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Liu C, Qian R, Shi W, Kou L, Wang J, Ma X, Ren H, Gao S, Ren J. EⅡB Mutation Reduces the Pathogenicity of Listeria monocytogenes by Negatively Regulating Biofilm Formation Ability, Infective Capacity, and Virulence Gene Expression. Vet Sci 2024; 11:301. [PMID: 39057985 PMCID: PMC11281496 DOI: 10.3390/vetsci11070301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Revised: 06/28/2024] [Accepted: 06/30/2024] [Indexed: 07/28/2024] Open
Abstract
To explore the role of the membrane permease ⅡB (EⅡB) gene of Listeria pathogenicity island 4 (LIPI-4) in the virulence of Listeria monocytogenes, both an EⅡB deletion strain (∆EⅡB) and a complemented strain were constructed. In vitro experiments demonstrated that EⅡB deletion affected the biofilm formation ability of the wild-type strain (Lm928). Moreover, this deletion decreased the intracellular proliferation abilities of L. monocytogenes. Mice infected with ∆EⅡB survived longer and experienced less weight loss on days 1, 2, and 3 post-infection. The bacterial load in the liver tissue of ∆EⅡB-infected mice was significantly reduced, and a considerable decrease in the blood levels of inflammatory cytokines IL-β, IL-6, IL-10, and TNF-α were observed. Following EⅡB deletion, 65% (13/20) of genes were downregulated, 25% (5/20) were upregulated, and 10% (2/20) showed no change. These findings suggest that EⅡB deletion may reduce both the in vivo and in vitro virulence levels as well as the biofilm formation ability of Lm928 by downregulating the transcription levels of genes associated with virulence and biofilm formation. These findings provide a foundation for further examining the pathogenic mechanisms of LIPI-4 and EⅡB in L. monocytogenes.
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Affiliation(s)
| | | | | | | | - Jing Wang
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China; (C.L.); (R.Q.); (W.S.); (L.K.); (H.R.); (S.G.); (J.R.)
| | - Xun Ma
- College of Animal Science and Technology, Shihezi University, Shihezi 832000, China; (C.L.); (R.Q.); (W.S.); (L.K.); (H.R.); (S.G.); (J.R.)
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2
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Chen M, Ren G, Zhang X, Yang L, Ding Q, Sun J, Xia J, Xu J, Jiang L, Fang W, Cheng C, Song H. DegU-mediated suppression of carbohydrate uptake in Listeria monocytogenes increases adaptation to oxidative stress. Appl Environ Microbiol 2023; 89:e0101723. [PMID: 37787570 PMCID: PMC10617591 DOI: 10.1128/aem.01017-23] [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: 06/19/2023] [Accepted: 08/11/2023] [Indexed: 10/04/2023] Open
Abstract
The foodborne bacterial pathogen Listeria monocytogenes exhibits remarkable survival capabilities under challenging conditions, severely threatening food safety and human health. The orphan regulator DegU is a pleiotropic regulator required for bacterial environmental adaptation. However, the specific mechanism of how DegU participates in oxidative stress tolerance remains unknown in L. monocytogenes. In this study, we demonstrate that DegU suppresses carbohydrate uptake under stress conditions by altering global transcriptional profiles, particularly by modulating the transcription of the phosphoenolpyruvate-carbohydrate phosphotransferase system (PTS)-related genes, such as ptsH, ptsI, and hprK. Specifically, in the absence of degU, the transcripts of ptsI are significantly upregulated and those of hprK are significantly downregulated in response to copper ion-induced stress. Overexpression of ptsI significantly increases bacterial growth in vitro, while overexpression of hprK leads to a decrease in growth. We further demonstrate that DegU directly senses oxidative stress, downregulates ptsI transcription, and upregulates hprK transcription. Additionally, through an electrophoretic mobility shift assay, we demonstrate that DegU directly regulates the transcription of ptsI and hprK by binding to specific regions within their respective promoter sequences. Notably, the putative pivotal DegU binding sequence for ptsI is located from 38 to 68 base pairs upstream of the ptsH transcription start site (TSS), whereas for hprK, it is mapped from 36 to 124 base pairs upstream of the hprK TSS. In summary, we elucidate that DegU plays a significant role in suppressing carbohydrate uptake in response to oxidative stress through the direct regulation of ptsI and hprK.ImportanceUnderstanding the adaptive mechanisms employed by Listeria monocytogenes in harsh environments is of great significance. This study focuses on investigating the role of DegU in response to oxidative stress by examining global transcriptional profiles. The results highlight the noteworthy involvement of DegU in this stress response. Specifically, DegU acts as a direct sensor of oxidative stress, leading to the modulation of gene transcription. It downregulates ptsI transcription while it upregulates hprK transcription through direct binding to their promoters. Consequently, these regulatory actions impede bacterial growth, providing a defense mechanism against stress-induced damage. These findings gained from this study may have broader implications, serving as a reference for studying adaptive mechanisms in other pathogenic bacteria and aiding in the development of targeted strategies to control L. monocytogenes and ensure food safety.
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Affiliation(s)
- Mianmian Chen
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Gengjia Ren
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Xian Zhang
- School of Medicine, Zhejiang University, Hangzhou, China
| | - Lifeng Yang
- Ningbo College of Health Sciences, Ningbo, China
| | - Qiang Ding
- Ningbo College of Health Sciences, Ningbo, China
| | - Jing Sun
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Jing Xia
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Jiali Xu
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Lingli Jiang
- Ningbo College of Health Sciences, Ningbo, China
| | - Weihuan Fang
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Changyong Cheng
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Houhui Song
- Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang Provincial Engineering Research Center for Animal Health Diagnostics & Advanced Technology, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- Zhejiang International Science and Technology Cooperation Base for Veterinary Medicine and Health Management, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
- China-Australia Joint Laboratory for Animal Health Big Data Analytics, College of Animal Science and Technology & College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
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3
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Fischer MA, Engelgeh T, Rothe P, Fuchs S, Thürmer A, Halbedel S. Listeria monocytogenes genes supporting growth under standard laboratory cultivation conditions and during macrophage infection. Genome Res 2022; 32:1711-1726. [PMID: 36114002 PMCID: PMC9528990 DOI: 10.1101/gr.276747.122] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 08/04/2022] [Indexed: 11/24/2022]
Abstract
The Gram-positive bacterium Listeria monocytogenes occurs widespread in the environment and infects humans when ingested along with contaminated food. Such infections are particularly dangerous for risk group patients, for whom they represent a life-threatening disease. To invent novel strategies to control contamination and disease, it is important to identify those cellular processes that maintain pathogen growth inside and outside the host. Here, we have applied transposon insertion sequencing (Tn-Seq) to L. monocytogenes for the identification of such processes on a genome-wide scale. Our approach identified 394 open reading frames that are required for growth under standard laboratory conditions and 42 further genes, which become necessary during intracellular growth in macrophages. Most of these genes encode components of the translation machinery and act in chromosome-related processes, cell division, and biosynthesis of the cellular envelope. Several cofactor biosynthesis pathways and 29 genes with unknown functions are also required for growth, suggesting novel options for the development of antilisterial drugs. Among the genes specifically required during intracellular growth are known virulence factors, genes compensating intracellular auxotrophies, and several cell division genes. Our experiments also highlight the importance of PASTA kinase signaling for general viability and of glycine metabolism and chromosome segregation for efficient intracellular growth of L. monocytogenes.
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Affiliation(s)
- Martin A Fischer
- FG11 Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, 38855 Wernigerode, Germany
| | - Tim Engelgeh
- FG11 Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, 38855 Wernigerode, Germany
| | - Patricia Rothe
- FG11 Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, 38855 Wernigerode, Germany
| | - Stephan Fuchs
- MF1 Bioinformatic Support, Robert Koch Institute, 13353 Berlin, Germany
| | - Andrea Thürmer
- MF2 Genome Sequencing, Robert Koch Institute, 13353 Berlin, Germany
| | - Sven Halbedel
- FG11 Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, 38855 Wernigerode, Germany
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4
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Wang M, Wang H, Wang P, Fu HH, Li CY, Qin QL, Liang Y, Wang M, Chen XL, Zhang YZ, Zhang W. TCA cycle enhancement and uptake of monomeric substrates support growth of marine Roseobacter at low temperature. Commun Biol 2022; 5:705. [PMID: 35835984 PMCID: PMC9283371 DOI: 10.1038/s42003-022-03631-2] [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: 11/15/2021] [Accepted: 06/24/2022] [Indexed: 11/29/2022] Open
Abstract
Members of the marine Roseobacter group are ubiquitous in global oceans, but their cold-adaptive strategies have barely been studied. Here, as represented by Loktanella salsilacus strains enriched in polar regions, we firstly characterized the metabolic features of a cold-adapted Roseobacter by multi-omics, enzyme activities, and carbon utilization procedures. Unlike in most cold-adapted microorganisms, the TCA cycle is enhanced by accumulating more enzyme molecules, whereas genes for thiosulfate oxidation, sulfate reduction, nitrate reduction, and urea metabolism are all expressed at lower abundance when L. salsilacus was growing at 5 °C in comparison with higher temperatures. Moreover, a carbon-source competition experiment has evidenced the preferential use of glucose rather than sucrose at low temperature. This selective utilization is likely to be controlled by the carbon source uptake and transformation steps, which also reflects an economic calculation balancing energy production and functional plasticity. These findings provide a mechanistic understanding of how a Roseobacter member and possibly others as well counteract polar constraints. The metabolic adaptation of Loktanella salsilacus strains to cold involves an increase of enzymes involved in the TCA cycle and preferential use of glucose rather than sucrose at low temperature, providing insights into how Roseobacter adapts in polar regions.
