by stress response systems, mainly in the model bacterium Escherichia coli. We also discuss how these systems can respond to cell wall perturbations to increase fitness, and what implications this has on cell wall regulation.
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Affiliation(s)
- Antoine Delhaye
- de Duve Institute, UCLouvain, Brussels, Belgium.,Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Brussels, Belgium
| | - Jean-François Collet
- de Duve Institute, UCLouvain, Brussels, Belgium.,Walloon Excellence in Life Sciences and Biotechnology (WELBIO), Brussels, Belgium
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31
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Farizano JV, García-Pastor L, Casadesús J, Delgado MA. Transcriptional regulation of the Salmonella enterica std fimbrial operon by the RcsCDB system. MICROBIOLOGY-SGM 2019; 165:1245-1250. [PMID: 31486760 DOI: 10.1099/mic.0.000854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In Salmonella enterica serovar Typhimurium, the RcsCDB regulatory system controls the expression of genes involved in synthesis of colanic acid, formation of flagella and virulence. Here, we show that activation of the RcsCDB system downregulates expression of std, an operon that encodes fimbriae involved in Salmonella attachment to the mucus layer in the large intestine. Bioinformatic analysis predicts the existence of an RcsB-binding site located 180 bp upstream to the +1 transcription start site of the std promoter, and electrophoretic mobility shift assays confirm that RcsB binds the std promoter region in vitro. This study adds RcsB to the list of regulators of std transcription and provides an example of modulation of fimbriae synthesis by a signal transduction system.
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Affiliation(s)
- Juan V Farizano
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI - San, Miguel de Tucumán, Argentina
| | - Lucia García-Pastor
- Departamento de Genética, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain
| | - Josep Casadesús
- Departamento de Genética, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain
| | - Monica A Delgado
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI - San, Miguel de Tucumán, Argentina
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32
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Casino P, Miguel-Romero L, Huesa J, García P, García-Del Portillo F, Marina A. Conformational dynamism for DNA interaction in the Salmonella RcsB response regulator. Nucleic Acids Res 2019; 46:456-472. [PMID: 29186528 PMCID: PMC5758874 DOI: 10.1093/nar/gkx1164] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 11/08/2017] [Indexed: 11/29/2022] Open
Abstract
The RcsCDB phosphorelay system controls an extremely large regulon in Enterobacteriaceae that involves processes such as biofilm formation, flagella production, synthesis of extracellular capsules and cell division. Therefore, fine-tuning of this system is essential for virulence in pathogenic microorganisms of this group. The final master effector of the RcsCDB system is the response regulator (RR) RcsB, which activates or represses multiple genes by binding to different promoter regions. This regulatory activity of RcsB can be done alone or in combination with additional transcriptional factors in phosphorylated or dephosphorylated states. The capacity of RcsB to interact with multiple promoters and partners, either dephosphorylated or phosphorylated, suggests an extremely conformational dynamism for this RR. To shed light on the activation mechanism of RcsB and its implication on promoter recognition, we solved the crystal structure of full-length RcsB from Salmonella enterica serovar Typhimurium in the presence and absence of a phosphomimetic molecule BeF3−. These two novel structures have guided an extensive site-directed mutagenesis study at the structural and functional level that confirms RcsB conformational plasticity and dynamism. Our data allowed us to propose a β5-T switch mechanism where phosphorylation is coupled to alternative DNA binding ways and which highlights the conformational dynamism of RcsB to be so pleiotropic.
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Affiliation(s)
- Patricia Casino
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Dr Moliner 50, 46100 Burjassot, Spain.,Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain
| | - Laura Miguel-Romero
- Department of Genomic and Proteomic, Instituto de Biomedicina de Valencia (IBV-CSIC), Jaume Roig 11, 46010 Valencia, Spain
| | - Juanjo Huesa
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Dr Moliner 50, 46100 Burjassot, Spain.,Estructura de Recerca Interdisciplinar en Biotecnologia i Biomedicina (ERI BIOTECMED), Universitat de València. Dr Moliner 50, 46100 Burjassot, Spain
| | - Pablo García
- Laboratorio de Patógenos Bacterianos Intracelulares, Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB-CSIC), Darwin, 3. 28049 Madrid, Spain
| | - Francisco García-Del Portillo
- Laboratorio de Patógenos Bacterianos Intracelulares, Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología (CNB-CSIC), Darwin, 3. 28049 Madrid, Spain
| | - Alberto Marina
- Department of Genomic and Proteomic, Instituto de Biomedicina de Valencia (IBV-CSIC), Jaume Roig 11, 46010 Valencia, Spain.,Group 739 of the Centro de Investigación Biomédica en Red sobre Enfermedades Raras (CIBERER) del Instituto de Salud Carlos III, Spain
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Minnullina L, Pudova D, Shagimardanova E, Shigapova L, Sharipova M, Mardanova A. Comparative Genome Analysis of Uropathogenic Morganella morganii Strains. Front Cell Infect Microbiol 2019; 9:167. [PMID: 31231616 PMCID: PMC6558430 DOI: 10.3389/fcimb.2019.00167] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 05/03/2019] [Indexed: 12/02/2022] Open
Abstract
Morganella morganii is an opportunistic bacterial pathogen shown to cause a wide range of clinical and community-acquired infections. This study was aimed at sequencing and comparing the genomes of three M. morganii strains isolated from the urine samples of patients with community-acquired urinary tract infections. Draft genome sequencing was conducted using the Illumina HiSeq platform. The genomes of MM 1, MM 4, and MM 190 strains have a size of 3.82–3.97 Mb and a GC content of 50.9–51%. Protein-coding sequences (CDS) represent 96.1% of the genomes, RNAs are encoded by 2.7% of genes and pseudogenes account for 1.2% of the genomes. The pan-genome containes 4,038 CDS, of which 3,279 represent core genes. Six to ten prophages and 21–33 genomic islands were identified in the genomes of MM 1, MM 4, and MM 190. More than 30 genes encode capsular biosynthesis proteins, an average of 60 genes encode motility and chemotaxis proteins, and about 70 genes are associated with fimbrial biogenesis and adhesion. We determined that all strains contained urease gene cluster ureABCEFGD and had a urease activity. Both MM 4 and MM 190 strains are capable of hemolysis and their activity correlates well with a cytotoxicity level on T-24 bladder carcinoma cells. These activities were associated with expression of RTX toxin gene hlyA, which was introduced into the genomes by a phage similar to Salmonella phage 118970_sal4.
