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Brown-Elliott BA, Wallace RJ, Wengenack NL, Workman SD, Cameron ADS, Bush G, Hughes MD, Melton S, Gonzalez-Ramirez B, Rodriguez E, Somayaji K, Klapperich C, Viers M, Bolaji AJ, Rempel E, Alexander DC. Erratum for Brown-Elliott et al., "Emergence of Inducible Macrolide Resistance in Mycobacterium chelonae Due to Broad-Host-Range Plasmid and Chromosomal Variants of the Novel 23S rRNA Methylase Gene, erm(55)". J Clin Microbiol 2024; 62:e0041524. [PMID: 38572983 PMCID: PMC11077984 DOI: 10.1128/jcm.00415-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2024] Open
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2
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Haidl TH, Lee MK, Workman SD, Russell JN, Fraser E, Morshed MG, Cameron ADS. Draft whole-genome sequences of three Borrelia burgdorferi isolates from Western Canada. Microbiol Resour Announc 2024; 13:e0087923. [PMID: 38179914 PMCID: PMC10868169 DOI: 10.1128/mra.00879-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 12/10/2023] [Indexed: 01/06/2024] Open
Abstract
Whole-genome sequences are presented for three Borrelia burgdorferi, a causative agent of Lyme disease in North America, isolated from Ixodes pacificus ticks collected in British Columbia, Canada. Shotgun DNA libraries were prepared with Illumina DNA Prep and sequenced using the MiniSeq platform. Genome assemblies enabled multilocus sequence typing and ospC typing.
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Affiliation(s)
- Thomas H. Haidl
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
- Department of Biology, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
| | - Min-Kuang Lee
- Zoonotic Diseases & Emerging Pathogens, BC Centre for Disease Control-Public Health Laboratory, Vancouver, British Columbia, Canada
| | - Sean D. Workman
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
- Department of Biology, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
| | - Jennifer N. Russell
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
- Department of Biology, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
| | - Erin Fraser
- BC Centre for Disease Control, Vancouver, British Columbia, Canada
- School of Population & Public Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Muhammad G. Morshed
- Zoonotic Diseases & Emerging Pathogens, BC Centre for Disease Control-Public Health Laboratory, Vancouver, British Columbia, Canada
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andrew D. S. Cameron
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
- Department of Biology, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
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3
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Kröger C, Lerminiaux NA, Ershova AS, MacKenzie KD, Kirzinger MW, Märtlbauer E, Perry BJ, Cameron ADS, Schauer K. Plasmid-encoded lactose metabolism and mobilized colistin resistance ( mcr-9) genes in Salmonella enterica serovars isolated from dairy facilities in the 1980s. Microb Genom 2023; 9. [PMID: 38031909 DOI: 10.1099/mgen.0.001149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023] Open
Abstract
Horizontal gene transfer by plasmids can confer metabolic capabilities that expand a host cell's niche. Yet, it is less understood whether the coalescence of specialized catabolic functions, antibiotic resistances and metal resistances on plasmids provides synergistic benefits. In this study, we report whole-genome assembly and phenotypic analysis of five Salmonella enterica strains isolated in the 1980s from milk powder in Munich, Germany. All strains exhibited the unusual phenotype of lactose-fermentation and encoded either of two variants of the lac operon. Surprisingly, all strains encoded the mobilized colistin resistance gene 9 (mcr-9), long before the first report of this gene in the literature. In two cases, the mcr-9 gene and the lac locus were linked within a large gene island that formed an IncHI2A-type plasmid in one strain but was chromosomally integrated in the other strain. In two other strains, the mcr-9 gene was found on a large IncHI1B/IncP-type plasmid, whereas the lac locus was encoded on a separate chromosomally integrated plasmidic island. The mcr-9 sequences were identical and genomic contexts could not explain the wide range of colistin resistances exhibited by the Salmonella strains. Nucleotide variants did explain phenotypic differences in motility and exopolysaccharide production. The observed linkage of mcr-9 to lactose metabolism, an array of heavy-metal detoxification systems, and other antibiotic resistance genes may reflect a coalescence of specialized phenotypes that improve the spread of colistin resistance in dairy facilities, much earlier than previously suspected.
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Affiliation(s)
- Carsten Kröger
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Nicole A Lerminiaux
- Department of Biology, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
| | - Anna S Ershova
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Keith D MacKenzie
- Department of Biology, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
| | - Morgan W Kirzinger
- Department of Biology, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
- Present address: National Research Council Canada, Saskatoon, Saskatchewan, S7N 0W9, Canada
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, Oberschleißheim, 85764, Germany
| | - Benjamin J Perry
- Department of Biology, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
- Present address: AgResearch, 176 Puddle Alley, Mosgiel 9092, New Zealand
| | - Andrew D S Cameron
- Department of Biology, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, S4S 0A2, Canada
| | - Kristina Schauer
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, Oberschleißheim, 85764, Germany
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4
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Zinck CB, Raveendram Thampy P, Uhlemann EME, Adam H, Wachter J, Suchan D, Cameron ADS, Rego ROM, Brisson D, Bouchard C, Ogden NH, Voordouw MJ. Variation among strains of Borrelia burgdorferi in host tissue abundance and lifetime transmission determine the population strain structure in nature. PLoS Pathog 2023; 19:e1011572. [PMID: 37607182 PMCID: PMC10473547 DOI: 10.1371/journal.ppat.1011572] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 09/01/2023] [Accepted: 07/23/2023] [Indexed: 08/24/2023] Open
Abstract
Pathogen life history theory assumes a positive relationship between pathogen load in host tissues and pathogen transmission. Empirical evidence for this relationship is surprisingly rare due to the difficulty of measuring transmission for many pathogens. The comparative method, where a common host is experimentally infected with a set of pathogen strains, is a powerful approach for investigating the relationships between pathogen load and transmission. The validity of such experimental estimates of strain-specific transmission is greatly enhanced if they can predict the pathogen population strain structure in nature. Borrelia burgdorferi is a multi-strain, tick-borne spirochete that causes Lyme disease in North America. This study used 11 field-collected strains of B. burgdorferi, a rodent host (Mus musculus, C3H/HeJ) and its tick vector (Ixodes scapularis) to determine the relationship between pathogen load in host tissues and lifetime host-to-tick transmission (HTT). Mice were experimentally infected via tick bite with 1 of 11 strains. Lifetime HTT was measured by infesting mice with I. scapularis larval ticks on 3 separate occasions. The prevalence and abundance of the strains in the mouse tissues and the ticks were determined by qPCR. We used published databases to obtain estimates of the frequencies of these strains in wild I. scapularis tick populations. Spirochete loads in ticks and lifetime HTT varied significantly among the 11 strains of B. burgdorferi. Strains with higher spirochete loads in the host tissues were more likely to infect feeding larval ticks, which molted into nymphal ticks that had a higher probability of B. burgdorferi infection (i.e., higher HTT). Our laboratory-based estimates of lifetime HTT were predictive of the frequencies of these strains in wild I. scapularis populations. For B. burgdorferi, the strains that establish high abundance in host tissues and that have high lifetime transmission are the strains that are most common in nature.