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Affiliation(s)
- Meng Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.,Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, 266003, China.,State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China
| | - Huan Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Peng Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Hui-Hui Fu
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Chun-Yang Li
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Qi-Long Qin
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.,State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China
| | - Yantao Liang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Min Wang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China
| | - Xiu-Lan Chen
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, 266373, China
| | - Yu-Zhong Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China. .,Frontiers Science Center for Deep Ocean Multispheres and Earth System, Ocean University of China, Qingdao, 266003, China. .,State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, 266237, China. .,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology, Qingdao, 266373, China.
| | - Weipeng Zhang
- College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
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5
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Structural and biochemical analyses of the flagellar expression regulator DegU from Listeria monocytogenes. Sci Rep 2022; 12:10856. [PMID: 35798759 PMCID: PMC9263151 DOI: 10.1038/s41598-022-14459-5] [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: 11/13/2021] [Accepted: 06/07/2022] [Indexed: 11/24/2022] Open
Abstract
Listeria monocytogenes is a pathogenic bacterium that produces flagella, the locomotory organelles, in a temperature-dependent manner. At 37 °C inside humans, L. monocytogenes employs MogR to repress the expression of flagellar proteins, thereby preventing the production of flagella. However, in the low-temperature environment outside of the host, the antirepressor GmaR inactivates MogR, allowing flagellar formation. Additionally, DegU is necessary for flagellar expression at low temperatures. DegU transcriptionally activates the expression of GmaR and flagellar proteins by binding the operator DNA in the fliN-gmaR promoter as a response regulator of a two-component regulatory system. To determine the DegU-mediated regulation mechanism, we performed structural and biochemical analyses on the recognition of operator DNA by DegU. The DegU-DNA interaction is primarily mediated by a C-terminal DNA-binding domain (DBD) and can be fortified by an N-terminal receiver domain (RD). The DegU DBD adopts a tetrahelical helix-turn-helix structure and assembles into a dimer. The DegU DBD dimer recognizes the operator DNA using a positive patch. Unexpectedly, unlike typical response regulators, DegU interacts with operator DNA in both unphosphorylated and phosphorylated states with similar binding affinities. Therefore, we conclude that DegU is a noncanonical response regulator that is constitutively active irrespective of phosphorylation.
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6
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Sévellec Y, Ascencio E, Douarre PE, Félix B, Gal L, Garmyn D, Guillier L, Piveteau P, Roussel S. Listeria monocytogenes: Investigation of Fitness in Soil Does Not Support the Relevance of Ecotypes. Front Microbiol 2022; 13:917588. [PMID: 35770178 PMCID: PMC9234652 DOI: 10.3389/fmicb.2022.917588] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Listeria monocytogenes (Lm) is a ubiquitous bacterium that causes the serious foodborne illness listeriosis. Although soil is a primary reservoir and a central habitat for Lm, little information is available on the genetic features underlying the fitness of Lm strains in this complex habitat. The aim of this study was to identify (i) correlations between the strains fitness in soil, their origin and their phylogenetic position (ii) identify genetic markers allowing Lm to survive in the soil. To this end, we assembled a balanced panel of 216 Lm strains isolated from three major ecological compartments (outdoor environment, animal hosts, and food) and from 33 clonal complexes occurring worldwide. The ability of the 216 strains to survive in soil was tested phenotypically. Hierarchical clustering identified three phenotypic groups according to the survival rate (SR): phenotype 1 “poor survivors” (SR < 2%), phenotype 2 “moderate survivors” (2% < SR < 5%) and phenotype 3 “good survivors” (SR > 5%). Survival in soil depended neither on strains’ origin nor on their phylogenetic position. Genome-wide-association studies demonstrated that a greater number of genes specifically associated with a good survival in soil was found in lineage II strains (57 genes) than in lineage I strains (28 genes). Soil fitness was mainly associated with variations in genes (i) coding membrane proteins, transcription regulators, and stress resistance genes in both lineages (ii) coding proteins related to motility and (iii) of the category “phage-related genes.” The cumulative effect of these small genomic variations resulted in significant increase of soil fitness.
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Affiliation(s)
- Yann Sévellec
- Maisons-Alfort Laboratory for Food Safety, Salmonella and Listeria Unit, University of Paris-Est, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), Maisons-Alfort, France
| | - Eliette Ascencio
- Agroecologie, AgroSup Dijon, INRAE, Bourgogne Franche-Comté University, Dijon, France
| | - Pierre-Emmanuel Douarre
- Maisons-Alfort Laboratory for Food Safety, Salmonella and Listeria Unit, University of Paris-Est, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), Maisons-Alfort, France
| | - Benjamin Félix
- Maisons-Alfort Laboratory for Food Safety, Salmonella and Listeria Unit, University of Paris-Est, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), Maisons-Alfort, France
| | - Laurent Gal
- Agroecologie, AgroSup Dijon, INRAE, Bourgogne Franche-Comté University, Dijon, France
| | - Dominique Garmyn
- Agroecologie, AgroSup Dijon, INRAE, Bourgogne Franche-Comté University, Dijon, France
| | - Laurent Guillier
- Risk Assessment Department, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), University of Paris-Est, Maisons-Alfort, France
| | | | - Sophie Roussel
- Maisons-Alfort Laboratory for Food Safety, Salmonella and Listeria Unit, University of Paris-Est, French Agency for Food, Environmental and Occupational Health and Safety (ANSES), Maisons-Alfort, France
- *Correspondence: Sophie Roussel,
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Abstract
Neisseria gonorrhoeae is an obligate human pathogen that is the cause of the sexually transmitted disease gonorrhoea. Recently, there has been a surge in gonorrhoea cases that has been exacerbated by the rapid rise in gonococcal multidrug resistance to all useful antimicrobials resulting in this organism becoming a significant public health burden. Therefore, there is a clear and present need to understand the organism's biology through its physiology and pathogenesis to help develop new intervention strategies. The gonococcus initially colonises and adheres to host mucosal surfaces utilising a type IV pilus that helps with microcolony formation. Other adhesion strategies include the porin, PorB, and the phase variable outer membrane protein Opa. The gonococcus is able to subvert complement mediated killing and opsonisation by sialylation of its lipooligosaccharide and deploys a series of anti-phagocytic mechanisms. N. gonorrhoeae is a fastidious organism that is able to grow on a limited number of primary carbon sources such as glucose and lactate. The utilization of lactate by the gonococcus has been implicated in a number of pathogenicity mechanisms. The bacterium lives mainly in microaerobic environments and can grow both aerobically and anaerobically with the aid of nitrite. The gonococcus does not produce siderophores for scavenging iron but can utilize some produced by other bacteria, and it is able to successful chelate iron from host haem, transferrin and lactoferrin. The gonococcus is an incredibly versatile human pathogen; in the following chapter, we detail the intricate mechanisms used by the bacterium to invade and survive within the host.
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Affiliation(s)
- Luke R Green
- Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Joby Cole
- Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Ernesto Feliz Diaz Parga
- Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom
| | - Jonathan G Shaw
- Department of Infection, Immunity & Cardiovascular Disease, University of Sheffield, Sheffield, United Kingdom.
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8
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Cheng C, Liu F, Jin H, Xu X, Xu J, Deng S, Xia J, Han Y, Lei L, Zhang X, Song H. The DegU Orphan Response Regulator Contributes to Heat Stress Resistance in Listeria monocytogenes. Front Cell Infect Microbiol 2021; 11:761335. [PMID: 34966695 PMCID: PMC8711649 DOI: 10.3389/fcimb.2021.761335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 11/25/2021] [Indexed: 11/24/2022] Open
Abstract
Listeria monocytogenes is more heat-resistant than most other non-spore-forming foodborne pathogens, posing a severe threat to food safety and human health, particularly during chilled food processing. The DegU orphan response regulator is known to control heat resistance in L. monocytogenes; however, the underlying regulatory mechanism is poorly understood. Here, we show that DegU contributes to L. monocytogenes exponential growth under mild heat-shock stress. We further demonstrate that DegU directly senses heat stress through autoregulation and upregulates the hrcA-grpE-dnaK-dnaJ operon, leading to increased production of heat-shock proteins. We also show that DegU can directly regulate the expression of the hrcA-grpE-dnaK-dnaJ operon. In conclusion, our results shed light on the regulatory mechanisms underlying how DegU directly activates the hrcA-grpE-dnaK-dnaJ operon, thereby regulating heat resistance in L. monocytogenes.
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Affiliation(s)
- Changyong Cheng
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Feng Liu
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Haobo Jin
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Xiangfei Xu
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Jiali Xu
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Simin Deng
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Jing Xia
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Yue Han
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Lei Lei
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Xian Zhang
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
| | - Houhui Song
- College of Animal Science and Technology & College of Veterinary Medicine of Zhejiang Agriculture and Forestry University, Key Laboratory of Applied Technology on Green-Eco-Healthy Animal Husbandry of Zhejiang Province, China-Australia Joint Laboratory for Animal Health Big Data Analytics, Zhejiang Provincial Engineering Laboratory for Animal Health Inspection & Internet Technology, Hangzhou, China
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9
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Ahn SJ, Desai S, Blanco L, Lin M, Rice KC. Acetate and Potassium Modulate the Stationary-Phase Activation of lrgAB in Streptococcus mutans. Front Microbiol 2020; 11:401. [PMID: 32231651 PMCID: PMC7082836 DOI: 10.3389/fmicb.2020.00401] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 02/26/2020] [Indexed: 12/28/2022] Open
Abstract
Fluctuating environments force bacteria to constantly adapt and optimize the uptake of substrates to maintain cellular and nutritional homeostasis. Our recent findings revealed that LrgAB functions as a pyruvate uptake system in Streptococcus mutans, and its activity is modulated in response to glucose and oxygen levels. Here, we show that the composition of the growth medium dramatically influences the magnitude and pattern of lrgAB activation. Specifically, tryptone (T) medium does not provide a preferred environment for stationary phase lrgAB activation, which is independent of external pyruvate concentration. The addition of pyruvate to T medium can elicit PlrgA activation during exponential growth, enabling the cell to utilize external pyruvate for improvement of cell growth. Through comparison of the medium composition and a series of GFP quantification assays for measurement of PlrgA activation, we found that acetate and potassium (K+) play important roles in eliciting PlrgA activation at stationary phase. Of note, supplementation of pooled human saliva to T medium induced lrgAB expression at stationary phase and in response to pyruvate, suggesting that LrgAB is likely functional in the oral cavity. High concentrations of acetate inhibit cell growth, while high concentrations of K+ negatively regulate lrgAB activation. qPCR analysis also revealed that growth in T medium (acetate/K+ limited) significantly affects the expression of genes related to the catabolic pathways of pyruvate, including the Pta/AckA pathway (acetate metabolism). Lastly, stationary phase lrgAB expression is not activated when S. mutans is cultured in T medium, even in a strain that overexpresses lytST. Taken together, these data suggest that lrgAB activation and pyruvate uptake in S. mutans are connected to acetate metabolism and potassium uptake systems, important for cellular and energy homeostasis. They also suggest that these factors need to be implemented when planning metabolic experiments and analyzing data in S. mutans studies that may be sensitive to stationary growth phase.
