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Chang J, Zhou Y, Li X, Zhang M, Zhang Y, Ni B, Lu R. Identification of an LysR family transcriptional regulator that activates motility and flagellar gene expression in Vibrio parahaemolyticus. Lett Appl Microbiol 2024; 77:ovae059. [PMID: 38906839 DOI: 10.1093/lambio/ovae059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 05/20/2024] [Accepted: 06/19/2024] [Indexed: 06/23/2024]
Abstract
Vibrio parahaemolyticus utilizes a polar flagellum for swimming in liquids and employs multiple lateral flagella to swarm on surfaces and in viscous environments. The VPA0961 protein is an LysR family transcriptional regulator that can regulate the swimming and swarming motility of V. parahaemolyticus, but the detailed regulatory mechanisms are not yet fully understood. Herein, we designated the protein as AcsS, which stands for activator of swimming and swarming motility. Our data provided evidence that deleting the acsS gene significantly reduced both swimming and swarming motility of V. parahaemolyticus. Furthermore, AcsS was found to activate the expression of both polar (flgA, flgM, flgB, and flgK) and lateral (motY, fliM, lafA, and fliD) flagellar genes. Overexpression of AcsS in Escherichia coli induced the expression of flgA, motY, and lafA, but did not affect the expression of flgB, flgK, flgM, fliM, and fliD. Interestingly, His-tagged AcsS did not bind to the upstream DNA regions of all the tested genes, suggesting indirect regulation. In conclusion, AcsS positively regulated the swimming and swarming motility of V. parahaemolyticus by activating the transcription of polar and lateral flagellar genes. This work enriched our understanding of the gene expression regulation within the dual flagellar systems of V. parahaemolyticus.
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Affiliation(s)
- Jingyang Chang
- Department of laboratory Medicine, School of Medicine, Jiangsu University, Zhenjiang, 212013 Jiangsu, China
- Department of Clinical Laboratory, Nantong Third People's Hospital, Affiliated Nantong Hospital 3 of Nantong University, Nantong, 226006 Jiangsu, China
| | - Yining Zhou
- Department of laboratory Medicine, School of Medicine, Jiangsu University, Zhenjiang, 212013 Jiangsu, China
- Department of Clinical Laboratory, Nantong Third People's Hospital, Affiliated Nantong Hospital 3 of Nantong University, Nantong, 226006 Jiangsu, China
| | - Xue Li
- Department of Clinical Laboratory, Nantong Third People's Hospital, Affiliated Nantong Hospital 3 of Nantong University, Nantong, 226006 Jiangsu, China
| | - Miaomiao Zhang
- Department of Clinical Laboratory, Nantong Third People's Hospital, Affiliated Nantong Hospital 3 of Nantong University, Nantong, 226006 Jiangsu, China
| | - Yiquan Zhang
- Department of Clinical Laboratory, Nantong Third People's Hospital, Affiliated Nantong Hospital 3 of Nantong University, Nantong, 226006 Jiangsu, China
| | - Bin Ni
- Department of laboratory Medicine, School of Medicine, Jiangsu University, Zhenjiang, 212013 Jiangsu, China
| | - Renfei Lu
- Department of Clinical Laboratory, Nantong Third People's Hospital, Affiliated Nantong Hospital 3 of Nantong University, Nantong, 226006 Jiangsu, China
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Leleiwi I, Kokkinias K, Kim Y, Baniasad M, Shaffer M, Sabag-Daigle A, Daly RA, Flynn RM, Wysocki VH, Ahmer BMM, Borton MA, Wrighton KC. Gut microbiome carbon and sulfur metabolisms support Salmonella during pathogen infection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.16.575907. [PMID: 38293109 PMCID: PMC10827160 DOI: 10.1101/2024.01.16.575907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Salmonella enterica serovar Typhimurium is a pervasive enteric pathogen and an ongoing global threat to public health. Ecological studies in the Salmonella impacted gut remain underrepresented in the literature, discounting the microbiome mediated interactions that may inform Salmonella physiology during colonization and infection. To understand the microbial ecology of Salmonella remodeling of the gut microbiome, here we performed multi-omics approaches on fecal microbial communities from untreated and Salmonella -infected mice. Reconstructed genomes recruited metatranscriptomic and metabolomic data providing a strain-resolved view of the expressed metabolisms of the microbiome during Salmonella infection. This data informed possible Salmonella interactions with members of the gut microbiome that were previously uncharacterized. Salmonella- induced inflammation significantly reduced the diversity of transcriptionally active members in the gut microbiome, yet increased gene expression was detected for 7 members, with Luxibacter and Ligilactobacillus being the most active. Metatranscriptomic insights from Salmonella and other persistent taxa in the inflamed microbiome further expounded the necessity for oxidative tolerance mechanisms to endure the host inflammatory responses to infection. In the inflamed gut lactate was a key metabolite, with microbiota production and consumption reported amongst transcriptionally active members. We also showed that organic sulfur sources could be converted by gut microbiota to yield inorganic sulfur pools that become oxidized in the inflamed gut, resulting in thiosulfate and tetrathionate that supports Salmonella respiration. Advancement of pathobiome understanding beyond inferences from prior amplicon-based approaches can hold promise for infection mitigation, with the active community outlined here offering intriguing organismal and metabolic therapeutic targets.