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Affiliation(s)
- Christopher B. Zinck
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Prasobh Raveendram Thampy
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Eva-Maria E. Uhlemann
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Hesham Adam
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jenny Wachter
- Vaccine and Infectious Disease Organization, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Danae Suchan
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
- Department of Biology, University of Regina, Regina, Saskatchewan, Canada
| | - Andrew D. S. Cameron
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, Saskatchewan, Canada
- Department of Biology, University of Regina, Regina, Saskatchewan, Canada
| | - Ryan O. M. Rego
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, České Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Dustin Brisson
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Catherine Bouchard
- Public Health Risk Sciences, National Microbiology Laboratory, Public Health Agency of Canada, St Hyacinthe, Quebec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Montreal, Canada
| | - Nicholas H. Ogden
- Public Health Risk Sciences, National Microbiology Laboratory, Public Health Agency of Canada, St Hyacinthe, Quebec, Canada
- Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculté de Médecine Vétérinaire, Université de Montréal, Montreal, Canada
- Centre de recherche en santé publique (CReSP), Université de Montréal, Montreal, QC, Canada
| | - Maarten J. Voordouw
- Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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5
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Brown-Elliott BA, Wallace RJ, Wengenack NL, Workman SD, Cameron ADS, Bush G, Hughes MD, Melton S, Gonzalez-Ramirez B, Rodriguez E, Somayaji K, Klapperich C, Viers M, Bolaji AJ, Rempel E, Alexander DC. Emergence of Inducible Macrolide Resistance in Mycobacterium chelonae Due to Broad-Host-Range Plasmid and Chromosomal Variants of the Novel 23S rRNA Methylase Gene, erm(55). J Clin Microbiol 2023; 61:e0042823. [PMID: 37347171 PMCID: PMC10358161 DOI: 10.1128/jcm.00428-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 05/31/2023] [Indexed: 06/23/2023] Open
Abstract
Macrolides are a mainstay of therapy for infections due to nontuberculous mycobacteria (NTM). Among rapidly growing mycobacteria (RGM), inducible macrolide resistance is associated with four chromosomal 23S rRNA methylase (erm) genes. Beginning in 2018, we detected high-level inducible clarithromycin resistance (MICs of ≥16μg/mL) in clinical isolates of Mycobacterium chelonae, an RGM species not previously known to contain erm genes. Using whole-genome sequencing, we identified a novel plasmid-mediated erm gene. This gene, designated erm(55)P, exhibits <65% amino acid identity to previously described RGM erm genes. Two additional chromosomal erm(55) alleles, with sequence identities of 81% to 86% to erm(55)P, were also identified and designated erm(55)C and erm(55)T. The erm(55)T is part of a transposon. The erm(55)P allele variant is located on a putative 137-kb conjugative plasmid, pMchErm55. Evaluation of 133 consecutive isolates from 2020 to 2022 revealed 5 (3.8%) with erm(55). The erm(55)P gene was also identified in public data sets of two emerging pathogenic pigmented RGM species: Mycobacterium iranicum and Mycobacterium obuense, dating back to 2008. In both species, the gene appeared to be present on plasmids homologous to pMchErm55. Plasmid-mediated macrolide resistance, not described previously for any NTM species, appears to have spread to multiple RGM species. This has important implications for antimicrobial susceptibility guidelines and treatment of RGM infections. Further spread could present serious consequences for treatment of other macrolide-susceptible RGM. Additional studies are needed to determine the transmissibility of pMchErm55 and the distribution of erm(55) among other RGM species.