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Affiliation(s)
- Leyla Minnullina
- Laboratory of Microbial Biotechnology, Institute of Fundamental Medicine and Biology, Kazan (Volga region) Federal University, Kazan, Russia
| | - Daria Pudova
- Laboratory of Microbial Biotechnology, Institute of Fundamental Medicine and Biology, Kazan (Volga region) Federal University, Kazan, Russia
| | - Elena Shagimardanova
- Laboratory of Extreme Biology, Institute of Fundamental Medicine and Biology, Kazan (Volga region) Federal University, Kazan, Russia
| | - Leyla Shigapova
- Laboratory of Extreme Biology, Institute of Fundamental Medicine and Biology, Kazan (Volga region) Federal University, Kazan, Russia
| | - Margarita Sharipova
- Laboratory of Microbial Biotechnology, Institute of Fundamental Medicine and Biology, Kazan (Volga region) Federal University, Kazan, Russia
| | - Ayslu Mardanova
- Laboratory of Microbial Biotechnology, Institute of Fundamental Medicine and Biology, Kazan (Volga region) Federal University, Kazan, Russia
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Tierney AR, Rather PN. Roles of two-component regulatory systems in antibiotic resistance. Future Microbiol 2019; 14:533-552. [PMID: 31066586 DOI: 10.2217/fmb-2019-0002] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Two-component regulatory systems (TCSs) are a major mechanism by which bacteria sense and respond to changes in their environment. TCSs typically consist of two proteins that bring about major regulation of the cell genome through coordinated action mediated by phosphorylation. Environmental conditions that activate TCSs are numerous and diverse and include exposure to antibiotics as well as conditions inside a host. The resulting regulatory action often involves activation of antibiotic defenses and changes to cell physiology that increase antibiotic resistance. Examples of resistance mechanisms enacted by TCSs contained in this review span those found in both Gram-negative and Gram-positive species and include cell surface modifications, changes in cell permeability, increased biofilm formation, and upregulation of antibiotic-degrading enzymes.
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Affiliation(s)
- Aimee Rp Tierney
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA, 30322 USA
| | - Philip N Rather
- Department of Microbiology & Immunology, Emory University School of Medicine, Atlanta, GA, 30322 USA.,Research Service, Department of Veterans' Affairs, Atlanta VA Health Care System, Decatur, GA, 30033 USA
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Thanikkal EJ, Gahlot DK, Liu J, Fredriksson Sundbom M, Gurung JM, Ruuth K, Francis MK, Obi IR, Thompson KM, Chen S, Dersch P, Francis MS. The Yersinia pseudotuberculosis Cpx envelope stress system contributes to transcriptional activation of rovM. Virulence 2019; 10:37-57. [PMID: 30518290 PMCID: PMC6298763 DOI: 10.1080/21505594.2018.1556151] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The Gram-negative enteropathogen Yersinia pseudotuberculosis possesses a number of regulatory systems that detect cell envelope damage caused by noxious extracytoplasmic stresses. The CpxA sensor kinase and CpxR response regulator two-component regulatory system is one such pathway. Active Cpx signalling upregulates various factors designed to repair and restore cell envelope integrity. Concomitantly, this pathway also down-regulates key determinants of virulence. In Yersinia, cpxA deletion accumulates high levels of phosphorylated CpxR (CpxR~P). Accumulated CpxR~P directly repressed rovA expression and this limited expression of virulence-associated processes. A second transcriptional regulator, RovM, also negatively regulates rovA expression in response to nutrient stress. Hence, this study aimed to determine if CpxR~P can influence rovA expression through control of RovM levels. We determined that the active CpxR~P isoform bound to the promoter of rovM and directly induced its expression, which naturally associated with a concurrent reduction in rovA expression. Site-directed mutagenesis of the CpxR~P binding sequence in the rovM promoter region desensitised rovM expression to CpxR~P. These data suggest that accumulated CpxR~P inversely manipulates the levels of two global transcriptional regulators, RovA and RovM, and this would be expected to have considerable influence on Yersinia pathophysiology and metabolism.