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Liu F, Qiao K, Meng W, Liu J, Gao Y, Zhu J. Construction of a CRISPR Interference System for Gene Knockdown in Stenotrophomonas maltophilia AGS-1 from Aerobic Granular Sludge. ACS Synth Biol 2023; 12:3497-3504. [PMID: 37906167 DOI: 10.1021/acssynbio.3c00480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
To identify the function of attachment genes involved in biofilm formation in Stenotrophomonas maltophilia AGS-1 isolated from aerobic granular sludge, an effective gene molecular tool is needed. We developed a two-plasmid CRISPRi system in Stenotrophomonas maltophilia AGS-1. One plasmid expressed dCas9 protein with the l-arabinose inducible promoter, and the other plasmid contained the sgRNA cassette complementary to the target gene. Under control of the araC-inducible promoter, this system exhibited little leaky basal expression and highly induced expression that silenced endogenous and exogenous genes with reversible knockdown. This system achieved up to 211-fold suppression for mCherry expression on the nontemplate strand compared to the template strand (91-fold). The utility of the developed CRISPRi platform was also characterized by suppressing the xanA and rpfF genes. The expression of these two genes was rapidly depleted and the adhesion ability decreased, which demonstrated that the modulation of either gene was an important factor for biofilm formation of the AGS-1 strain. The system also tested the ability to simultaneously silence transcriptional suppression of multiple targeted genes, an entire operon, or part of it. Lastly, the use of CRISPRi allowed us to dissect the gene intricacies involved in flagellar biosynthesis. Collectively, these results demonstrated that the CRISPRi system was a simple, feasible, and controllable manipulation system of gene expression in the AGS-1 strain.
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Affiliation(s)
- Fan Liu
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
| | - Kai Qiao
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Wei Meng
- School of Environment, Beijing Normal University, Beijing 100875, China
- State Key Laboratory of Water Simulation, Beijing 100875, China
| | - Jia Liu
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Yiyun Gao
- School of Environment, Beijing Normal University, Beijing 100875, China
| | - Jianrong Zhu
- School of Environment, Beijing Normal University, Beijing 100875, China
- R & D Centre of Aerobic Granule Technology, Beijing 100875, China
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4
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Alberti L, König P, Zeidler S, Poehlein A, Daniel R, Averhoff B, Müller V. Identification and characterization of a novel pathway for aldopentose degradation in Acinetobacter baumannii. Environ Microbiol 2023; 25:2416-2430. [PMID: 37522309 DOI: 10.1111/1462-2920.16471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 07/14/2023] [Indexed: 08/01/2023]
Abstract
The nosocomial pathogen Acinetobacter baumannii is well known for its extraordinary metabolic diversity. Recently, we demonstrated growth on L-arabinose, but the pathway remained elusive. Transcriptome analyses revealed two upregulated gene clusters that code for isoenzymes catalysing oxidation of a pentonate to α-ketoglutarate. Molecular, genetic, and biochemical experiments revealed one branch to be specific for L-arabonate oxidation, and the other for D-xylonate and D-ribonate. Both clusters also encode an uptake system and a regulator that acts as activator (L-arabonate) or repressor (D-xylonate and D-ribonate). Genes encoding the initial oxidation of pentose to pentonate were not part of the clusters, but our data are consistent with the hypothesis of a promiscous, pyrroloquinoline quinone (PQQ)-dependent, periplasmic pentose dehydrogenase, followed by the uptake of the pentonates and their degradation by specific pathways. However, there is a cross-talk between the two different pathways since the isoenzymes can replace each other. Growth on pentoses was found only in pathogenic Acinetobacter species but not in non-pathogenic such as Acinetobacter baylyi. However, mutants impaired in growth on pentoses were not affected in traits important for infection, but growth on L-arabinose was beneficial for long-term survival and desiccation resistance in A. baumannii ATCC 19606.