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Affiliation(s)
- Barbara A. Brown-Elliott
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - Richard J. Wallace
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - Nancy L. Wengenack
- Division of Clinical Microbiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sean D. Workman
- Department of Biology, University of Regina, Regina, Saskatchewan, Canada
| | | | - Georgie Bush
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - M. Dolores Hughes
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - Stephanie Melton
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - Bibiana Gonzalez-Ramirez
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - Eliana Rodriguez
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | - Kavya Somayaji
- Mycobacteria/Nocardia Research Laboratory, University of Texas Health Science Center at Tyler, Tyler, Texas, USA
| | | | - Mary Viers
- Division of Clinical Microbiology, Mayo Clinic, Rochester, Minnesota, USA
| | - Ayooluwa J. Bolaji
- Cadham Provincial Laboratory, Diagnostic Services, Shared Health, Winnipeg, Manitoba, Canada
| | - Emma Rempel
- Cadham Provincial Laboratory, Diagnostic Services, Shared Health, Winnipeg, Manitoba, Canada
| | - David C. Alexander
- Cadham Provincial Laboratory, Diagnostic Services, Shared Health, Winnipeg, Manitoba, Canada
- Department of Medical Microbiology and Infectious Diseases, University of Manitoba, Winnipeg, Canada
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6
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Nowlan JP, Sies AN, Britney SR, Cameron ADS, Siah A, Lumsden JS, Russell S. Genomics of Tenacibaculum Species in British Columbia, Canada. Pathogens 2023; 12:pathogens12010101. [PMID: 36678448 PMCID: PMC9864904 DOI: 10.3390/pathogens12010101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/30/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Tenacibaculum is a genus of Gram-negative filamentous bacteria with a cosmopolitan distribution. The research describing Tenacibaculum genomes stems primarily from Norway and Chile due to their impacts on salmon aquaculture. Canadian salmon aquaculture also experiences mortality events related to the presence of Tenacibaculum spp., yet no Canadian Tenacibaculum genomes are publicly available. Ribosomal DNA sequencing of 16S and four species-specific 16S quantitative-PCR assays were used to select isolates cultured from Atlantic salmon with mouthrot in British Columbia (BC), Canada. Ten isolates representing four known and two unknown species of Tenacibaculum were selected for shotgun whole genome sequencing using the Oxford Nanopore's MinION platform. The genome assemblies achieved closed circular chromosomes for seven isolates and long contigs for the remaining three isolates. Average nucleotide identity analysis identified T. ovolyticum, T. maritimum, T. dicentrarchi, two genomovars of T. finnmarkense, and two proposed novel species T. pacificus sp. nov. type strain 18-2881-AT and T. retecalamus sp. nov. type strain 18-3228-7BT. Annotation in most of the isolates predicted putative virulence and antimicrobial resistance genes, most-notably toxins (i.e., hemolysins), type-IX secretion systems, and oxytetracycline resistance. Comparative analysis with the T. maritimum type-strain predicted additional toxins and numerous C-terminal secretion proteins, including an M12B family metalloprotease in the T. maritimum isolates from BC. The genomic prediction of virulence-associated genes provides important targets for studies of mouthrot disease, and the annotation of the antimicrobial resistance genes provides targets for surveillance and diagnosis in veterinary medicine.
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Affiliation(s)
- Joseph P. Nowlan
- Center for Innovation in Fish Health, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada
- Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1, Canada
- Correspondence:
| | - Ashton N. Sies
- Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Scott R. Britney
- Center for Innovation in Fish Health, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada
- Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Andrew D. S. Cameron
- Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Ahmed Siah
- BC Center for Aquatic Health Sciences, Campbell River, BC V9W 2C2, Canada
| | - John S. Lumsden
- Department of Pathobiology, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Spencer Russell
- Center for Innovation in Fish Health, Vancouver Island University, Nanaimo, BC V9R 5S5, Canada
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7
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Bhat SV, Maughan H, Cameron ADS, Yost CK. Phylogenomic analysis of the genus Delftia reveals distinct major lineages with ecological specializations. Microb Genom 2022; 8:mgen000864. [PMID: 36107145 PMCID: PMC9676026 DOI: 10.1099/mgen.0.000864] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Accepted: 06/15/2022] [Indexed: 04/01/2024] Open
Abstract
Delftia is a diverse betaproteobacterial genus with many strains having agricultural and industrial relevance, including plant-growth promotion, bioremediation of hydrocarbon-contaminated soils, and heavy metal immobilization. Delftia spp. are broadly distributed in the environment, and have been isolated from plant hosts as well as healthy and diseased animal hosts, yet the genetic basis of this ecological versatility has not been characterized. Here, we present a phylogenomic comparison of published Delftia genomes and show that the genus is divided into two well-supported clades: one 'Delftia acidovorans' clade with isolates from soils and plant rhizospheres, and a second 'Delftia lacustris and Delftia tsuruhatensis' clade with isolates from humans and sludge. The pan-genome inferred from 61 Delftia genomes contained over 28 000 genes, of which only 884 were found in all genomes. Analysis of industrially relevant functions highlighted the ecological versatility of Delftia and supported their role as generalists.
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Affiliation(s)
- Supriya V. Bhat
- Department of Biology, University of Regina, Regina, SK, Canada
- Institute for Microbial Systems and Society, University of Regina, Regina, SK, Canada
| | | | - Andrew D. S. Cameron
- Department of Biology, University of Regina, Regina, SK, Canada
- Institute for Microbial Systems and Society, University of Regina, Regina, SK, Canada
| | - Christopher K. Yost
- Department of Biology, University of Regina, Regina, SK, Canada
- Institute for Microbial Systems and Society, University of Regina, Regina, SK, Canada
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8
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Amin MR, Korchinski L, Yoneda JK, Thakkar R, Sanson CLA, Fitzgerald SF, Kelln RA, Cameron ADS. A mutation in the putative CRP binding site of the dctA promoter of Salmonella enterica serovar Typhimurium enables growth with low orotate concentrations. Can J Microbiol 2022; 68:615-621. [PMID: 35921682 DOI: 10.1139/cjm-2022-0120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Salmonella enterica and Escherichia coli use the inner membrane transporter DctA to import the pyrimidine biosynthetic pathway intermediate orotate from the environment. To study the regulation of dctA expression, we used a S. enterica serovar Typhimurium pyrimidine auxotroph to select a mutant that could grow in an otherwise non-permissive culture medium containing glucose and a low concentration of orotate. Whole genome sequencing revealed a point mutation upstream of dctA in the putative cyclic AMP receptor protein (CRP) binding site. The C->T transition converted the least-favourable base to the most-favourable base for CRP-DNA affinity. A dctA::lux transcriptional fusion confirmed that the mutant dctA promoter gained responsiveness to CRP even in the presence of glucose. Moreover, dctA expression was higher in the mutant than the wild type in the presence of alternative carbon sources that activate CRP.