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Affiliation(s)
- Edvin J Thanikkal
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Dharmender K Gahlot
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Junfa Liu
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | | | - Jyoti M Gurung
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Kristina Ruuth
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Monika K Francis
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Ikenna R Obi
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Karl M Thompson
- c Department of Microbiology , College of Medicine, Howard University , Washington , DC , USA.,d Interdisciplinary Research Building , Howard University , Washington , DC , USA
| | - Shiyun Chen
- e Key Laboratory of Special Pathogens and Biosafety , Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan , China
| | - Petra Dersch
- f Department of Molecular Infection Biology , Helmholtz Centre for Infection Research , Braunschweig , Germany
| | - Matthew S Francis
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
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Rcs Phosphorelay Activation in Cardiolipin-Deficient Escherichia coli Reduces Biofilm Formation. J Bacteriol 2019; 201:JB.00804-18. [PMID: 30782633 DOI: 10.1128/jb.00804-18] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2019] [Accepted: 02/07/2019] [Indexed: 11/20/2022] Open
Abstract
Biofilm formation is a complex process that requires a number of transcriptional, proteomic, and physiological changes to enable bacterial survival. The lipid membrane presents a barrier to communication between the machinery within bacteria and the physical and chemical features of their extracellular environment, and yet little is known about how the membrane influences biofilm development. We found that depleting the anionic phospholipid cardiolipin reduces biofilm formation in Escherichia coli cells by as much as 50%. The absence of cardiolipin activates the regulation of colanic acid synthesis (Rcs) envelope stress response, which represses the production of flagella, disrupts initial biofilm attachment, and reduces biofilm growth. We demonstrate that a reduction in the concentration of cardiolipin impairs translocation of proteins across the inner membrane, which we hypothesize activates the Rcs pathway through the outer membrane lipoprotein RcsF. Our study demonstrates a molecular connection between the composition of membrane phospholipids and biofilm formation in E. coli and suggests that altering lipid biosynthesis may be a viable approach for altering biofilm formation and possibly other multicellular phenotypes related to bacterial adaptation and survival.IMPORTANCE There is a growing interest in the role of lipid membrane composition in the physiology and adaptation of bacteria. We demonstrate that a reduction in the anionic phospholipid cardiolipin impairs biofilm formation in Escherichia coli cells. Depleting cardiolipin reduced protein translocation across the inner membrane and activated the Rcs envelope stress response. Consequently, cardiolipin depletion produced cells lacking assembled flagella, which impacted their ability to attach to surfaces and seed the earliest stage in biofilm formation. This study provides empirical evidence for the role of anionic phospholipid homeostasis in protein translocation and its effect on biofilm development and highlights modulation of the membrane composition as a potential method of altering bacterial phenotypes related to adaptation and survival.
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Abstract
The cell envelope is the first line of defense between a bacterium and the world-at-large. Often, the initial steps that determine the outcome of chemical warfare, bacteriophage infections, and battles with other bacteria or the immune system greatly depend on the structure and composition of the bacterial cell surface. One of the most studied bacterial surface molecules is the glycolipid known as lipopolysaccharide (LPS), which is produced by most Gram-negative bacteria. Much of the initial attention LPS received in the early 1900s was owed to its ability to stimulate the immune system, for which the glycolipid was commonly known as endotoxin. It was later discovered that LPS also creates a permeability barrier at the cell surface and is a main contributor to the innate resistance that Gram-negative bacteria display against many antimicrobials. Not surprisingly, these important properties of LPS have driven a vast and still prolific body of literature for more than a hundred years. LPS research has also led to pioneering studies in bacterial envelope biogenesis and physiology, mostly using Escherichia coli and Salmonella as model systems. In this review, we will focus on the fundamental knowledge we have gained from studies of the complex structure of the LPS molecule and the biochemical pathways for its synthesis, as well as the transport of LPS across the bacterial envelope and its assembly at the cell surface.
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Conley ZC, Carlson-Banning KM, Carter AG, de la Cova A, Song Y, Zechiedrich L. Sugar and iron: Toward understanding the antibacterial effect of ciclopirox in Escherichia coli. PLoS One 2019; 14:e0210547. [PMID: 30633761 PMCID: PMC6329577 DOI: 10.1371/journal.pone.0210547] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Accepted: 12/27/2018] [Indexed: 12/11/2022] Open
Abstract
New antibiotics are needed against antibiotic-resistant gram-negative bacteria. The repurposed antifungal drug, ciclopirox, equally blocks antibiotic-susceptible or multidrug-resistant Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae clinical isolates, indicating that it is not affected by existing resistance mechanisms. Toward understanding how ciclopirox blocks growth, we screened E. coli mutant strains and found that disruption of genes encoding products involved in galactose salvage, enterobacterial common antigen synthesis, and transport of the iron binding siderophore, enterobactin, lowered the minimum inhibitory concentration of ciclopirox needed to block growth of the mutant compared to the isogenic parent strain. We found that ciclopirox induced enterobactin production and that this effect is strongly affected by the deletion of the galactose salvage genes encoding UDP-galactose 4-epimerase, galE, or galactose-1-phosphate uridylyltransferase, galT. As disruption of ECA synthesis activates the regulation of capsular synthesis (Rcs) phosphorelay, which inhibits bacterial swarming and promotes biofilm development, we test whether ciclopirox prevents activation of the Rcs pathway. Sub-inhibitory concentrations of ciclopirox increased swarming of the E. coli laboratory K12 strain BW25113 but had widely varying effects on swarming or surface motility of clinical isolate E. coli, A. baumannii, and K. pneumoniae. There was no effect of ciclopirox on biofilm production, suggesting it does not target Rcs. Altogether, our data suggest ciclopirox-mediated alteration of lipopolysaccharides stimulates enterobactin production and affects bacterial swarming.