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Affiliation(s)
- Lydia Alberti
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Patricia König
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Sabine Zeidler
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology and Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, University of Göttingen, Göttingen, Germany
| | - Beate Averhoff
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
| | - Volker Müller
- Department of Molecular Microbiology & Bioenergetics, Institute of Molecular Biosciences, Goethe-University Frankfurt am Main, Frankfurt, Germany
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Naseri G, Raasch H, Charpentier E, Erhardt M. A versatile regulatory toolkit of arabinose-inducible artificial transcription factors for Enterobacteriaceae. Commun Biol 2023; 6:1005. [PMID: 37789111 PMCID: PMC10547716 DOI: 10.1038/s42003-023-05363-3] [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: 05/31/2023] [Accepted: 09/15/2023] [Indexed: 10/05/2023] Open
Abstract
The Gram-negative bacteria Salmonella enterica and Escherichia coli are important model organisms, powerful prokaryotic expression platforms for biotechnological applications, and pathogenic strains constitute major public health threats. To facilitate new approaches for research and biotechnological applications, we here develop a set of arabinose-inducible artificial transcription factors (ATFs) using CRISPR/dCas9 and Arabidopsis-derived DNA-binding proteins to control gene expression in E. coli and Salmonella over a wide inducer concentration range. The transcriptional output of the different ATFs, in particular when expressed in Salmonella rewired for arabinose catabolism, varies over a wide spectrum (up to 35-fold gene activation). As a proof-of-concept, we use the developed ATFs to engineer a Salmonella two-input biosensor strain, SALSOR 0.2 (SALmonella biosenSOR 0.2), which detects and quantifies alkaloid drugs through a measurable fluorescent output. Moreover, we use plant-derived ATFs to regulate β-carotene biosynthesis in E. coli, resulting in ~2.1-fold higher β-carotene production compared to expression of the biosynthesis pathway using a strong constitutive promoter.
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Affiliation(s)
- Gita Naseri
- Max Planck Unit for the Science of Pathogens, Charitéplatz 1, 10117, Berlin, Germany.
- Institut für Biologie, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115, Berlin, Germany.
| | - Hannah Raasch
- Institut für Biologie, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115, Berlin, Germany
| | - Emmanuelle Charpentier
- Max Planck Unit for the Science of Pathogens, Charitéplatz 1, 10117, Berlin, Germany
- Institut für Biologie, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115, Berlin, Germany
| | - Marc Erhardt
- Max Planck Unit for the Science of Pathogens, Charitéplatz 1, 10117, Berlin, Germany.
- Institut für Biologie, Humboldt-Universität zu Berlin, Philippstrasse 13, 10115, Berlin, Germany.