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Affiliation(s)
- Mohammad R Amin
- University of Regina, 6846, Department of Biology, Regina, Saskatchewan, Canada.,University of Regina, 6846, Institute for Microbial Systems and Society, Regina, Saskatchewan, Canada;
| | - Lisa Korchinski
- University of Regina, 6846, Department of Chemistry and Biochemistry, Regina, Saskatchewan, Canada;
| | - Joshua K Yoneda
- University of Regina, 6846, Department of Biology, Regina, Saskatchewan, Canada.,University of Regina, 6846, Institute for Microbial Systems and Society, Regina, Saskatchewan, Canada;
| | - Rishi Thakkar
- University of Regina, 6846, Department of Biology, Regina, Saskatchewan, Canada.,University of Regina, 6846, Institute for Microbial Systems and Society, Regina, Saskatchewan, Canada;
| | - Carla L A Sanson
- University of Regina, 6846, Department of Chemistry and Biochemistry, Regina, Saskatchewan, Canada.,Government of Saskatchewan Ministry of Labour Relations and Workplace Safety, 359189, Occupational Health and Safety Branch, Regina, Saskatchewan, Canada;
| | - Stephen F Fitzgerald
- University of Regina, 6846, Department of Biology, Regina, Saskatchewan, Canada.,Moredun Research Institute, 6485, Penicuik, United Kingdom of Great Britain and Northern Ireland;
| | - Rod A Kelln
- University of Regina, 6846, Department of Chemistry and Biochemistry, Regina, Saskatchewan, Canada;
| | - Andrew D S Cameron
- University of Regina, 6846, Department of Biology, Regina, Saskatchewan, Canada.,University of Regina, 6846, Institute for Microbial Systems and Society, Regina, Saskatchewan, Canada;
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9
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Ramsay JP, Bastholm TR, Verdonk CJ, Tambalo DD, Sullivan JT, Harold LK, Panganiban BA, Colombi E, Perry BJ, Jowsey W, Morris C, Hynes MF, Bond CS, Cameron ADS, Yost CK, Ronson CW. An epigenetic switch activates bacterial quorum sensing and horizontal transfer of an integrative and conjugative element. Nucleic Acids Res 2021; 50:975-988. [PMID: 34904658 PMCID: PMC8789080 DOI: 10.1093/nar/gkab1217] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 11/23/2021] [Accepted: 11/25/2021] [Indexed: 11/13/2022] Open
Abstract
Horizontal transfer of the integrative and conjugative element ICEMlSymR7A converts non-symbiotic Mesorhizobium spp. into nitrogen-fixing legume symbionts. Here, we discover subpopulations of Mesorhizobium japonicum R7A become epigenetically primed for quorum-sensing (QS) and QS-activated horizontal transfer. Isolated populations in this state termed R7A* maintained these phenotypes in laboratory culture but did not transfer the R7A* state to recipients of ICEMlSymR7A following conjugation. We previously demonstrated ICEMlSymR7A transfer and QS are repressed by the antiactivator QseM in R7A populations and that the adjacently-coded DNA-binding protein QseC represses qseM transcription. Here RNA-sequencing revealed qseM expression was repressed in R7A* cells and that RNA antisense to qseC was abundant in R7A but not R7A*. Deletion of the antisense-qseC promoter converted cells into an R7A*-like state. An adjacently coded QseC2 protein bound two operator sites and repressed antisense-qseC transcription. Plasmid overexpression of QseC2 stimulated the R7A* state, which persisted following curing of this plasmid. The epigenetic maintenance of the R7A* state required ICEMlSymR7A-encoded copies of both qseC and qseC2. Therefore, QseC and QseC2, together with their DNA-binding sites and overlapping promoters, form a stable epigenetic switch that establishes binary control over qseM transcription and primes a subpopulation of R7A cells for QS and horizontal transfer.
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Affiliation(s)
- Joshua P Ramsay
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Tahlia R Bastholm
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Callum J Verdonk
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia.,Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Dinah D Tambalo
- Biology Department, University of Regina, Regina, SK S4S 0A2, Canada
| | - John T Sullivan
- Department of Microbiology and Immunology, University of Otago, Dunedin, 9016, New Zealand
| | - Liam K Harold
- Department of Microbiology and Immunology, University of Otago, Dunedin, 9016, New Zealand
| | - Beatrice A Panganiban
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Elena Colombi
- Curtin Medical School and Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Benjamin J Perry
- Department of Microbiology and Immunology, University of Otago, Dunedin, 9016, New Zealand
| | - William Jowsey
- Department of Microbiology and Immunology, University of Otago, Dunedin, 9016, New Zealand
| | - Calum Morris
- Department of Microbiology and Immunology, University of Otago, Dunedin, 9016, New Zealand
| | - Michael F Hynes
- Department of Biological Sciences, University of Calgary, Calgary, AB T2N 4V8, Canada
| | - Charles S Bond
- School of Molecular Sciences, University of Western Australia, Perth, WA 6009, Australia
| | | | | | - Clive W Ronson
- Department of Microbiology and Immunology, University of Otago, Dunedin, 9016, New Zealand
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10
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Kumar A, Cameron ADS, Zilles S. Machine Learning to Identify Gene Interactions from High-Throughput Mutant Crosses. Methods Mol Biol 2021; 2381:217-223. [PMID: 34590279 DOI: 10.1007/978-1-0716-1740-3_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Advances in molecular genetics through high-throughput gene mutagenesis and genetic crossing have enabled gene interaction mapping across whole genomes. Detecting gene interactions in even small microbial genomes relies on measuring growth phenotypes in thousands of crossed strains followed by statistical analysis to compare single and double mutants. The preferred computational approach is to use a multiplicative model that factors phenotype scores of single gene mutants to identify gene interactions in double mutants. Here we present how machine learning models that consider the characteristics of the phenotypic data improve on the classical multiplicative model. Importantly, machine learning improves the selection of cutoff values to identify gene interactions from phenotypic scores.