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Affiliation(s)
- Zachary C. Conley
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kimberly M. Carlson-Banning
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ashley G. Carter
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Alejandro de la Cova
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Center for Environmental and Human Toxicology, University of Florida College of Veterinary Medicine, University of Florida, Gainesville, Florida, United States of America
| | - Yongcheng Song
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Lynn Zechiedrich
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Pharmacology and Chemical Biology, Baylor College of Medicine, Houston, Texas, United States of America
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Rousset F, Cui L, Siouve E, Becavin C, Depardieu F, Bikard D. Genome-wide CRISPR-dCas9 screens in E. coli identify essential genes and phage host factors. PLoS Genet 2018; 14:e1007749. [PMID: 30403660 PMCID: PMC6242692 DOI: 10.1371/journal.pgen.1007749] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 11/19/2018] [Accepted: 10/09/2018] [Indexed: 12/22/2022] Open
Abstract
High-throughput genetic screens are powerful methods to identify genes linked to a given phenotype. The catalytic null mutant of the Cas9 RNA-guided nuclease (dCas9) can be conveniently used to silence genes of interest in a method also known as CRISPRi. Here, we report a genome-wide CRISPR-dCas9 screen using a starting pool of ~ 92,000 sgRNAs which target random positions in the chromosome of E. coli. To benchmark our method, we first investigate its utility to predict gene essentiality in the genome of E. coli during growth in rich medium. We could identify 79% of the genes previously reported as essential and demonstrate the non-essentiality of some genes annotated as essential. In addition, we took advantage of the intermediate repression levels obtained when targeting the template strand of genes to show that cells are very sensitive to the expression level of a limited set of essential genes. Our data can be visualized on CRISPRbrowser, a custom web interface available at crispr.pasteur.fr. We then apply the screen to discover E. coli genes required by phages λ, T4 and 186 to kill their host, highlighting the involvement of diverse host pathways in the infection process of the three tested phages. We also identify colanic acid capsule synthesis as a shared resistance mechanism to all three phages. Finally, using a plasmid packaging system and a transduction assay, we identify genes required for the formation of functional λ capsids, thus covering the entire phage cycle. This study demonstrates the usefulness and convenience of pooled genome-wide CRISPR-dCas9 screens in bacteria and paves the way for their broader use as a powerful tool in bacterial genomics. Over the past few years, CRISPR-Cas technologies have emerged as powerful tools to edit genomes and modulate gene expression. They have been applied to perform high-throughput genetic screens with the purpose to understand the function of genes in a systematic manner, but the application of these screens to bacteria have so far remained limited. Here, we present the use of a library of ~92,000 guide RNAs directing the dCas9 protein to silence one by one all the genes in the chromosome of E. coli. To benchmark our method, we first investigate the performance of the technique to identify essential genes, highlighting several non-essential genes also found to be essential by other methods. We then apply our method to detect bacterial genes required by three different bacteriophages to kill E. coli and for the production of functional progeny by phage λ. Our screens highlight previously known and new genetic interactions between phages and their host’s pathways and emphasize the importance of bacterial capsule in the resistance to multiple phages. Altogether, our results demonstrate the usefulness of genome-wide CRISPR-dCas9 screens in bacteria to uncover genes involved in various phenotypes.