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Affiliation(s)
- Sang-Joon Ahn
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, United States
| | - Shailja Desai
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, United States
| | - Loraine Blanco
- Department of Biology, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL, United States
| | - Min Lin
- Department of Chemistry, College of Liberal Arts and Sciences, University of Florida, Gainesville, FL, United States
| | - Kelly C Rice
- Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL, United States
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10
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López-López N, Euba B, Hill J, Dhouib R, Caballero L, Leiva J, Hosmer J, Cuesta S, Ramos-Vivas J, Díez-Martínez R, Schirra HJ, Blank LM, Kappler U, Garmendia J. Haemophilus influenzae Glucose Catabolism Leading to Production of the Immunometabolite Acetate Has a Key Contribution to the Host Airway-Pathogen Interplay. ACS Infect Dis 2020; 6:406-421. [PMID: 31933358 DOI: 10.1021/acsinfecdis.9b00359] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Chronic obstructive pulmonary disease (COPD) is characterized by abnormal inflammatory responses and impaired airway immunity, which provides an opportunistic platform for nontypeable Haemophilus influenzae (NTHi) infection. Clinical evidence supports that the COPD airways present increased concentrations of glucose, which may facilitate proliferation of pathogenic bacteria able to use glucose as a carbon source. NTHi metabolizes glucose through respiration-assisted fermentation, leading to the excretion of acetate, formate, and succinate. We hypothesized that such specialized glucose catabolism may be a pathoadaptive trait playing a pivotal role in the NTHi airway infection. To find out whether this is true, we engineered and characterized bacterial mutant strains impaired to produce acetate, formate, or succinate by inactivating the ackA, pflA, and frdA genes, respectively. While the inactivation of the pflA and frdA genes only had minimal physiological effects, the inactivation of the ackA gene affected acetate production and led to reduced bacterial growth, production of lactate under low oxygen tension, and bacterial attenuation in vivo. Moreover, bacterially produced acetate was able to stimulate the expression of inflammatory genes by cultured airway epithelial cells. These results back the notion that the COPD lung supports NTHi growth on glucose, enabling production of fermentative end products acting as immunometabolites at the site of infection. Thus, glucose catabolism may contribute not only to NTHi growth but also to bacterially driven airway inflammation. This information has important implications for developing nonantibiotic antimicrobials, given that airway glucose homeostasis modifying drugs could help prevent microbial infections associated with chronic lung disease.
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Affiliation(s)
| | - Begoña Euba
- Instituto de Agrobiotecnologı́a, CSIC-Gobierno Navarra, 31192 Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Julian Hill
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Rabeb Dhouib
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Lucı́a Caballero
- Instituto de Agrobiotecnologı́a, CSIC-Gobierno Navarra, 31192 Mutilva, Spain
| | - José Leiva
- Servicio de Microbiologı́a, Clı́nica Universidad de Navarra, 31008 Pamplona, Spain
- Instituto de Investigación Sanitaria de Navarra (IdiSNA), 31008 Pamplona, Spain
| | - Jennifer Hosmer
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Sergio Cuesta
- Instituto de Agrobiotecnologı́a, CSIC-Gobierno Navarra, 31192 Mutilva, Spain
| | - José Ramos-Vivas
- Servicio Microbiologı́a, Hospital Universitario Marqués de Valdecilla and Instituto de Investigación Marqués de Valdecilla (IDIVAL), 39011 Santander, Spain
- Red Española de Investigación en Patologı́a Infecciosa (REIPI), ISCIII, Madrid, Spain
| | - Roberto Díez-Martínez
- Telum Therapeutics, Centro Europeo de Empresas e Innovación de Navarra (CEIN), 31110 Noáin, Spain
| | - Horst Joachim Schirra
- Centre for Advanced Imaging, The University of Queensland, 4072 St Lucia, Queensland, Australia
| | - Lars M. Blank
- Institute of Applied Biotechnology, RWTH Aachen University, 52074 Aachen, Germany
| | - Ulrike Kappler
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
| | - Junkal Garmendia
- Instituto de Agrobiotecnologı́a, CSIC-Gobierno Navarra, 31192 Mutilva, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
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11
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Liu Y, Feng H, Fu R, Zhang N, Du W, Shen Q, Zhang R. Induced root-secreted D-galactose functions as a chemoattractant and enhances the biofilm formation of Bacillus velezensis SQR9 in an McpA-dependent manner. Appl Microbiol Biotechnol 2019; 104:785-797. [PMID: 31813049 DOI: 10.1007/s00253-019-10265-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/09/2019] [Accepted: 11/22/2019] [Indexed: 12/26/2022]
Abstract
Chemotaxis towards root exudates and subsequent biofilm formation are very important for root colonization and for providing the beneficial functions of plant growth-promoting rhizobacteria (PGPRs). In this study, in comparison with other root-secreted compounds, D-galactose in the root exudates of cucumber was found to be a strong chemoattractant at the concentration of 1 μM for Bacillus velezensis SQR9. Chemotaxis assays with methyl-accepting chemotaxis proteins (MCPs) deletion strains demonstrated that McpA was solely responsible for chemotaxis towards D-galactose. Interestingly, D-galactose significantly enhanced the biofilm formation of SQR9 in an McpA-dependent manner. Further experiment showed that D-galactose also enhanced root colonization by SQR9. In addition, the secretion of D-galactose by cucumber roots could be induced by inoculation with SQR9, indicating that D-galactose may be an important signal in the interaction between plant and SQR9. These findings suggested that the root-secreted D-galactose was a signal, the secretion of which was induced by the beneficial bacteria, and which in turn induced colonization of the bacteria.
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Affiliation(s)
- Yunpeng Liu
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China
| | - Haichao Feng
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Ruixin Fu
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Nan Zhang
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Wenbin Du
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, People's Republic of China
| | - Qirong Shen
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Ruifu Zhang
- Key Laboratory of Microbial Resources Collection and Preservation, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing, 100081, People's Republic of China.
- Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, National Engineering Research Center for Organic-based Fertilizers, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
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12
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Tiensuu T, Guerreiro DN, Oliveira AH, O’Byrne C, Johansson J. Flick of a switch: regulatory mechanisms allowing Listeria monocytogenes to transition from a saprophyte to a killer. Microbiology (Reading) 2019; 165:819-833. [DOI: 10.1099/mic.0.000808] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Teresa Tiensuu
- Department of Molecular Biology; Molecular Infection Medicine, Sweden (MIMS); Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Duarte N. Guerreiro
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland Galway, Galway H91 TK33, Ireland
| | - Ana H. Oliveira
- Department of Molecular Biology; Molecular Infection Medicine, Sweden (MIMS); Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Conor O’Byrne
- Bacterial Stress Response Group, Microbiology, School of Natural Sciences, National University of Ireland Galway, Galway H91 TK33, Ireland
| | - Jörgen Johansson
- Department of Molecular Biology; Molecular Infection Medicine, Sweden (MIMS); Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
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13
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Johansson J, Freitag NE. Regulation of Listeria monocytogenes Virulence. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0064-2019. [PMID: 31441398 PMCID: PMC10957223 DOI: 10.1128/microbiolspec.gpp3-0064-2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Indexed: 02/07/2023] Open
Abstract
Whereas obligate human and animal bacterial pathogens may be able to depend upon the warmth and relative stability of their chosen replication niche, environmental bacteria such as Listeria monocytogenes that harbor the ability to replicate both within animal cells and in the outside environment must maintain the capability to manage life under a variety of disparate conditions. Bacterial life in the outside environment requires adaptation to wide ranges of temperature, available nutrients, and physical stresses such as changes in pH and osmolarity as well as desiccation. Following ingestion by a susceptible animal host, the bacterium must adapt to similar changes during transit through the gastrointestinal tract and overcome a variety of barriers associated with host innate immune responses. Rapid alteration of patterns of gene expression and protein synthesis represent one strategy for quickly adapting to a dynamic host landscape. Here, we provide an overview of the impressive variety of strategies employed by the soil-dwelling, foodborne, mammalian pathogen L. monocytogenes to straddle diverse environments and optimize bacterial fitness both inside and outside host cells.