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6
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Zhang M, Luo X, Li X, Zhang T, Wu F, Li M, Lu R, Zhang Y. L-arabinose affects the growth, biofilm formation, motility, c-di-GMP metabolism, and global gene expression of Vibrio parahaemolyticus. J Bacteriol 2023; 205:e0010023. [PMID: 37655915 PMCID: PMC10521368 DOI: 10.1128/jb.00100-23] [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: 03/15/2023] [Accepted: 07/24/2023] [Indexed: 09/02/2023] Open
Abstract
The L-arabinose inducible pBAD vectors are commonly used to turn on and off the expression of specific genes in bacteria. The utilization of certain carbohydrates can influence bacterial growth, virulence factor production, and biofilm formation. Vibrio parahaemolyticus, the causative agent of seafood-associated gastroenteritis, can grow in media with L-arabinose as the sole carbon source. However, the effects of L-arabinose on V. parahaemolyticus physiology have not been investigated. In this study, we show that the growth rate, biofilm formation capacity, capsular polysaccharide production, motility, and c-di-GMP production of V. parahaemolyticus are negatively affected by L-arabinose. RNA-seq data revealed significant changes in the expression levels of 752 genes, accounting for approximately 15.6% of V. parahaemolyticus genes in the presence of L-arabinose. The affected genes included those associated with L-arabinose utilization, major virulence genes, known key biofilm-related genes, and numerous regulatory genes. In the majority of type III secretion system, two genes were upregulated in the presence of L-arabinose, whereas in those of type VI secretion system, two genes were downregulated. Ten putative c-di-GMP metabolism-associated genes were also significantly differentially expressed, which may account for the reduced c-di-GMP levels in the presence of L-arabinose. Most importantly, almost 40 putative regulators were significantly differentially expressed due to the induction by L-arabinose, indicating that the utilization of L-arabinose is strictly regulated by regulatory networks in V. parahaemolyticus. The findings increase the understanding of how L-arabinose affects the physiology of V. parahaemolyticus. Researchers should use caution when considering the use of L-arabinose inducible pBAD vectors in V. parahaemolyticus. IMPORTANCE The data in this study show that L-arabinose negatively affects the growth rate, biofilm formation, capsular polysaccharide production, motility, and c-di-GMP production of V. parahaemolyticus. The data also clarify the gene expression profiles of the bacterium in the presence of L-arabinose. Significantly differentially expressed genes in response to L-arabinose were involved in multiple cellular pathways, including L-arabinose utilization, virulence factor production, biofilm formation, motility, adaptation, and regulation. The collective findings indicate the significant impact of L-arabinose on the physiology of V. parahaemolyticus. There may be similar effects on other species of bacteria. Necessary controls should be established when pBAD vectors must be used for ectopic gene expression.
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Affiliation(s)
- Miaomiao Zhang
- Department of Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
| | - Xi Luo
- Department of Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
| | - Xue Li
- Department of Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
| | - Tingting Zhang
- Department of Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
- School of Medicine, Nantong University, Nantong, Jiangsu, China
| | - Fei Wu
- Department of Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
| | - Min Li
- Department of Gastroenterology and Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
| | - Renfei Lu
- Department of Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
| | - Yiquan Zhang
- Department of Clinical Laboratory, Affiliated Nantong Hospital 3 of Nantong University, Nantong Third People's Hospital, Nantong, Jiangsu, China
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7
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Gül E, Abi Younes A, Huuskonen J, Diawara C, Nguyen BD, Maurer L, Bakkeren E, Hardt WD. Differences in carbon metabolic capacity fuel co-existence and plasmid transfer between Salmonella strains in the mouse gut. Cell Host Microbe 2023; 31:1140-1153.e3. [PMID: 37348498 DOI: 10.1016/j.chom.2023.05.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 04/12/2023] [Accepted: 05/26/2023] [Indexed: 06/24/2023]
Abstract
Antibiotic resistance plasmids can be disseminated between different Enterobacteriaceae in the gut. Here, we investigate how closely related Enterobacteriaceae populations with similar nutrient needs can co-bloom in the same gut and thereby facilitate plasmid transfer. Using different strains of Salmonella Typhimurium (S.Tm SL1344 and ATCC14028) and mouse models of Salmonellosis, we show that the bloom of one strain (i.e., recipient) from very low numbers in a gut pre-occupied by the other strain (i.e., donor) depends on strain-specific utilization of a distinct carbon source, galactitol or arabinose. Galactitol-dependent growth of the recipient S.Tm strain promotes plasmid transfer between non-isogenic strains and between E. coli and S.Tm. In mice stably colonized by a defined microbiota (OligoMM12), galactitol supplementation similarly facilitates co-existence of two S.Tm strains and promotes plasmid transfer. Our work reveals a metabolic strategy used by Enterobacteriaceae to expand in a pre-occupied gut and provides promising therapeutic targets for resistance plasmids spread.