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Affiliation(s)
- François Rousset
- Synthetic Biology Group, Microbiology Department, Institut Pasteur, Paris, France
- Sorbonne Université, Collège Doctoral, Paris, France
| | - Lun Cui
- Synthetic Biology Group, Microbiology Department, Institut Pasteur, Paris, France
| | - Elise Siouve
- Synthetic Biology Group, Microbiology Department, Institut Pasteur, Paris, France
| | - Christophe Becavin
- Hub Bioinformatique et Biostatistique, Institut Pasteur - C3BI, USR 3756 IP CNRS, Paris, France
| | - Florence Depardieu
- Synthetic Biology Group, Microbiology Department, Institut Pasteur, Paris, France
| | - David Bikard
- Synthetic Biology Group, Microbiology Department, Institut Pasteur, Paris, France
- * E-mail:
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40
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Swarmer Cell Development of the Bacterium Proteus mirabilis Requires the Conserved Enterobacterial Common Antigen Biosynthesis Gene rffG. J Bacteriol 2018; 200:JB.00230-18. [PMID: 29967121 DOI: 10.1128/jb.00230-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Accepted: 06/27/2018] [Indexed: 01/01/2023] Open
Abstract
Individual cells of the bacterium Proteus mirabilis can elongate up to 40-fold on surfaces before engaging in a cooperative surface-based motility termed swarming. How cells regulate this dramatic morphological remodeling remains an open question. In this paper, we move forward the understanding of this regulation by demonstrating that P. mirabilis requires the gene rffG for swarmer cell elongation and subsequent swarm motility. The rffG gene encodes a protein homologous to the dTDP-glucose 4,6-dehydratase protein of Escherichia coli, which contributes to enterobacterial common antigen biosynthesis. Here, we characterize the rffG gene in P. mirabilis, demonstrating that it is required for the production of large lipopolysaccharide-linked moieties necessary for wild-type cell envelope integrity. We show that the absence of the rffG gene induces several stress response pathways, including those controlled by the transcriptional regulators RpoS, CaiF, and RcsB. We further show that in rffG-deficient cells, the suppression of the Rcs phosphorelay, via loss of RcsB, is sufficient to induce cell elongation and swarm motility. However, the loss of RcsB does not rescue cell envelope integrity defects and instead results in abnormally shaped cells, including cells producing more than two poles. We conclude that an RcsB-mediated response acts to suppress the emergence of shape defects in cell envelope-compromised cells, suggesting an additional role for RcsB in maintaining cell morphology under stress conditions. We further propose that the composition of the cell envelope acts as a checkpoint before cells initiate swarmer cell elongation and motility.IMPORTANCEProteus mirabilis swarm motility has been implicated in pathogenesis. We have found that cells deploy multiple uncharacterized strategies to handle cell envelope stress beyond the Rcs phosphorelay when attempting to engage in swarm motility. While RcsB is known to directly inhibit the master transcriptional regulator for swarming, we have shown an additional role for RcsB in protecting cell morphology. These data support a growing appreciation that the Rcs phosphorelay is a multifunctional regulator of cell morphology in addition to its role in microbial stress responses. These data also strengthen the paradigm that outer membrane composition is a crucial checkpoint for modulating entry into swarm motility. Furthermore, the rffG-dependent moieties provide a novel attractive target for potential antimicrobials.
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Nhu NTK, Phan MD, Peters KM, Lo AW, Forde BM, Min Chong T, Yin WF, Chan KG, Chromek M, Brauner A, Chapman MR, Beatson SA, Schembri MA. Discovery of New Genes Involved in Curli Production by a Uropathogenic Escherichia coli Strain from the Highly Virulent O45:K1:H7 Lineage. mBio 2018; 9:e01462-18. [PMID: 30131362 PMCID: PMC6106082 DOI: 10.1128/mbio.01462-18] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 07/10/2018] [Indexed: 11/20/2022] Open
Abstract
Curli are bacterial surface-associated amyloid fibers that bind to the dye Congo red (CR) and facilitate uropathogenic Escherichia coli (UPEC) biofilm formation and protection against host innate defenses. Here we sequenced the genome of the curli-producing UPEC pyelonephritis strain MS7163 and showed it belongs to the highly virulent O45:K1:H7 neonatal meningitis-associated clone. MS7163 produced curli at human physiological temperature, and this correlated with biofilm growth, resistance of sessile cells to the human cationic peptide cathelicidin, and enhanced colonization of the mouse bladder. We devised a forward genetic screen using CR staining as a proxy for curli production and identified 41 genes that were required for optimal CR binding, of which 19 genes were essential for curli synthesis. Ten of these genes were novel or poorly characterized with respect to curli synthesis and included genes involved in purine de novo biosynthesis, a regulator that controls the Rcs phosphorelay system, and a novel repressor of curli production (referred to as rcpA). The involvement of these genes in curli production was confirmed by the construction of defined mutants and their complementation. The mutants did not express the curli major subunit CsgA and failed to produce curli based on CR binding. Mutation of purF (the first gene in the purine biosynthesis pathway) and rcpA also led to attenuated colonization of the mouse bladder. Overall, this work has provided new insight into the regulation of curli and the role of these amyloid fibers in UPEC biofilm formation and pathogenesis.IMPORTANCE Uropathogenic Escherichia coli (UPEC) strains are the most common cause of urinary tract infection, a disease increasingly associated with escalating antibiotic resistance. UPEC strains possess multiple surface-associated factors that enable their colonization of the urinary tract, including fimbriae, curli, and autotransporters. Curli are extracellular amyloid fibers that enhance UPEC virulence and promote biofilm formation. Here we examined the function and regulation of curli in a UPEC pyelonephritis strain belonging to the highly virulent O45:K1:H7 neonatal meningitis-associated clone. Curli expression at human physiological temperature led to increased biofilm formation, resistance of sessile cells to the human cationic peptide LL-37, and enhanced bladder colonization. Using a comprehensive genetic screen, we identified multiple genes involved in curli production, including several that were novel or poorly characterized with respect to curli synthesis. In total, this study demonstrates an important role for curli as a UPEC virulence factor that promotes biofilm formation, resistance, and pathogenesis.