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Affiliation(s)
- Jörgen Johansson
- Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden (MIMS) and Umeå Centre for Microbial Research (UCMR), Umeå University, 90187 Umeå, Sweden
| | - Nancy E Freitag
- Department of Microbiology and Immunology, University of Illinois at Chicago, Chicago IL
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14
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Lanciotti R, Braschi G, Patrignani F, Gobbetti M, De Angelis M. How Listeria monocytogenes Shapes Its Proteome in Response to Natural Antimicrobial Compounds. Front Microbiol 2019; 10:437. [PMID: 30930865 PMCID: PMC6423498 DOI: 10.3389/fmicb.2019.00437] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 02/20/2019] [Indexed: 12/19/2022] Open
Abstract
The goal of this study was to investigate the adaptation of L. monocytogenes Scott A cells to treatments with sublethal doses of antimicrobials (ethanol, citral, carvacrol, E-2-hexenal and thyme essential oil). The survival of L. monocytogenes cells was not affected by the antimicrobials at the concentrations assayed, with the exception of ethanol (1% v/v) and thyme essential oil (100 mg/L), which decreased cell viability from 8.53 ± 0.36 to 7.20 ± 0.22 log CFU/mL (P = 0.04). We subsequently evaluated how L. monocytogenes regulates and shapes its proteome in response to antimicrobial compounds. Compared to the control cells grown under optimal conditions, L. monocytogenes treated for 1 h with the antimicrobial compounds showed increased or decreased (≥ or ≤2-fold, respectively, P < 0.05) levels of protein synthesis for 223 protein spots. As shown multivariate clustering analysis, the proteome profiles differed between treatments. Adaptation and shaping of proteomes mainly concerned cell cycle control, cell division, chromosome, motility and regulatory related proteins, carbohydrate, pyruvate, nucleotide and nitrogen metabolism, cofactors and vitamins and stress response with contrasting responses for different stresses. Ethanol, citral (85 mg/l) or (E)-2-hexenal (150 mg/L) adapted cells increased survival during acid stress imposed under model (BHI) and food-like systems.
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Affiliation(s)
- Rosalba Lanciotti
- Dipartmento di Scienze e Tecnologie Agro-Alimentari, Università degli Studi di Bologna, Bologna, Italy
| | - Giacomo Braschi
- Dipartmento di Scienze e Tecnologie Agro-Alimentari, Università degli Studi di Bologna, Bologna, Italy
| | - Francesca Patrignani
- Dipartmento di Scienze e Tecnologie Agro-Alimentari, Università degli Studi di Bologna, Bologna, Italy
| | | | - Maria De Angelis
- Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università di Bari Aldo Moro, Bari, Italy
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15
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Duport C, Jobin M, Schmitt P. Adaptation in Bacillus cereus: From Stress to Disease. Front Microbiol 2016; 7:1550. [PMID: 27757102 PMCID: PMC5047918 DOI: 10.3389/fmicb.2016.01550] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 09/15/2016] [Indexed: 12/23/2022] Open
Abstract
Bacillus cereus is a food-borne pathogen that causes diarrheal disease in humans. After ingestion, B. cereus experiences in the human gastro-intestinal tract abiotic physical variables encountered in food, such as acidic pH in the stomach and changing oxygen conditions in the human intestine. B. cereus responds to environmental changing conditions (stress) by reversibly adjusting its physiology to maximize resource utilization while maintaining structural and genetic integrity by repairing and minimizing damage to cellular infrastructure. As reviewed in this article, B. cereus adapts to acidic pH and changing oxygen conditions through diverse regulatory mechanisms and then exploits its metabolic flexibility to grow and produce enterotoxins. We then focus on the intricate link between metabolism, redox homeostasis, and enterotoxins, which are recognized as important contributors of food-borne disease.
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Affiliation(s)
- Catherine Duport
- Sécurité et Qualité des Produits d'Origine Végétale, UMR0408, Avignon Université, Institut National de la Recherche Agronomique Avignon, France
| | - Michel Jobin
- Sécurité et Qualité des Produits d'Origine Végétale, UMR0408, Avignon Université, Institut National de la Recherche Agronomique Avignon, France
| | - Philippe Schmitt
- Sécurité et Qualité des Produits d'Origine Végétale, UMR0408, Avignon Université, Institut National de la Recherche Agronomique Avignon, France
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16
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Listeria monocytogenes σH Contributes to Expression of Competence Genes and Intracellular Growth. J Bacteriol 2016; 198:1207-17. [PMID: 26833412 DOI: 10.1128/jb.00718-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 01/26/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The alternative sigma factor σ(H)has two functions in Gram-positive bacteria: it regulates sporulation and the development of genetic competence. Listeria monocytogenes is a nonsporulating species in which competence has not yet been detected. Nevertheless, the main competence regulators and a series of orthologous genes that form the competence machinery are present in its genome; some of the competence genes play a role in optimal phagosomal escape. In this study, strains overexpressing σ(H) and strains with a σ(H) deletion were used to elucidate the contribution of σ(H) to the expression of the competence machinery genes inL. monocytogenes Gene expression analysis showed that σ(H) is, indeed, involved in comG and come regulation. Unexpectedly, we observed a unique regulation scheme in which σ(H) and the transcription factor ComK were involved. Population-level analysis showed that even with the overexpression of both factors, only a fraction of the cells expressed the competence machinery genes. Although we could not detect competence, σ(H) was crucial for phagosomal escape, which implies that this alternative sigma factor has specifically evolved to regulate the L. monocytogenes intracellular life cycle. IMPORTANCE Listeria monocytogenes can be an intracellular pathogen capable of causing serious infections in humans and animal species. Recently, the competence machinery genes were described as being necessary for optimal phagosomal escape, in which the transcription factor ComK plays an important role. On the other hand, our previous phylogenetic analysis suggested that the alternative sigma factor σ(H) might play a role in the regulation of competence genes. The present study shows that some of the competence genes belong to the σ(H) regulon and, importantly, that σ(H) is essential for intracellular growth, implying a unique physiological role of σ(H) among Firmicutes.
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17
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NH125 kills methicillin-resistant Staphylococcus aureus persisters by lipid bilayer disruption. Future Med Chem 2016; 8:257-69. [PMID: 26910612 DOI: 10.4155/fmc.15.189] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND NH125, a known WalK inhibitor kills MRSA persisters. However, its precise mode of action is still unknown. METHODS & RESULTS The mode of action of NH125 was investigated by comparing its spectrum of antimicrobial activity and its effects on membrane permeability and giant unilamellar vesicles (GUVs) with walrycin B, a WalR inhibitor and benzyldimethylhexadecylammonium chloride (16-BAC), a cationic surfactant. NH125 killed persister cells of a variety of Staphylococcus aureus strains. Similar to 16-BAC, NH125 killed MRSA persisters by inducing rapid membrane permeabilization and caused the rupture of GUVs, whereas walrycin B did not kill MRSA persisters or induce membrane permeabilization and did not affect GUVs. CONCLUSION NH125 kills MRSA persisters by interacting with and disrupting membranes in a detergent-like manner.
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18
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Acetate Dissimilation and Assimilation in Mycobacterium tuberculosis Depend on Carbon Availability. J Bacteriol 2015. [PMID: 26216844 DOI: 10.1128/jb.00259-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
UNLABELLED Mycobacterium tuberculosis persists inside granulomas in the human lung. Analysis of the metabolic composition of granulomas from guinea pigs revealed that one of the organic acids accumulating in the course of infection is acetate (B. S. Somashekar, A. G. Amin, C. D. Rithner, J. Troudt, R. Basaraba, A. Izzo, D. C. Crick, and D. Chatterjee, J Proteome Res 10:4186-4195, 2011, doi:http://dx.doi.org/10.1021/pr2003352), which might result either from metabolism of the pathogen or might be provided by the host itself. Our studies characterize a metabolic pathway by which M. tuberculosis generates acetate in the cause of fatty acid catabolism. The acetate formation depends on the enzymatic activities of Pta and AckA. Using actyl coenzyme A (acetyl-CoA) as a substrate, acetyl-phosphate is generated and finally dephosphorylated to acetate, which is secreted into the medium. Knockout mutants lacking either the pta or ackA gene showed significantly reduced acetate production when grown on fatty acids. This effect is even more pronounced when the glyoxylate shunt is blocked, resulting in higher acetate levels released to the medium. The secretion of acetate was followed by an assimilation of the metabolite when other carbon substrates became limiting. Our data indicate that during acetate assimilation, the Pta-AckA pathway acts in concert with another enzymatic reaction, namely, the acetyl-CoA synthetase (Acs) reaction. Thus, acetate metabolism might possess a dual function, mediating an overflow reaction to release excess carbon units and resumption of acetate as a carbon substrate. IMPORTANCE During infection, host-derived lipid components present the major carbon source at the infection site. β-Oxidation of fatty acids results in the formation of acetyl-CoA. In this study, we demonstrate that consumption of fatty acids by Mycobacterium tuberculosis activates an overflow mechanism, causing the pathogen to release excess carbon intermediates as acetate. The Pta-AckA pathway mediating acetate formation proved to be reversible, enabling M. tuberculosis to reutilize the previously secreted acetate as a carbon substrate for metabolism.
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Abstract
For a generation of microbiologists who study pathogenesis in the context of the human microbiome, understanding the diversity of bacterial metabolism is essential. In this chapter, I briefly describe how and why I became, and remain, interested in metabolism. I then will describe and compare some of the strategies used by bacteria to consume sugars as one example of metabolic diversity. I will end with a plea to embrace metabolism in the endeavor to understand pathogenesis.
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Affiliation(s)
- Alan J Wolfe
- Department of Microbiology and Immunology, Stritch School of Medicine, Health Sciences Division, Loyola University Chicago, Maywood, Illinois
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20
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Genetics and Physiology of Acetate Metabolism by the Pta-Ack Pathway of Streptococcus mutans. Appl Environ Microbiol 2015; 81:5015-25. [PMID: 25979891 DOI: 10.1128/aem.01160-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 05/12/2015] [Indexed: 12/24/2022] Open
Abstract
In the dental caries pathogen Streptococcus mutans, phosphotransacetylase (Pta) catalyzes the conversion of acetyl coenzyme A (acetyl-CoA) to acetyl phosphate (AcP), which can be converted to acetate by acetate kinase (Ack), with the concomitant generation of ATP. A ΔackA mutant displayed enhanced accumulation of AcP under aerobic conditions, whereas little or no AcP was observed in the Δpta or Δpta ΔackA mutant. The Δpta and Δpta ΔackA mutants also had diminished ATP pools compared to the size of the ATP pool for the parental or ΔackA strain. Surprisingly, when exposed to oxidative stress, the Δpta ΔackA strain appeared to regain the capacity to produce AcP, with a concurrent increase in the size of the ATP pool compared to that for the parental strain. The ΔackA and Δpta ΔackA mutants exhibited enhanced (p)ppGpp accumulation, whereas the strain lacking Pta produced less (p)ppGpp than the wild-type strain. The ΔackA and Δpta ΔackA mutants displayed global changes in gene expression, as assessed by microarrays. All strains lacking Pta, which had defects in AcP production under aerobic conditions, were impaired in their abilities to form biofilms when glucose was the growth carbohydrate. Collectively, these data demonstrate the complex regulation of the Pta-Ack pathway and critical roles for these enzymes in processes that appear to be essential for the persistence and pathogenesis of S. mutans.