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Affiliation(s)
- Ashwani Kumar
- Department of Computer Science, University of Regina, Regina, SK, Canada.
| | | | - Sandra Zilles
- Department of Computer Science, University of Regina, Regina, SK, Canada.
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11
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Bottos EM, Al-Shabib EY, Shaw DMJ, McAmmond BM, Sharma A, Suchan DM, Cameron ADS, Van Hamme JD. Transcriptomic response of Gordonia sp. strain NB4-1Y when provided with 6:2 fluorotelomer sulfonamidoalkyl betaine or 6:2 fluorotelomer sulfonate as sole sulfur source. Biodegradation 2020; 31:407-422. [PMID: 33150552 PMCID: PMC7661421 DOI: 10.1007/s10532-020-09917-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 10/27/2020] [Indexed: 02/06/2023]
Abstract
Abstract Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are environmental contaminants of concern. We previously described biodegradation of two PFAS that represent components and transformation products of aqueous film-forming foams (AFFF), 6:2 fluorotelomer sulfonamidoalkyl betaine (6:2 FTAB) and 6:2 fluorotelomer sulfonate (6:2 FTSA), by Gordonia sp. strain NB4-1Y. To identify genes involved in the breakdown of these compounds, the transcriptomic response of NB4-1Y was examined when grown on 6:2 FTAB, 6:2 FTSA, a non-fluorinated analog of 6:2 FTSA (1-octanesulfonate), or MgSO4, as sole sulfur source. Differentially expressed genes were identified as those with ± 1.5 log2-fold-differences (± 1.5 log2FD) in transcript abundances in pairwise comparisons. Transcriptomes of cells grown on 6:2 FTAB and 6:2 FTSA were most similar (7.9% of genes expressed ± 1.5 log2FD); however, several genes that were expressed in greater abundance in 6:2 FTAB treated cells compared to 6:2 FTSA treated cells were noted for their potential role in carbon–nitrogen bond cleavage in 6:2 FTAB. Responses to sulfur limitation were observed in 6:2 FTAB, 6:2 FTSA, and 1-octanesulfonate treatments, as 20 genes relating to global sulfate stress response were more highly expressed under these conditions compared to the MgSO4 treatment. More highly expressed oxygenase genes in 6:2 FTAB, 6:2 FTSA, and 1-octanesulfonate treatments were found to code for proteins with lower percent sulfur-containing amino acids compared to both the total proteome and to oxygenases showing decreased expression. This work identifies genetic targets for further characterization and will inform studies aimed at evaluating the biodegradation potential of environmental samples through applied genomics. Graphic Abstract ![]()
Electronic supplementary material The online version of this article (10.1007/s10532-020-09917-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Eric M Bottos
- Department of Biological Sciences, Thompson Rivers University, Kamloops, BC, V2C 0C8, Canada
| | - Ebtihal Y Al-Shabib
- Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada
- Faculty of Science, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Dayton M J Shaw
- Department of Biological Sciences, Thompson Rivers University, Kamloops, BC, V2C 0C8, Canada
| | - Breanne M McAmmond
- Department of Biological Sciences, Thompson Rivers University, Kamloops, BC, V2C 0C8, Canada
| | - Aditi Sharma
- Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada
- Faculty of Science, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Danae M Suchan
- Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada
- Faculty of Science, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Andrew D S Cameron
- Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada
- Faculty of Science, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Jonathan D Van Hamme
- Department of Biological Sciences, Thompson Rivers University, Kamloops, BC, V2C 0C8, Canada.
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12
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Fitzgerald S, Kary SC, Alshabib EY, MacKenzie KD, Stoebel DM, Chao TC, Cameron ADS. Redefining the H-NS protein family: a diversity of specialized core and accessory forms exhibit hierarchical transcriptional network integration. Nucleic Acids Res 2020; 48:10184-10198. [PMID: 32894292 PMCID: PMC7544231 DOI: 10.1093/nar/gkaa709] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/07/2020] [Accepted: 08/23/2020] [Indexed: 12/27/2022] Open
Abstract
H-NS is a nucleoid structuring protein and global repressor of virulence and horizontally-acquired genes in bacteria. H-NS can interact with itself or with homologous proteins, but protein family diversity and regulatory network overlap remain poorly defined. Here, we present a comprehensive phylogenetic analysis that revealed deep-branching clades, dispelling the presumption that H-NS is the progenitor of varied molecular backups. Each clade is composed exclusively of either chromosome-encoded or plasmid-encoded proteins. On chromosomes, stpA and newly discovered hlpP are core genes in specific genera, whereas hfp and newly discovered hlpC are sporadically distributed. Six clades of H-NS plasmid proteins (Hpp) exhibit ancient and dedicated associations with plasmids, including three clades with fidelity for plasmid incompatibility groups H, F or X. A proliferation of H-NS homologs in Erwiniaceae includes the first observation of potentially co-dependent H-NS forms. Conversely, the observed diversification of oligomerization domains may facilitate stable co-existence of divergent homologs in a genome. Transcriptomic and proteomic analysis in Salmonella revealed regulatory crosstalk and hierarchical control of H-NS homologs. We also discovered that H-NS is both a repressor and activator of Salmonella Pathogenicity Island 1 gene expression, and both regulatory modes are restored by Sfh (HppH) in the absence of H-NS.