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Affiliation(s)
- Nguyen Thi Khanh Nhu
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
- Australian Centre for Ecogenomics, the University of Queensland, Brisbane, Queensland, Australia
| | - Minh-Duy Phan
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
| | - Kate M Peters
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
| | - Alvin W Lo
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
| | - Brian M Forde
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
- Australian Centre for Ecogenomics, the University of Queensland, Brisbane, Queensland, Australia
| | - Teik Min Chong
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Wai-Fong Yin
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Kok-Gan Chan
- Division of Genetics and Molecular Biology, Institute of Biological Sciences, Faculty of Sciences, University of Malaya, Kuala Lumpur, Malaysia
- International Genome Centre, Jiangsu University, Zhenjiang, China
| | - Milan Chromek
- Department of Microbiology, Tumor and Cell Biology, Division of Clinical Microbiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
- Department of Pediatrics, CLINTEC, Karolinska University Hospital and Karolinska Institutet, Stockholm, Sweden
| | - Annelie Brauner
- Department of Microbiology, Tumor and Cell Biology, Division of Clinical Microbiology, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Matthew R Chapman
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Scott A Beatson
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
- Australian Centre for Ecogenomics, the University of Queensland, Brisbane, Queensland, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, the University of Queensland, Brisbane, Queensland, Australia
- Australian Infectious Diseases Research Centre, the University of Queensland, Brisbane, Queensland, Australia
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Abstract
Biofilms are often described as protective shelters that preserve bacteria from hostile surroundings. However, biofilm bacteria are also exposed to various stresses and need to adjust to the heterogeneous physicochemical conditions prevailing within biofilms. In Gram-negative bacteria, such adaptations can result in modifications of the lipopolysaccharide, a major component of the outer membrane characterized by a highly dynamic structure responding to environmental changes. We previously showed that Gram-negative biofilm bacteria undergo an increase in lipid A palmitoylation mediated by the PagP enzyme, contributing to increased resistance to host defenses. Here we describe a regulatory pathway leading to transcriptional induction of pagP in response to specific conditions created in the biofilm environment. We show that pagP expression is induced via the Rcs envelope stress system independently of the Rcs phosphorelay cascade and that it requires the GadE auxiliary regulator. Moreover, we identify an increase in osmolarity (i.e., ionic stress) as a signal able to induce pagP expression in an RcsB-dependent manner. Consistently, we show that the biofilm is a hyperosmolar environment and that RcsB-dependent pagP induction can be dampened in the presence of an osmoprotectant. These results provide new insights into the adaptive mechanisms of bacterial differentiation in biofilm.IMPORTANCE The development of the dense bacterial communities called biofilms creates a highly heterogeneous environment in which bacteria are subjected to a variety of physicochemical stresses. We investigated the mechanisms of a widespread and biofilm-associated chemical modification of the lipopolysaccharide (LPS), a major component of all Gram-negative bacterial outer membranes. This modification corresponds to the incorporation, mediated by the enzyme PagP, of a palmitate chain into lipid A (palmitoylation) that reduces bacterial recognition by host immune responses. Using biochemical and genetic approaches, we demonstrate that a significant part of biofilm-associated lipid A palmitoylation is triggered upon induction of pagP transcription by the hyperosmolar biofilm environment. pagP induction is regulated by RcsB, the response regulator of the Rcs stress response pathway, and is not observed under planktonic conditions. Our report provides new insights into how physiological adaptations to local biofilm microenvironments can contribute to decreases in susceptibility to antimicrobial agents and host immune defenses.
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Discovery of Calcium as a Biofilm-Promoting Signal for Vibrio fischeri Reveals New Phenotypes and Underlying Regulatory Complexity. J Bacteriol 2018; 200:JB.00016-18. [PMID: 29463601 DOI: 10.1128/jb.00016-18] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 02/09/2018] [Indexed: 11/20/2022] Open
Abstract
Vibrio fischeri uses biofilm formation to promote symbiotic colonization of its squid host, Euprymna scolopes Control over biofilm formation is exerted at the level of transcription of the symbiosis polysaccharide (syp) locus by a complex set of two-component regulators. Biofilm formation can be induced by overproduction of the sensor kinase RscS, which requires the activities of the hybrid sensor kinase SypF and the response regulator SypG and is negatively regulated by the sensor kinase BinK. Here, we identify calcium as a signal that promotes biofilm formation by biofilm-competent strains under conditions in which biofilms are not typically observed (growth with shaking). This was true for RscS-overproducing cells as well as for strains in which only the negative regulator binK was deleted. The latter results provided, for the first time, an opportunity to induce and evaluate biofilm formation without regulator overexpression. Using these conditions, we determined that calcium induces both syp-dependent and bacterial cellulose synthesis (bcs)-dependent biofilms at the level of transcription of these loci. The calcium-induced biofilms were dependent on SypF, but SypF's Hpt domain was sufficient for biofilm formation. These data suggested the involvement of another sensor kinase(s) and led to the discovery that both RscS and a previously uncharacterized sensor kinase, HahK, functioned in this pathway. Together, the data presented here reveal both a new signal and biofilm phenotype produced by V. fischeri cells, the coordinate production of two polysaccharides involved in distinct biofilm behaviors, and a new regulator that contributes to control over these processes.IMPORTANCE Biofilms, or communities of surface-attached microorganisms adherent via a matrix that typically includes polysaccharides, are highly resistant to environmental stresses and are thus problematic in the clinic and important to study. Vibrio fischeri forms biofilms to colonize its symbiotic host, making this organism useful for studying biofilms. Biofilm formation depends on the syp polysaccharide locus and its regulators. Here, we identify a signal, calcium, that induces both SYP-PS and cellulose-dependent biofilms. We also identify a new syp regulator, the sensor kinase HahK, and discover a mutant phenotype for the sensor kinase RscS. This work thus reveals a specific biofilm-inducing signal that coordinately controls two polysaccharides, identifies a new regulator, and clarifies the regulatory control over biofilm formation by V. fischeri.