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Biochemical and Kinetic Characterization of the Eukaryotic Phosphotransacetylase Class IIa Enzyme from Phytophthora ramorum. EUKARYOTIC CELL 2015; 14:652-60. [PMID: 25956919 DOI: 10.1128/ec.00007-15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 05/06/2015] [Indexed: 11/20/2022]
Abstract
Phosphotransacetylase (Pta), a key enzyme in bacterial metabolism, catalyzes the reversible transfer of an acetyl group from acetyl phosphate to coenzyme A (CoA) to produce acetyl-CoA and Pi. Two classes of Pta have been identified based on the absence (Pta(I)) or presence (Pta(II)) of an N-terminal regulatory domain. Pta(I) has been fairly well studied in bacteria and one genus of archaea; however, only the Escherichia coli and Salmonella enterica Pta(II) enzymes have been biochemically characterized, and they are allosterically regulated. Here, we describe the first biochemical and kinetic characterization of a eukaryotic Pta from the oomycete Phytophthora ramorum. The two Ptas from P. ramorum, designated PrPta(II)1 and PrPta(II)2, both belong to class II. PrPta(II)1 displayed positive cooperativity for both acetyl phosphate and CoA and is allosterically regulated. We compared the effects of different metabolites on PrPta(II)1 and the S. enterica Pta(II) and found that, although the N-terminal regulatory domains share only 19% identity, both enzymes are inhibited by ATP, NADP, NADH, phosphoenolpyruvate (PEP), and pyruvate in the acetyl-CoA/Pi-forming direction but are differentially regulated by AMP. Phylogenetic analysis of bacterial, archaeal, and eukaryotic sequences identified four subtypes of Pta(II) based on the presence or absence of the P-loop and DRTGG subdomains within the N-terminal regulatory domain. Although the E. coli, S. enterica, and P. ramorum enzymes all belong to the IIa subclass, our kinetic analysis has indicated that enzymes within a subclass can still display differences in their allosteric regulation.
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22
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Cairns LS, Martyn JE, Bromley K, Stanley-Wall NR. An alternate route to phosphorylating DegU of Bacillus subtilis using acetyl phosphate. BMC Microbiol 2015; 15:78. [PMID: 25887289 PMCID: PMC4404196 DOI: 10.1186/s12866-015-0410-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Accepted: 03/12/2015] [Indexed: 11/21/2022] Open
Abstract
Background Two-component signal transduction pathways allow bacteria to sense and respond to the environment. Typically such pathways comprise a sensor histidine kinase and a response regulator. Phosphorylation of the response regulator commonly results in its activation, allowing the protein to bind to target promoter elements to regulate transcription. Several mechanisms are used to prevent inappropriate phosphorylation of the response regulator, thereby ensuring a specific response. In Bacillus subtilis, the DegS-DegU two-component system controls transcription of target genes in a manner dependent on the level of the phosphorylated response regulator, DegU. Previous work has tentatively indicated that DegU, and DegU H12L, a DegU variant which displays enhanced stability of the phosphoryl moiety, can be phosphorylated in the absence of the kinase, DegS. Results The data presented here reveal that DegU H12L requires aspartic acid 56 (D56), the identified DegU phosphorylation site, for its activity. By indirectly measuring the level of DegU ~ P in the cell by assessment of several well recognised DegU regulated processes it was shown that DegU H12L retains its activity in the absence of DegS, and that mutation of D56 produced an inactive protein. Further experiments designed to raise the level of acetyl phosphate within the cell suggest that DegU can be phosphorylated by acetyl phosphate in the absence of degS. Additionally, the phenotypic and biochemical experiments presented indicate that DegU H12L can reliably mimic high levels of phosphorylated DegU. Conclusions The ability of acetyl phosphate to modify DegU, and indeed DegU H12L, reveal an additional layer of regulation for DegU phosphorylation that will be relevant when the level of DegS is low or in the absence of degS. Given the number of processes that DegU can activate or inhibit, extensive regulation at a number of levels is required to ensure that the system is not inappropriately stimulated. DegS has both kinase and phosphatase activity and our findings demonstrate that the phosphatase activity of DegS is essential to control the level of DegU phosphate. Overall we contribute to our understanding of how the intricate signalling pathway DegS-DegU is regulated in B. subtilis.
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Affiliation(s)
- Lynne S Cairns
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK. .,Current address: Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA, 02111, USA.
| | - Jessica E Martyn
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK. .,Current address: Sir William Dunn School of Pathology, South Parks Road Oxford, Oxford University, Oxford, OX1 3RE, UK.
| | - Keith Bromley
- James Clerk Maxwell Building, School of Physics, University of Edinburgh, Edinburgh, EH9 3JZ, UK.
| | - Nicola R Stanley-Wall
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.
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Marx P, Meiers M, Brückner R. Activity of the response regulator CiaR in mutants of Streptococcus pneumoniae R6 altered in acetyl phosphate production. Front Microbiol 2015; 5:772. [PMID: 25642214 PMCID: PMC4295557 DOI: 10.3389/fmicb.2014.00772] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Accepted: 12/17/2014] [Indexed: 11/25/2022] Open
Abstract
The two-component regulatory system (TCS) CiaRH of Streptococcus pneumoniae is implicated in competence, ß-lactam resistance, maintenance of cell integrity, bacteriocin production, host colonization, and virulence. Depending on the growth conditions, CiaR can be highly active in the absence of its cognate kinase CiaH, although phosphorylation of CiaR is required for DNA binding and gene regulation. To test the possibility that acetyl phosphate (AcP) could be the alternative phosphodonor, genes involved in pyruvate metabolism were disrupted to alter cellular levels of acetyl phosphate. Inactivating the genes of pyruvate oxidase SpxB, phosphotransacetylase Pta, and acetate kinase AckA, resulted in very low AcP levels and in strongly reduced CiaR-mediated gene expression in CiaH-deficient strains. Therefore, alternative phosphorylation of CiaR appears to proceed via AcP. The AcP effect on CiaR is not detected in strains with CiaH. Attempts to obtain elevated AcP by preventing its degradation by acetate kinase AckA, were not successful in CiaH-deficient strains with a functional SpxB, the most important enzyme for AcP production in S. pneumoniae. The ciaH-spxB-ackA mutant producing intermediate amounts of AcP could be constructed and showed a promoter activation, which was much higher than expected. Since activation was dependent on AcP, it can apparently be used more efficiently for CiaR phosphorylation in the absence of AckA. Therefore, high AcP levels in the absence of CiaH and AckA may cause extreme overexpression of the CiaR regulon leading to synthetic lethality. AckA is also involved in a regulatory response, which is mediated by CiaH. Addition of acetate to the growth medium switch CiaH from kinase to phosphatase. This switch is lost in the absence of AckA indicating metabolism of acetate is required, which starts with the production of AcP by AckA. Therefore, AckA plays a special regulatory role in the control of the CiaRH TCS.
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Affiliation(s)
- Patrick Marx
- Department of Microbiology, University of Kaiserslautern Kaiserslautern, Germany
| | - Marina Meiers
- Department of Microbiology, University of Kaiserslautern Kaiserslautern, Germany
| | - Reinhold Brückner
- Department of Microbiology, University of Kaiserslautern Kaiserslautern, Germany
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Listeria monocytogenes is resistant to lysozyme through the regulation, not the acquisition, of cell wall-modifying enzymes. J Bacteriol 2014; 196:3756-67. [PMID: 25157076 DOI: 10.1128/jb.02053-14] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Listeria monocytogenes is a Gram-positive facultative intracellular pathogen that is highly resistant to lysozyme, a ubiquitous enzyme of the innate immune system that degrades cell wall peptidoglycan. Two peptidoglycan-modifying enzymes, PgdA and OatA, confer lysozyme resistance on L. monocytogenes; however, these enzymes are also conserved among lysozyme-sensitive nonpathogens. We sought to identify additional factors responsible for lysozyme resistance in L. monocytogenes. A forward genetic screen for lysozyme-sensitive mutants led to the identification of 174 transposon insertion mutations that mapped to 13 individual genes. Four mutants were killed exclusively by lysozyme and not other cell wall-targeting molecules, including the peptidoglycan deacetylase encoded by pgdA, the putative carboxypeptidase encoded by pbpX, the orphan response regulator encoded by degU, and the highly abundant noncoding RNA encoded by rli31. Both degU and rli31 mutants had reduced expression of pbpX and pgdA, yet DegU and Rli31 did not regulate each other. Since pbpX and pgdA are also present in lysozyme-sensitive bacteria, this suggested that the acquisition of novel enzymes was not responsible for lysozyme resistance, but rather, the regulation of conserved enzymes by DegU and Rli31 conferred high lysozyme resistance. Each lysozyme-sensitive mutant exhibited attenuated virulence in mice, and a time course of infection revealed that the most lysozyme-sensitive strain was killed within 30 min of intravenous infection, a phenotype that was recapitulated in purified blood. Collectively, these data indicate that the genes required for lysozyme resistance are highly upregulated determinants of L. monocytogenes pathogenesis that are required for avoiding the enzymatic activity of lysozyme in the blood.