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Affiliation(s)
- Stephen Fitzgerald
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.,Division of Immunity and Infection, The Roslin Institute and R(D)SVS, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Stefani C Kary
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Ebtihal Y Alshabib
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.,Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Keith D MacKenzie
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.,Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Daniel M Stoebel
- Department of Biology, Harvey Mudd College, Claremont, CA 91711, USA
| | - Tzu-Chiao Chao
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.,Institute of Environmental Change and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Andrew D S Cameron
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada.,Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
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13
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Lerminiaux NA, MacKenzie KD, Cameron ADS. Salmonella Pathogenicity Island 1 (SPI-1): The Evolution and Stabilization of a Core Genomic Type Three Secretion System. Microorganisms 2020; 8:microorganisms8040576. [PMID: 32316180 PMCID: PMC7232297 DOI: 10.3390/microorganisms8040576] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 04/10/2020] [Accepted: 04/10/2020] [Indexed: 11/16/2022] Open
Abstract
Salmonella Pathogenicity Island 1 (SPI-1) encodes a type three secretion system (T3SS), effector proteins, and associated transcription factors that together enable invasion of epithelial cells in animal intestines. The horizontal acquisition of SPI-1 by the common ancestor of all Salmonella is considered a prime example of how gene islands potentiate the emergence of new pathogens with expanded niche ranges. However, the evolutionary history of SPI-1 has attracted little attention. Here, we apply phylogenetic comparisons across the family Enterobacteriaceae to examine the history of SPI-1, improving the resolution of its boundaries and unique architecture by identifying its composite gene modules. SPI-1 is located between the core genes fhlA and mutS, a hotspot for the gain and loss of horizontally acquired genes. Despite the plasticity of this locus, SPI-1 demonstrates stable residency of many tens of millions of years in a host genome, unlike short-lived homologous T3SS and effector islands including Escherichia ETT2, Yersinia YSA, Pantoea PSI-2, Sodalis SSR2, and Chromobacterium CPI-1. SPI-1 employs a unique series of regulatory switches, starting with the dedicated transcription factors HilC and HilD, and flowing through the central SPI-1 regulator HilA. HilA is shared with other T3SS, but HilC and HilD may have their evolutionary origins in Salmonella. The hilA, hilC, and hilD gene promoters are the most AT-rich DNA in SPI-1, placing them under tight control by the transcriptional repressor H-NS. In all Salmonella lineages, these three promoters resist amelioration towards the genomic average, ensuring strong repression by H-NS. Hence, early development of a robust and well-integrated regulatory network may explain the evolutionary stability of SPI-1 compared to T3SS gene islands in other species.
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Affiliation(s)
- Nicole A. Lerminiaux
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Keith D. MacKenzie
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Andrew D. S. Cameron
- Department of Biology, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada; (N.A.L.); (K.D.M.)
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
- Correspondence:
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14
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Bergsveinson J, Perry BJ, Simpson GL, Yost CK, Schutzman RJ, Hall BD, Cameron ADS. Spatial analysis of a hydrocarbon waste-remediating landfarm demonstrates influence of management practices on bacterial and fungal community structure. Microb Biotechnol 2019; 12:1199-1209. [PMID: 30927344 PMCID: PMC6801160 DOI: 10.1111/1751-7915.13397] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 02/15/2019] [Accepted: 02/21/2019] [Indexed: 11/27/2022] Open
Abstract
Cultivation of dedicated soil plots called 'landfarms' is an effective technology for bioremediation of hydrocarbon waste generated by various industrial practices. To understand the influence of soil conditions on landfarm microbial communities, analysis of bacterial and fungal community structure using next-generation sequencing at different sections and depths was performed across a hydrocarbon-waste landfarm in Regina, Saskatchewan, Canada. While a core set of hydrocarbon-associated bacterial and fungal taxa are present throughout the landfarm, unique bacterial and fungal operational taxonomic units are differentially abundant at sections within the landfarm, which correlate with differences in soil physiochemical properties and management practices. Increased frequency of waste application resulted in strong positive correlations between bacterial community assemblages and elevated amounts of oil, grease and F3 - F4 hydrocarbon fractions. In areas of standing water and lower application of hydrocarbon, microbial community structure correlated with soil pH, trace nutrients and metals. Overall, diversity and structure of bacterial communities remain relatively stable across the landfarm, while in contrast, fungal community structure appears more responsive to soil oxygen conditions. Results are consistent with the hypothesis that years of bioremediation activity have shaped microbial communities; however, several management practices can be undertaken to increase efficiency of remediation, including the removal of standing water and soil tilling across the landfarm.
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Affiliation(s)
- Jordyn Bergsveinson
- Department of BiologyUniversity of ReginaReginaSKCanada
- Institute for Microbial Systems and SocietyUniversity of ReginaReginaSKCanada
| | - Benjamin J. Perry
- Department of BiologyUniversity of ReginaReginaSKCanada
- Present address:
Department of Microbiology and ImmunologyUniversity of OtagoDunedinNew Zealand
| | - Gavin L. Simpson
- Department of BiologyUniversity of ReginaReginaSKCanada
- Institute of Environmental Change and SocietyUniversity of ReginaReginaSKCanada
| | - Christopher K. Yost
- Department of BiologyUniversity of ReginaReginaSKCanada
- Institute for Microbial Systems and SocietyUniversity of ReginaReginaSKCanada
| | | | - Britt D. Hall
- Department of BiologyUniversity of ReginaReginaSKCanada
| | - Andrew D. S. Cameron
- Department of BiologyUniversity of ReginaReginaSKCanada
- Institute for Microbial Systems and SocietyUniversity of ReginaReginaSKCanada
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15
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Lande L, Alexander DC, Wallace RJ, Kwait R, Iakhiaeva E, Williams M, Cameron ADS, Olshefsky S, Devon R, Vasireddy R, Peterson DD, Falkinham JO. Mycobacterium avium in Community and Household Water, Suburban Philadelphia, Pennsylvania, USA, 2010-2012. Emerg Infect Dis 2019; 25:473-481. [PMID: 30789130 PMCID: PMC6390762 DOI: 10.3201/eid2503.180336] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Attention to environmental sources of Mycobacterium avium complex (MAC) infection is a vital component of disease prevention and control. We investigated MAC colonization of household plumbing in suburban Philadelphia, Pennsylvania, USA. We used variable-number tandem-repeat genotyping and whole-genome sequencing with core genome single-nucleotide variant analysis to compare M. avium from household plumbing biofilms with M. avium isolates from patient respiratory specimens. M. avium was recovered from 30 (81.1%) of 37 households, including 19 (90.5%) of 21 M. avium patient households. For 11 (52.4%) of 21 patients with M. avium disease, isolates recovered from their respiratory and household samples were of the same genotype. Within the same community, 18 (85.7%) of 21 M. avium respiratory isolates genotypically matched household plumbing isolates. Six predominant genotypes were recovered across multiple households and respiratory specimens. M. avium colonizing municipal water and household plumbing may be a substantial source of MAC pulmonary infection.