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Affiliation(s)
- Ersin Gül
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland.
| | - Andrew Abi Younes
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Jemina Huuskonen
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Cheickna Diawara
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Bidong D Nguyen
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Luca Maurer
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Erik Bakkeren
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, 8093 Zurich, Switzerland.
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8
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Ruddle SJ, Massis LM, Cutter AC, Monack DM. Salmonella-liberated dietary L-arabinose promotes expansion in superspreaders. Cell Host Microbe 2023; 31:405-417.e5. [PMID: 36812913 PMCID: PMC10016319 DOI: 10.1016/j.chom.2023.01.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 12/23/2022] [Accepted: 01/27/2023] [Indexed: 02/24/2023]
Abstract
The molecular understanding of host-pathogen interactions in the gastrointestinal (GI) tract of superspreader hosts is incomplete. In a mouse model of chronic, asymptomatic Salmonella enterica serovar Typhimurium (S. Tm) infection, we performed untargeted metabolomics on the feces of mice and found that superspreader hosts possess distinct metabolic signatures compared with non-superspreaders, including differential levels of L-arabinose. RNA-seq on S. Tm from superspreader fecal samples showed increased expression of the L-arabinose catabolism pathway in vivo. By combining bacterial genetics and diet manipulation, we demonstrate that diet-derived L-arabinose provides S. Tm a competitive advantage in the GI tract, and expansion of S. Tm in the GI tract requires an alpha-N-arabinofuranosidase that liberates L-arabinose from dietary polysaccharides. Ultimately, our work shows that pathogen-liberated L-arabinose from the diet provides a competitive advantage to S. Tm in vivo. These findings propose L-arabinose as a critical driver of S. Tm expansion in the GI tracts of superspreader hosts.
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Affiliation(s)
- Sarah J Ruddle
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Liliana M Massis
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alyssa C Cutter
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Denise M Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
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9
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Buck LD, Paladino MM, Nagashima K, Brezel ER, Holtzman JS, Urso SJ, Ryno LM. Temperature-Dependent Influence of FliA Overexpression on PHL628 E. coli Biofilm Growth and Composition. Front Cell Infect Microbiol 2022; 11:775270. [PMID: 34976858 PMCID: PMC8718923 DOI: 10.3389/fcimb.2021.775270] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/29/2021] [Indexed: 11/13/2022] Open
Abstract
Biofilm growth and survival pose a problem in both medical and industrial fields. Bacteria in biofilms are more tolerant to antibiotic treatment due to the inability of antibiotics to permeate to the bottom layers of cells in a biofilm and the creation of altered microenvironments of bacteria deep within the biofilm. Despite the abundance of information we have about E. coli biofilm growth and maturation, we are still learning how manipulating different signaling pathways influences the formation and fitness of biofilm. Understanding the impact of signaling pathways on biofilm formation may narrow the search for novel small molecule inhibitors or activators that affect biofilm production and stability. Here, we study the influence of the minor sigma transcription factor FliA (RpoF, sigma-28), which controls late-stage flagellar assembly and chemotaxis, on biofilm production and composition at various temperatures in the E. coli strain PHL628, which abundantly produces the extracellular structural protein curli. We examined FliA's influence on external cellular structures like curli and flagella and the biomolecular composition of the biofilm's extracellular polymeric substance (EPS) using biochemical assays, immunoblotting, and confocal laser scanning microscopy (CLSM). At 37°C, FliA overexpression results in the dramatic growth of biofilm in polystyrene plates and more modest yet significant biofilm growth on silica slides. We observed no significant differences in curli concentration and carbohydrate concentration in the EPS with FliA overexpression. Still, we did see significant changes in the abundance of EPS protein using CLSM at higher growth temperatures. We also noticed increased flagellin concentration, a major structural protein in flagella, occurred with FliA overexpression, specifically in planktonic cultures. These experiments have aided in narrowing our focus to FliA's role in changing the protein composition of the EPS, which we will examine in future endeavors.
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Affiliation(s)
- Luke D Buck
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Maddison M Paladino
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Kyogo Nagashima
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Emma R Brezel
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Joshua S Holtzman
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Sarel J Urso
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
| | - Lisa M Ryno
- Department of Chemistry and Biochemistry, Oberlin College, Oberlin, OH, United States
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