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Fonseca MV, Swanson MS. Nutrient salvaging and metabolism by the intracellular pathogen Legionella pneumophila. Front Cell Infect Microbiol 2014; 4:12. [PMID: 24575391 PMCID: PMC3920079 DOI: 10.3389/fcimb.2014.00012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Accepted: 01/23/2014] [Indexed: 11/13/2022] Open
Abstract
The Gram-negative bacterium Legionella pneumophila is ubiquitous in freshwater environments as a free-swimming organism, resident of biofilms, or parasite of protozoa. If the bacterium is aerosolized and inhaled by a susceptible human host, it can infect alveolar macrophages and cause a severe pneumonia known as Legionnaires' disease. A sophisticated cell differentiation program equips L. pneumophila to persist in both extracellular and intracellular niches. During its life cycle, L. pneumophila alternates between at least two distinct forms: a transmissive form equipped to infect host cells and evade lysosomal degradation, and a replicative form that multiplies within a phagosomal compartment that it has retooled to its advantage. The efficient changeover between transmissive and replicative states is fundamental to L. pneumophila's fitness as an intracellular pathogen. The transmission and replication programs of L. pneumophila are governed by a number of metabolic cues that signal whether conditions are favorable for replication or instead trigger escape from a spent host. Several lines of experimental evidence gathered over the past decade establish strong links between metabolism, cellular differentiation, and virulence of L. pneumophila. Herein, we focus on current knowledge of the metabolic components employed by intracellular L. pneumophila for cell differentiation, nutrient salvaging and utilization of host factors. Specifically, we highlight the metabolic cues that are coupled to bacterial differentiation, nutrient acquisition systems, and the strategies utilized by L. pneumophila to exploit host metabolites for intracellular replication.
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Affiliation(s)
- Maris V Fonseca
- Science and Mathematics Division, Monroe County Community College Monroe, MI, USA
| | - Michele S Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School Ann Arbor, MI, USA
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Listeria monocytogenes dairy isolates show a different proteome response to sequential exposure to gastric and intestinal fluids. Int J Food Microbiol 2013; 163:51-63. [PMID: 23558187 DOI: 10.1016/j.ijfoodmicro.2013.03.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 01/23/2013] [Accepted: 03/01/2013] [Indexed: 01/10/2023]
Abstract
The gastrointestinal system poses different stresses to the foodborne pathogen, Listeria monocytogenes, including the low pH of the stomach and the presence of bile and the high osmolality of the intestinal fluid. The present study evaluated how previous exposure of three L. monocytogenes dairy isolates (C882 and T8, serovar 4b isolates and A9 serovar 1/2a or 3b isolate) to a cheese-simulated medium (p H5.5 and 3.5% NaCl [w/v], adapted cultures) affected subsequent survival in a simulated gastrointestinal system. Listerial cultures exposed to the cheese-simulated medium at pH7.0, with no added NaCl, were considered non-adapted. To investigate the main events involved in listerial survival during the gastric and intestinal subsequent challenge, a proteomic approach was used. All L. monocytogenes strains were able to survive the deleterious effects of the gastrointestinal fluids and no significant differences were observed between adapted and non-adapted cells. However the L. monocytogenes strains showed a different protein pattern in response to the gastrointestinal stress. Data indicated that synthesis of stress related proteins is more pronounced in non-adapted cells. Although, a significant number of enzymes involved in glycolysis and energy production were also consistently over-produced by the three strains. These findings provided new insights into the means used by L. monocytogenes to overcome the gastrointestinal system and allow the pathogen to move to the next phase of the infectious process.
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Ignatova M, Guével B, Com E, Haddad N, Rossero A, Bogard P, Prévost H, Guillou S. Two-dimensional fluorescence difference gel electrophoresis analysis of Listeria monocytogenes submitted to a redox shock. J Proteomics 2013. [DOI: 10.1016/j.jprot.2012.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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29
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YuaB functions synergistically with the exopolysaccharide and TasA amyloid fibers to allow biofilm formation by Bacillus subtilis. J Bacteriol 2011; 193:4821-31. [PMID: 21742882 DOI: 10.1128/jb.00223-11] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During biofilm formation by Bacillus subtilis, two extracellular matrix components are synthesized, namely, the TasA amyloid fibers and an exopolysaccharide. In addition, a small protein called YuaB has been shown to allow the biofilm to form. The regulatory protein DegU is known to initiate biofilm formation. In this report we show that the main role of DegU during biofilm formation is to indirectly drive the activation of transcription from the yuaB promoter. The N terminus of YuaB constitutes a signal peptide for the Sec transport system. Here we show that the presence of the signal peptide is required for YuaB function. In addition we demonstrate that upon export of YuaB from the cytoplasm, it localizes to the cell wall. We continue with evidence that increased production of TasA and the exopolysaccharide is not sufficient to overcome the effects of a mutation in yuaB, demonstrating the unique involvement of YuaB in forming a biofilm. In line with this, YuaB is not involved in correct synthesis, export, or polymerization of either the TasA amyloid fibers or the exopolysaccharide. Taken together, these findings identify YuaB as a protein that plays a novel role during biofilm formation. We hypothesize that YuaB functions synergistically with the known components of the biofilm matrix to facilitate the assembly of the biofilm matrix.
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Quinn J, Malakasi P, Smith DA, Cheetham J, Buck V, Millar JBA, Morgan BA. Two-component mediated peroxide sensing and signal transduction in fission yeast. Antioxid Redox Signal 2011; 15:153-65. [PMID: 20919928 DOI: 10.1089/ars.2010.3345] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Two-component related proteins play a major role in regulating the oxidative stress response in the fission yeast, Schizosaccharomyces pombe. For example, the peroxide-sensing Mak2 and Mak3 histidine kinases regulate H(2)O(2)-induced activation of the Sty1 stress-activated protein kinase pathway, and the Skn7-related response regulator transcription factor, Prr1, is essential for activation of the core oxidative stress response genes. Here, we investigate the mechanism by which the S. pombe two-component system senses H(2)O(2), and the potential role of two-component signaling in the regulation of Prr1. Significantly, we demonstrate that PAS and GAF domains present in the Mak2 histidine kinase are essential for redox-sensing and activation of Sty1. In addition, we find that Prr1 is required for the transcriptional response to a wide range of H(2)O(2) concentrations and, furthermore, that two-component regulation of Prr1 is specifically required for the response of cells to high levels of H(2)O(2). Significantly, this provides the first demonstration that the conserved two-component phosphorylation site on Skn7-related proteins influences resistance to oxidative stress and oxidative stress-induced gene expression. Collectively, these data provide new insights into the two-component mediated sensing and signaling mechanisms underlying the response of S. pombe to oxidative stress.
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Affiliation(s)
- Janet Quinn
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
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31
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Abee T, Kovács AT, Kuipers OP, van der Veen S. Biofilm formation and dispersal in Gram-positive bacteria. Curr Opin Biotechnol 2010; 22:172-9. [PMID: 21109420 DOI: 10.1016/j.copbio.2010.10.016] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2010] [Revised: 10/26/2010] [Accepted: 10/26/2010] [Indexed: 11/25/2022]
Abstract
Biofilms are structured communities of bacteria, which are adhered to a surface and embedded in a self-produced matrix of extracellular polymeric substances. Since biofilms are very resistant to antimicrobial agents, they are at the basis of a range of problems, including quality and safety issues in food industry. Recently, major advances have been made in elucidating the different structural components of the biofilm matrix, the regulatory pathways involved in biofilm formation, and signaling molecules involved in biofilm formation and dispersal, which provide opportunities for prevention and control of these biofilms in the food industry.
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Affiliation(s)
- Tjakko Abee
- Top Institute Food and Nutrition, Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands.
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32
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Fritsch F, Mauder N, Williams T, Weiser J, Oberle M, Beier D. The cell envelope stress response mediated by the LiaFSRLm three-component system of Listeria monocytogenes is controlled via the phosphatase activity of the bifunctional histidine kinase LiaSLm. MICROBIOLOGY-SGM 2010; 157:373-386. [PMID: 21030435 DOI: 10.1099/mic.0.044776-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Most members of the phylum Firmicutes harbour a two-component system (TCS), LiaSR, which is involved in the response to cell envelope stress elicited most notably by inhibitors of the lipid II cycle. In all LiaSR systems studied in detail, LiaSR-mediated signal transduction has been shown to be negatively controlled by a membrane protein, LiaF, encoded upstream of liaSR. In this study we have analysed the LiaSR orthologue of Listeria monocytogenes (LiaSR(Lm)). Whole-genome transcriptional profiling indicated that activation of LiaSR(Lm) results in a remodelling of the cell envelope via the massive upregulation of membrane-associated and extracytoplasmic proteins in the presence of inducing stimuli. As shown for other LiaSR TCSs, LiaSR(Lm) is activated by cell wall-active antibiotics. We demonstrate that the level of phosphorylated LiaR(Lm), which is required for the induction of the LiaSR(Lm) regulon, is controlled by the interplay between the histidine kinase and phosphatase activities of the bifunctional sensor protein LiaS(Lm). Our data suggest that the phosphatase activity of LiaS(Lm) is stimulated by LiaF(Lm) in the absence of cell envelope stress.
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Affiliation(s)
- Frederike Fritsch
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Norman Mauder
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Tatjana Williams
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Julia Weiser
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Markus Oberle
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Dagmar Beier
- Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl für Mikrobiologie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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Steiner MS, Duerkop A. Luminescent ruthenium probe for the determination of acetyl phosphate in complex biological matrices. Analyst 2010; 136:148-54. [PMID: 20957243 DOI: 10.1039/c0an00439a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first probe for the fluorogenic determination of acetyl phosphate (AcP), (bpy)(2)Ru(1,10-phenanthroline-5,6-dione dioxime) (RuPDO), was prepared and its reaction with AcP was studied in detail. The emission of the weakly luminescent RuPDO is red shifted and strongly enhanced upon reaction with AcP in the presence of metal cations like Zn(2+) or Cu(2+). The reaction occurs within 60 min incubation time under highly biocompatible conditions (aqueous buffer of pH 7, 37 °C). A linear dynamic range from 10 to 200 µmol L(-1) is observed with an LOD of AcP of 3.4 µmol L(-1) (for RuPDO-Zn). Other bio-phosphates studied show only weak interference. Furthermore, the applicability of the probe in complex biological matrices was evaluated.