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Genome-wide identification of genes regulated by RcsA, RcsB, and RcsAB phosphorelay regulators in Klebsiella pneumoniae NTUH-K2044. Microb Pathog 2018; 123:36-41. [PMID: 29944890 DOI: 10.1016/j.micpath.2018.06.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 05/04/2018] [Accepted: 06/22/2018] [Indexed: 12/11/2022]
Abstract
Rcs phosphorelay system is a two-component signal transduction system, which can regulate the transcription of capsule polysaccharide and biofilm related genes in Enterobacteriaceae. In this study, microarray technology was used to investigate the overall genes regulated by RcsA, RcsB, and RcsAB and the regulation mechanism in Klebsiella pneumoniae, then COG analysis was performed to explore the functions of the differentially expressed genes. According to the microarray data result, a total of 45, 223 and 217 genes regulated by RcsA, RcsB, and RcsAB were screened. The result of COG analysis suggested that inorganic ion transport and metabolism related genes have a majority in RcsA regulating genes. Most of RcsB regulated genes were showed involved in energy production and conversion process. Besides Carbohydrate transport and metabolism genes were identified as the major components of the RcsAB regulated genes. 15 differentially expressed genes were confirmed by quantitative real-time PCR (RT-qPCR). The RT-qPCR results indicated that 13 genes consistent with microarray data. The results of this study provided important evidence for further research to investigate the influence of RcsA, RcsB, RcsAB regulators and further efforts to address the diseased caused by K.pneumoniae, such as pneumonia, bacteremia, and urinary tract infection.
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Abstract
RcsB, a response regulator of the FixJ/NarL family, is at the center of a complex network of regulatory inputs and outputs. Cell surface stress is sensed by an outer membrane lipoprotein, RcsF, which regulates interactions of the inner membrane protein IgaA, lifting negative regulation of a phosphorelay. In vivo evidence supports a pathway in which histidine kinase RcsC transfers phosphate to phosphotransfer protein RcsD, resulting in phosphorylation of RcsB. RcsB acts either alone or in combination with RcsA to positively regulate capsule synthesis and synthesis of small RNA (sRNA) RprA as well as other genes, and to negatively regulate motility. RcsB in combination with other FixJ/NarL auxiliary proteins regulates yet other functions, independent of RcsB phosphorylation. Proper expression of Rcs and its targets is critical for success of Escherichia coli commensal strains, for proper development of biofilm, and for virulence in some pathogens. New understanding of how the Rcs phosphorelay works provides insight into the flexibility of the two-component system paradigm.
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Affiliation(s)
- Erin Wall
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA; emails: , ,
| | - Nadim Majdalani
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA; emails: , ,
| | - Susan Gottesman
- Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland 20892, USA; emails: , ,
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Evidence for up and down regulation of 450 genes by rpoB12 (rif) mutation and their implications in complexity of transcription modulation in Escherichia coli. Microbiol Res 2018; 212-213:80-93. [PMID: 29853171 DOI: 10.1016/j.micres.2018.04.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 03/20/2018] [Accepted: 04/28/2018] [Indexed: 11/22/2022]
Abstract
Analyses of mutations in rpoB subunit of Escherichia coli that lead to resistance to rifampicin have been invaluable in providing insight into events during transcription continue to be discovered. Earlier we reported that rpoB12 suppresses over-expression of cps genes in Δlon mutant of E. coli, by interfering with the transcription of rcsA. Here we report Microarray based Transcriptome profile of Δlon and Δlon rpoB12 strains. The data analyses clearly reveal that rpoB12 mutation results in the differential expression of ∼450 genes. The transcription profiles of some of the genes namely, rcsA, gadE, csgD, bolA, ypdI, dnaJ, clpP, csrA and hdeA are significantly altered, particularly the genes implicated in virulence. Some of the phenotypic traits namely, biofilm formation, motility, curli synthesis and ability to withstand acidic stress in a lon+rpoB12 strain were assessed. The results clearly indicate that rpoB12 up-regulates biofilm formation and curli synthesis while it makes the cells sensitive for growth in acidic medium and inhibits motility almost completely. Furthermore, rpoB12 modulates the expression profile of a significant number of genes involved in stress responses, genes encoding small RNAs. Thus, this study reveals the versatile role of the rpoB12 mutation, especially its impact on the regulation of genes related to virulence and highlights its medical importance.