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16
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Kröger C, MacKenzie KD, Alshabib EY, Kirzinger MWB, Suchan DM, Chao TC, Akulova V, Miranda-CasoLuengo AA, Monzon VA, Conway T, Sivasankaran SK, Hinton JCD, Hokamp K, Cameron ADS. The primary transcriptome, small RNAs and regulation of antimicrobial resistance in Acinetobacter baumannii ATCC 17978. Nucleic Acids Res 2018; 46:9684-9698. [PMID: 29986115 PMCID: PMC6182133 DOI: 10.1093/nar/gky603] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 06/21/2018] [Accepted: 06/26/2018] [Indexed: 12/12/2022] Open
Abstract
We present the first high-resolution determination of transcriptome architecture in the priority pathogen Acinetobacter baumannii. Pooled RNA from 16 laboratory conditions was used for differential RNA-seq (dRNA-seq) to identify 3731 transcriptional start sites (TSS) and 110 small RNAs, including the first identification in A. baumannii of sRNAs encoded at the 3' end of coding genes. Most sRNAs were conserved among sequenced A. baumannii genomes, but were only weakly conserved or absent in other Acinetobacter species. Single nucleotide mapping of TSS enabled prediction of -10 and -35 RNA polymerase binding sites and revealed an unprecedented base preference at position +2 that hints at an unrecognized transcriptional regulatory mechanism. To apply functional genomics to the problem of antimicrobial resistance, we dissected the transcriptional regulation of the drug efflux pump responsible for chloramphenicol resistance, craA. The two craA promoters were both down-regulated >1000-fold when cells were shifted to nutrient limited medium. This conditional down-regulation of craA expression renders cells sensitive to chloramphenicol, a highly effective antibiotic for the treatment of multidrug resistant infections. An online interface that facilitates open data access and visualization is provided as 'AcinetoCom' (http://bioinf.gen.tcd.ie/acinetocom/).
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Affiliation(s)
- Carsten Kröger
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Keith D MacKenzie
- Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Ebtihal Y Alshabib
- Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Morgan W B Kirzinger
- Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Danae M Suchan
- Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Tzu-Chiao Chao
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
- Institute of Environmental Change and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Valentyna Akulova
- Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
| | - Aleksandra A Miranda-CasoLuengo
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Vivian A Monzon
- Department of Microbiology, School of Genetics & Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Tyrrell Conway
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Sathesh K Sivasankaran
- John P. Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Jay C D Hinton
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, UK
| | - Karsten Hokamp
- Department of Genetics, School of Genetics & Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland
| | - Andrew D S Cameron
- Institute for Microbial Systems and Society, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
- Department of Biology, University of Regina, Regina, Saskatchewan S4S 0A2, Canada
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17
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Abstract
A global medical crisis is unfolding as antibiotics lose effectiveness against a growing number of bacterial pathogens. Horizontal gene transfer (HGT) contributes significantly to the rapid spread of resistance, yet the transmission dynamics of genes that confer antibiotic resistance are poorly understood. Multiple mechanisms of HGT liberate genes from normal vertical inheritance. Conjugation by plasmids, transduction by bacteriophages, and natural transformation by extracellular DNA each allow genetic material to jump between strains and species. Thus, HGT adds an important dimension to infectious disease whereby an antibiotic resistance gene (ARG) can be the agent of an outbreak by transferring resistance to multiple unrelated pathogens. Here, we review the small number of cases where HGT has been detected in clinical environments. We discuss differences and synergies between the spread of plasmid-borne and chromosomal ARGs, with a special consideration of the difficulties of detecting transduction and transformation by routine genetic diagnostics. We highlight how 11 of the top 12 priority antibiotic-resistant pathogens are known or predicted to be naturally transformable, raising the possibility that this mechanism of HGT makes significant contributions to the spread of ARGs. HGT drives the evolution of untreatable "superbugs" by concentrating ARGs together in the same cell, thus HGT must be included in strategies to prevent the emergence of resistant organisms in hospitals and other clinical settings.