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Affiliation(s)
- Mark-Steven Steiner
- Institute of Analytical Chemistry, Chemo- and Biosensors, University of Regensburg, 93040 Regensburg, Germany
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Instability of ackA (acetate kinase) mutations and their effects on acetyl phosphate and ATP amounts in Streptococcus pneumoniae D39. J Bacteriol 2010; 192:6390-400. [PMID: 20952579 DOI: 10.1128/jb.00995-10] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Acetyl phosphate (AcP) is a small-molecule metabolite that can act as a phosphoryl group donor for response regulators of two-component systems (TCSs). The serious human respiratory pathogen Streptococcus pneumoniae (pneumococcus) synthesizes AcP by the conventional pathway involving phosphotransacetylase and acetate kinase, encoded by pta and ackA, respectively. In addition, pneumococcus synthesizes copious amounts of AcP and hydrogen peroxide (H(2)O(2)) by pyruvate oxidase, which is encoded by spxB. To assess possible roles of AcP in pneumococcal TCS regulation and metabolism, we constructed strains with combinations of spxB, pta, and ackA mutations and determined their effects on ATP, AcP, and H(2)O(2) production. Unexpectedly, ΔackA mutants were unstable and readily accumulated primary suppressor mutations in spxB or its positive regulator, spxR, thereby reducing H(2)O(2) and AcP levels, and secondary capsule mutations in cps2E or cps2C. ΔackA ΔspxB mutants contained half the cellular amount of ATP as a ΔspxB or spxB(+) strain. Acetate addition and anaerobic growth experiments suggested decreased ATP, rather than increased AcP, as a reason that ΔackA mutants accumulated spxB or spxR suppressors, although experimental manipulation of the AcP amount was limited. This finding and other considerations suggest that coping with endogenously produced H(2)O(2) may require energy. Starting with a ΔspxB mutant, we constructed Δpta, ΔackA, and Δpta ΔackA mutants. Epistasis and microarray experiment results were consistent with a role for the SpxB-Pta-AckA pathway in expression of the regulons controlled by the WalRK(Spn), CiaRH(Spn), and LiaSR(Spn) TCSs involved in sensing cell wall status. However, AcP likely does not play a physiological role in TCS sensing in S. pneumoniae.
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Kiley TB, Stanley-Wall NR. Post-translational control of Bacillus subtilis biofilm formation mediated by tyrosine phosphorylation. Mol Microbiol 2010; 78:947-63. [DOI: 10.1111/j.1365-2958.2010.07382.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Listeria monocytogenes PrsA2 is required for virulence factor secretion and bacterial viability within the host cell cytosol. Infect Immun 2010; 78:4944-57. [PMID: 20823208 DOI: 10.1128/iai.00532-10] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the course of establishing its replication niche within the cytosol of infected host cells, the facultative intracellular bacterial pathogen Listeria monocytogenes must efficiently regulate the secretion and activity of multiple virulence factors. L. monocytogenes encodes two predicted posttranslocation secretion chaperones, PrsA1 and PrsA2, and evidence suggests that PrsA2 has been specifically adapted for bacterial pathogenesis. PrsA-like chaperones have been identified in a number of Gram-positive bacteria, where they are reported to function at the bacterial membrane-cell wall interface to assist in the folding of proteins translocated across the membrane; in some cases, these proteins have been found to be essential for bacterial viability. In this study, the contributions of PrsA2 and PrsA1 to L. monocytogenes growth and protein secretion were investigated in vitro and in vivo. Neither PrsA2 nor PrsA1 was found to be essential for L. monocytogenes growth in broth culture; however, optimal bacterial viability was found to be dependent upon PrsA2 for L. monocytogenes located within the cytosol of host cells. Proteomic analyses of prsA2 mutant strains in the presence of a mutationally activated allele of the virulence regulator PrfA revealed a critical requirement for PrsA2 activity under conditions of PrfA activation, an event which normally takes place within the host cell cytosol. Despite a high degree of amino acid similarity, no detectable degree of functional overlap was observed between PrsA2 and PrsA1. Our results indicate a critical requirement for PrsA2 under conditions relevant to host cell infection.
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Cacace G, Mazzeo MF, Sorrentino A, Spada V, Malorni A, Siciliano RA. Proteomics for the elucidation of cold adaptation mechanisms in Listeria monocytogenes. J Proteomics 2010; 73:2021-30. [PMID: 20620249 DOI: 10.1016/j.jprot.2010.06.011] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 05/06/2010] [Accepted: 06/23/2010] [Indexed: 11/25/2022]
Abstract
Listeria monocytogenes, one of the major food-related pathogens, is the aetiological agent of listeriosis, a potentially life-threatening illness. It is able to survive in hostile environments and stress conditions such as those encountered in food-processing technologies (high salt concentration, wide range of pH and temperature, low water availability) and it also thrives at temperatures ranging from -0.4 to 45 °C. In this study, expression proteomics was applied to gain insight into key cellular events that allow L. monocytogenes to survive and multiply even at refrigeration temperatures. Interestingly, we observed that the adaptation processes mainly affect biochemical pathways related to protein synthesis and folding, nutrient uptake and oxidative stress. Furthermore, proteins implicated in metabolic pathways for energy production, such as glycolysis and Pta-AckA pathway, were present to a higher level in the cells grown at 4 °C. This suggests that, on the whole, cells exhibit an enhanced demand for energy to sustain cold growth. Proteomics may represent a key tool in deciphering specific mechanisms underlying cold adaptation response and, more widely, cell machinery.
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Affiliation(s)
- Giuseppina Cacace
- Proteomic and Biomolecular Mass Spectrometry Center, Institute of Food Science, CNR, Avellino, Italy
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Moreno-Paz M, Gómez MJ, Arcas A, Parro V. Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial community. BMC Genomics 2010; 11:404. [PMID: 20576116 PMCID: PMC2996932 DOI: 10.1186/1471-2164-11-404] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 06/24/2010] [Indexed: 12/17/2022] Open
Abstract
Background Extreme acidic environments are characterized by their high metal content and lack of nutrients (oligotrophy). Macroscopic biofilms and filaments usually grow on the water-air interface or under the stream attached to solid substrates (streamers). In the Río Tinto (Spain), brown filaments develop under the water stream where the Gram-negative iron-oxidizing bacteria Leptospirillum spp. (L. ferrooxidans and L. ferriphilum) and Acidithiobacillus ferrooxidans are abundant. These microorganisms play a critical role in bioleaching processes for industrial (biominery) and environmental applications (acid mine drainage, bioremediation). The aim of this study was to investigate the physiological differences between the free living (planktonic) and the sessile (biofilm associated) lifestyles of Leptospirillum spp. as part of its natural extremely acidophilic community. Results Total RNA extracted from environmental samples was used to determine the composition of the metabolically active members of the microbial community and then to compare the biofilm and planktonic environmental transcriptomes by hybridizing to a genomic microarray of L. ferrooxidans. Genes up-regulated in the filamentous biofilm are involved in cellular functions related to biofilm formation and maintenance, such as: motility and quorum sensing (mqsR, cheAY, fliA, motAB), synthesis of cell wall structures (lnt, murA, murB), specific proteases (clpX/clpP), stress response chaperons (clpB, clpC, grpE-dnaKJ, groESL), etc. Additionally, genes involved in mixed acid fermentation (poxB, ackA) were up-regulated in the biofilm. This result, together with the presence of small organic acids like acetate and formate (1.36 mM and 0.06 mM respectively) in the acidic (pH 1.8) water stream, suggests that either L. ferrooxidans or other member of the microbial community are producing acetate in the acidophilic biofilm under microaerophilic conditions. Conclusions Our results indicate that the acidophilic filaments are dynamic structures in which different mechanisms for biofilm formation/dispersion are operating. Specific transcriptomic fingerprints can be inferred for both planktonic and sessile cells, having the former a more active TCA cycle, while the mixed acid fermentation process dominate in the latter. The excretion of acetate may play a relevant ecological role as a source of electron donor for heterotrophic Fe3+ reducers like some Alphaproteobacteria, Acidobacterium spp. and Sulfobacillus spp., also present in the biofilm. Additionally, acetate may have a negative effect on bioleaching by inhibiting the growth of chemolithotrophic bacteria.
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Affiliation(s)
- Mercedes Moreno-Paz
- Department of Molecular Evolution, Centro de Astrobiología (INTA-CSIC), Madrid, Spain
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Zakikhany K, Harrington CR, Nimtz M, Hinton JCD, Römling U. Unphosphorylated CsgD controls biofilm formation in Salmonella enterica serovar Typhimurium. Mol Microbiol 2010; 77:771-86. [PMID: 20545866 DOI: 10.1111/j.1365-2958.2010.07247.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The transcriptional regulator CsgD of Salmonella enterica serovar Typhimurium (S. Typhimurium) is a major regulator of biofilm formation required for the expression of csgBA, which encodes curli fimbriae, and adrA, coding for a diguanylate cyclase. CsgD is a response regulator with an N-terminal receiver domain with a conserved aspartate (D59) as a putative target site for phosphorylation and a C-terminal LuxR-like helix-turn-helix DNA binding motif, but the mechanisms of target gene activation remained unclear. To study the DNA-binding properties of CsgD we used electrophoretic mobility shift assays and DNase I footprint analysis to show that unphosphorylated CsgD-His(6) binds specifically to the csgBA and adrA promoter regions. In vitro transcription analysis revealed that CsgD-His(6) is crucial for the expression of csgBA and adrA. CsgD-His(6) is phosphorylated by acetyl phosphate in vitro, which decreases its DNA-binding properties. The functional impact of D59 in vivo was demonstrated as S. Typhimurium strains expressing modified CsgD protein (D59E and D59N) were dramatically reduced in biofilm formation due to decreased protein stability and DNA-binding properties in the case of D59E. In summary, our findings suggest that the response regulator CsgD functions in its unphosphorylated form under the conditions of biofilm formation investigated in this study.