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Guo XP, Sun YC. New Insights into the Non-orthodox Two Component Rcs Phosphorelay System. Front Microbiol 2017; 8:2014. [PMID: 29089936 PMCID: PMC5651002 DOI: 10.3389/fmicb.2017.02014] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 09/29/2017] [Indexed: 01/18/2023] Open
Abstract
The Rcs phosphorelay system, a non-orthodox two-component regulatory system, integrates environmental signals, regulates gene expression, and alters the physiological behavior of members of the Enterobacteriaceae family of Gram-negative bacteria. Recent studies of Rcs system focused on protein interactions, functions, and the evolution of Rcs system components and its auxiliary regulatory proteins. Herein we review the latest advances on the Rcs system proteins, and discuss the roles that the Rcs system plays in the environmental adaptation of various Enterobacteriaceae species.
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Affiliation(s)
- Xiao-Peng Guo
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yi-Cheng Sun
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Major Tom to Ground Control: How Lipoproteins Communicate Extracytoplasmic Stress to the Decision Center of the Cell. J Bacteriol 2017; 199:JB.00216-17. [PMID: 28674071 DOI: 10.1128/jb.00216-17] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The envelope of bacteria is a complex multilayered shield that ensures multiple essential functions, including protecting the cell from external assaults. Hence, bacterial cells have evolved intricate mechanisms called envelope stress response systems (ESRS) to monitor all kinds of perturbations affecting the integrity of their envelope and to mount an appropriate response to contain or repair the damage. In the model bacterium Escherichia coli, several ESRS are built around a two-component system, in which envelope stress triggers a phosphotransfer between a sensor protein in the inner membrane of the envelope and a response regulator in the cytoplasm. In this review, we focus on two major ESRS in E. coli, the Rcs and Cpx pathways, in which additional proteins not directly involved in the phosphotransfer modulate signal transduction. Both the Rcs and Cpx systems can be turned on by a lipoprotein anchored in the outer membrane, RcsF and NlpE, respectively, providing a molecular connection between the most exterior layer of the envelope and the ground control center in the cytoplasm. Here, we review how these two lipoproteins, which share a striking set of features while being distinct in several aspects, act as sentinels at the front line of the bacterium by sensing and transducing stress to the downstream components of the Rcs and Cpx systems.
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Involvement of Two-Component Signaling on Bacterial Motility and Biofilm Development. J Bacteriol 2017; 199:JB.00259-17. [PMID: 28533218 DOI: 10.1128/jb.00259-17] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Two-component signaling is a specialized mechanism that bacteria use to respond to changes in their environment. Nonpathogenic strains of Escherichia coli K-12 harbor 30 histidine kinases and 32 response regulators, which form a network of regulation that integrates many other global regulators that do not follow the two-component signaling mechanism, as well as signals from central metabolism. The output of this network is a multitude of phenotypic changes in response to changes in the environment. Among these phenotypic changes, many two-component systems control motility and/or the formation of biofilm, sessile communities of bacteria that form on surfaces. Motility is the first reversible attachment phase of biofilm development, followed by a so-called swim or stick switch toward surface organelles that aid in the subsequent phases. In the mature biofilm, motility heterogeneity is generated by a combination of evolutionary and gene regulatory events.
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Bittner LM, Arends J, Narberhaus F. When, how and why? Regulated proteolysis by the essential FtsH protease in Escherichia coli. Biol Chem 2017; 398:625-635. [PMID: 28085670 DOI: 10.1515/hsz-2016-0302] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/09/2017] [Indexed: 11/15/2022]
Abstract
Cellular proteomes are dynamic and adjusted to permanently changing conditions by ATP-fueled proteolytic machineries. Among the five AAA+ proteases in Escherichia coli FtsH is the only essential and membrane-anchored metalloprotease. FtsH is a homohexamer that uses its ATPase domain to unfold and translocate substrates that are subsequently degraded without the need of ATP in the proteolytic chamber of the protease domain. FtsH eliminates misfolded proteins in the context of general quality control and properly folded proteins for regulatory reasons. Recent trapping approaches have revealed a number of novel FtsH substrates. This review summarizes the substrate diversity of FtsH and presents details on the surprisingly diverse recognition principles of three well-characterized substrates: LpxC, the key enzyme of lipopolysaccharide biosynthesis; RpoH, the alternative heat-shock sigma factor and YfgM, a bifunctional membrane protein implicated in periplasmic chaperone functions and cytoplasmic stress adaptation.
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Affiliation(s)
- Lisa-Marie Bittner
- Microbial Biology, Ruhr University Bochum, Universitätsstr. 150, NDEF 06/783, D-44801 Bochum
| | - Jan Arends
- Microbial Biology, Ruhr University Bochum, Universitätsstr. 150, NDEF 06/783, D-44801 Bochum
| | - Franz Narberhaus
- Microbial Biology, Ruhr University Bochum, Universitätsstr. 150, NDEF 06/783, D-44801 Bochum
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