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Affiliation(s)
- Katherina Zakikhany
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, FE 280, 17177 Stockholm, Sweden
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Wolfe AJ. Physiologically relevant small phosphodonors link metabolism to signal transduction. Curr Opin Microbiol 2010; 13:204-9. [PMID: 20117041 PMCID: PMC2847653 DOI: 10.1016/j.mib.2010.01.002] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 01/04/2010] [Accepted: 01/07/2010] [Indexed: 11/17/2022]
Abstract
Recent reports support the long-standing hypothesis that acetyl phosphate, a physiologically relevant small molecule, can serve as a phosphoryl donor to a subset of two-component response regulators that regulate diverse cellular processes. Since acetyl phosphate is a central metabolite, this ability would link nutritional status to global signaling. This review will first introduce acetyl phosphate and its pathway. It will then summarize the most compelling evidence supporting the hypothesis and list predicted properties of an acetyl phosphate-sensitive pathway. Next, it will describe emerging evidence that acetyl phosphate and/or its pathway can influence diverse cellular processes across a broad spectrum of bacteria. Finally, the review will explore the possibility that other metabolites can function in a capacity similar to acetyl phosphate.
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Affiliation(s)
- Alan J Wolfe
- Department of Microbiology and Immunology, Loyola University Chicago, Stritch School of Medicine, 2160 S. First Ave., Bldg. 105, Maywood, IL 60153, USA
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Novel antibacterial compounds specifically targeting the essential WalR response regulator. J Antibiot (Tokyo) 2010; 63:127-34. [PMID: 20111065 DOI: 10.1038/ja.2010.4] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The WalK/WalR (YycG/YycF) two-component system, which is essential for cell viability, is highly conserved and specific to low-GC percentage of Gram-positive bacteria, making it an attractive target for novel antimicrobial compounds. Recent work has shown that WalK/WalR exerts an effect as a master regulatory system in controlling and coordinating cell wall metabolism with cell division in Bacillus subtilis and Staphylococcus aureus. In this paper, we develop a high-throughput screening system for WalR inhibitors and identify two novel inhibitors targeting the WalR response regulator (RR): walrycin A (4-methoxy-1-naphthol) and walrycin B (1,6-dimethyl-3-[4-(trifluoromethyl)phenyl]pyrimido[5,4-e][1,2,4]triazine-5,7-dione). Addition of these compounds simultaneously affects the expression of WalR regulon genes, leading to phenotypes consistent with those of cells starved for the WalK/WalR system and having a bactericidal effect. B. subtilis cells form extremely long aseptate filaments and S. aureus cells form large aggregates under these conditions. These results show that walrycins A and B are the first antibacterial agents targeting WalR in B. subtilis and S. aureus.
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Differential target gene activation by the Staphylococcus aureus two-component system saeRS. J Bacteriol 2009; 192:613-23. [PMID: 19933357 DOI: 10.1128/jb.01242-09] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The saePQRS system of Staphylococcus aureus controls the expression of major virulence factors and encodes a histidine kinase (SaeS), a response regulator (SaeR), a membrane protein (SaeQ), and a lipoprotein (SaeP). The widely used strain Newman is characterized by a single amino acid change in the sensory domain of SaeS (Pro18 in strain Newman [SaeS(P)], compared with Leu18 in other strains [SaeS(L)]). SaeS(P) determines activation of the class I sae target genes (coa, fnbA, eap, sib, efb, fib, sae), which are highly expressed in strain Newman. In contrast, class II target genes (hla, hlb, cap) are not sensitive to the SaeS polymorphism. The SaeS(L) allele (saeS(L)) is dominant over the SaeS(P) allele, as shown by single-copy integration of saePQRS(L) in strain Newman, which results in severe repression of class I target genes. The differential effect on target gene expression is explained by different requirements for SaeR phosphorylation. From an analysis of saeS deletion strains and strains with mutated SaeR phosphorylation sites, we concluded that a high level of SaeR phosphorylation is required for activation of class I target genes. However, a low level of SaeR phosphorylation, which can occur independent of SaeS, is sufficient to activate class II target genes. Using inducible saeRS constructs, we showed that the expression of both types of target genes is independent of the saeRS dosage and that the typical growth phase-dependent gene expression pattern is not driven by SaeRS.
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Dumas E, Meunier B, Berdagué JL, Chambon C, Desvaux M, Hébraud M. The origin of Listeria monocytogenes 4b isolates is signified by subproteomic profiling. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:1530-6. [DOI: 10.1016/j.bbapap.2009.06.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2009] [Revised: 06/17/2009] [Accepted: 06/29/2009] [Indexed: 11/27/2022]
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Kamp HD, Higgins DE. Transcriptional and post-transcriptional regulation of the GmaR antirepressor governs temperature-dependent control of flagellar motility in Listeria monocytogenes. Mol Microbiol 2009; 74:421-35. [PMID: 19796338 DOI: 10.1111/j.1365-2958.2009.06874.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Flagellar motility in Listeria monocytogenes (Lm) is restricted to temperatures below 37 degrees C due to the opposing activities of the MogR transcriptional repressor and the GmaR antirepressor. Previous studies have suggested that both the DegU response regulator and MogR regulate expression of GmaR. In this report, we further define the role of DegU for GmaR production and flagellar motility. We demonstrate that deletion of the receiver domain of DegU has no effect on flagellar motility in Lm. Using transcriptional reporter fusions, we determined that gmaR is cotranscribed within an operon initiating with fliN. Furthermore, the fliN-gmaR promoter (p(fliN-gmaR)) is transcriptionally activated by DegU and is also MogR-repressed. DNA affinity purification, gel mobility shift and footprinting analyses revealed that both DegU and MogR directly bind fliN-gmaR promoter region DNA and that the binding sites do not overlap. Quantitative analysis of gmaR transcripts in Delta mogR bacteria indicated that transcriptional activation of p(fliN-gmaR) by DegU is not inherently temperature-dependent. However, GmaR protein was not detectable at 37 degrees C in Delta mogR bacteria, indicating that a temperature-dependent, post-transcriptional mechanism limits GmaR production to temperatures below 37 degrees C. Our findings reveal that flagellar motility in Lm is governed by both temperature-dependent transcriptional and post-transcriptional regulation of the GmaR antirepressor.
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Affiliation(s)
- Heather D Kamp
- Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115-6092, USA
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ResDE-dependent regulation of enterotoxin gene expression in Bacillus cereus: evidence for multiple modes of binding for ResD and interaction with Fnr. J Bacteriol 2009; 191:4419-26. [PMID: 19395489 DOI: 10.1128/jb.00321-09] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the food-borne pathogen Bacillus cereus F4430/73, the production of major virulence factors hemolysin BL (Hbl) and nonhemolytic enterotoxin (Nhe) is regulated through complex mechanisms. The two-component regulatory system ResDE is involved in the activation of hbl and nhe transcription. Here, the response regulator ResD and the sensor kinase ResE were overexpressed and purified, and autophosphorylation of ResE and transphosphorylation of ResD by ResE were demonstrated in vitro. ResD is mainly monomeric in solution, regardless of its phosphorylation state. ResD was shown to interact directly with promoter regions (p) of the enterotoxin regulator genes resDE, fnr, and plcR and the enterotoxin structural genes nhe and hbl, but with different affinities. Binding of ResD to pplcR, pnhe, and phbl was not dependent on the ResD phosphorylation status. In contrast, ResD phosphorylation significantly increased interactions between ResD and presDE and pfnr. Taken together, these results showed that phosphorylation of ResD results in a different target expression pattern. Furthermore, ResD and the redox activator Fnr were found to physically interact and simultaneously bind their target DNAs. We propose that unphosphorylated ResD acts as an antiactivator of Fnr, while phosphorylated ResD acts as a coactivator of Fnr. Finally, our findings represent the first molecular evidence of the role of ResDE as a sentinel system capable of sensing redox changes and coordinating a response that modulates B. cereus virulence.
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Murray EJ, Kiley TB, Stanley-Wall NR. A pivotal role for the response regulator DegU in controlling multicellular behaviour. MICROBIOLOGY-SGM 2009; 155:1-8. [PMID: 19118340 DOI: 10.1099/mic.0.023903-0] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacteria control multicellular behavioural responses, including biofilm formation and swarming motility, by integrating environmental cues through a complex regulatory network. Heterogeneous gene expression within an otherwise isogenic cell population that allows for differentiation of cell fate is an intriguing phenomenon that adds to the complexity of multicellular behaviour. This review focuses on recent data about how DegU, a pleiotropic response regulator, co-ordinates multicellular behaviour in Bacillus subtilis. We review studies that challenge the conventional understanding of the molecular mechanisms underpinning the DegU regulatory system and others that describe novel targets of DegU during activation of biofilm formation by B. subtilis. We also discuss a novel role for DegU in regulating multicellular processes in the food-borne pathogen Listeria monocytogenes.
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Affiliation(s)
- Ewan J Murray
- Division of Molecular and Environmental Microbiology, College of Life Sciences, MSI/WTB/JBC Complex, University of Dundee, Dundee DD1 5EH, UK
| | - Taryn B Kiley
- Division of Molecular and Environmental Microbiology, College of Life Sciences, MSI/WTB/JBC Complex, University of Dundee, Dundee DD1 5EH, UK
| | - Nicola R Stanley-Wall
- Division of Molecular and Environmental Microbiology, College of Life Sciences, MSI/WTB/JBC Complex, University of Dundee, Dundee DD1 5EH, UK
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