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Affiliation(s)
| | - Andrew D S Cameron
- a Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada.,b Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK S4S 0A2, Canada
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18
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Sanderson CE, Fox JT, Dougherty ER, Cameron ADS, Alexander KA. The Changing Face of Water: A Dynamic Reflection of Antibiotic Resistance Across Landscapes. Front Microbiol 2018; 9:1894. [PMID: 30237787 PMCID: PMC6135886 DOI: 10.3389/fmicb.2018.01894] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 07/27/2018] [Indexed: 11/13/2022] Open
Abstract
Little is known about the role of surface water in the propagation of antibiotic resistance (AR), or the relationship between AR and water quality declines. While healthcare and agricultural sectors are considered the main contributors to AR dissemination, few studies have been conducted in their absence. Using linear models and Bayesian kriging, we evaluate AR among Escherichia coli water isolates collected bimonthly from the Chobe River in Northern Botswana (n = 1997, n = 414 water samples; July 2011-May 2012) in relation to water quality dynamics (E. coli, fecal coliform, and total suspended solids), land use, season, and AR in wildlife and humans within this system. No commercial agricultural or large medical facilities exist within this region. Here, we identify widespread AR in surface water, with land use and season significant predicators of AR levels. Mean AR was significantly higher in the wet season than the dry season (p = 0.003), and highest in the urban landscape (2.15, SD = 0.098) than the protected landscape (1.39, SD = 0.051). In-water E. coli concentrations were significantly positively associated with mean AR in the wet season (p < 0.001) but not in the dry season (p = 0.110), with TSS negatively associated with mean AR across seasons (p = 0.016 and p = 0.029), identifying temporal and spatial relationships between water quality variables and AR. Importantly, when human, water, and wildlife isolates were examined, similar AR profiles were identified (p < 0.001). Our results suggest that direct human inputs are sufficient for extensive dispersal of AR into the environment, with landscape features, season, and water quality variables influencing AR dynamics. Focused and expensive efforts to minimize pollution from agricultural sources, while important, may only provide incremental benefits to the management of AR across complex landscapes. Controlling direct human AR inputs into the environment remains a critical and pressing challenge.
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Affiliation(s)
- Claire E. Sanderson
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, United States
- Center for African Resources: Animals, Communities and Land Use, Kasane, Botswana
| | - J. Tyler Fox
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, United States
- Center for African Resources: Animals, Communities and Land Use, Kasane, Botswana
| | - Eric R. Dougherty
- Department of Environmental Science, Policy, and Management, University of California at Berkeley, Berkeley, CA, United States
| | - Andrew D. S. Cameron
- Institute for Microbial Systems and Society, Faculty of Science, University of Regina, Regina, SK, Canada
- Department of Biology, University of Regina, Regina, SK, Canada
| | - Kathleen A. Alexander
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA, United States
- Center for African Resources: Animals, Communities and Land Use, Kasane, Botswana
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19
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Colgan AM, Quinn HJ, Kary SC, Mitchenall LA, Maxwell A, Cameron ADS, Dorman CJ. Negative supercoiling of DNA by gyrase is inhibited in Salmonella enterica serovar Typhimurium during adaptation to acid stress. Mol Microbiol 2018; 107:734-746. [PMID: 29352745 DOI: 10.1111/mmi.13911] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 01/15/2018] [Accepted: 01/16/2018] [Indexed: 12/26/2022]
Abstract
DNA in intracellular Salmonella enterica serovar Typhimurium relaxes during growth in the acidified (pH 4-5) macrophage vacuole and DNA relaxation correlates with the upregulation of Salmonella genes involved in adaptation to the macrophage environment. Bacterial ATP levels did not increase during adaptation to acid pH unless the bacterium was deficient in MgtC, a cytoplasmic-membrane-located inhibitor of proton-driven F1 F0 ATP synthase activity. Inhibiting ATP binding by DNA gyrase and topo IV with novobiocin enhanced the effect of low pH on DNA relaxation. Bacteria expressing novobiocin-resistant (NovR ) derivatives of gyrase or topo IV also exhibited DNA relaxation at acid pH, although further relaxation with novobiocin was not seen in the strain with NovR gyrase. Thus, inhibition of the negative supercoiling activity of gyrase was the primary cause of enhanced DNA relaxation in drug-treated bacteria. The Salmonella cytosol reaches pH 5-6 in response to an external pH of 4-5: the ATP-dependent DNA supercoiling activity of purified gyrase was progressively inhibited by lowering the pH in this range, as was the ATP-dependent DNA relaxation activity of topo IV. We propose that DNA relaxation in Salmonella within macrophage is due to acid-mediated impairment of the negative supercoiling activity of gyrase.
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Affiliation(s)
- Aoife M Colgan
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Heather J Quinn
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Stefani C Kary
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.,Department of Biology, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Lesley A Mitchenall
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Anthony Maxwell
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Andrew D S Cameron
- Department of Biology, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Charles J Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
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20
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Cameron ADS, Dillon SC, Kröger C, Beran L, Dorman CJ. Broad-scale redistribution of mRNA abundance and transcriptional machinery in response to growth rate in Salmonella enterica serovar Typhimurium. Microb Genom 2017; 3:e000127. [PMID: 29177086 PMCID: PMC5695205 DOI: 10.1099/mgen.0.000127] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 07/12/2017] [Indexed: 11/18/2022] Open
Abstract
We have investigated the connection between the four-dimensional architecture of the bacterial nucleoid and the organism's global gene expression programme. By localizing the transcription machinery and the transcriptional outputs across the genome of the model bacterium Salmonella enterica serovar Typhimurium at different stages of the growth cycle, a surprising disconnection between gene dosage and transcriptional output was revealed. During exponential growth, gene output occurred chiefly in the Ori (origin), Ter (terminus) and NSL (non-structured left) domains, whereas the Left macrodomain remained transcriptionally quiescent at all stages of growth. The apparently high transcriptional output in Ter was correlated with an enhanced stability of the RNA expressed there during exponential growth, suggesting that longer mRNA half-lives compensate for low gene dosage. During exponential growth, RNA polymerase (RNAP) was detected everywhere, whereas in stationary phase cells, RNAP was concentrated in the Ter macrodomain. The alternative sigma factors RpoE, RpoH and RpoN were not required to drive transcription in these growth conditions, consistent with their observed binding to regions away from RNAP and regions of active transcription. Specifically, these alternative sigma factors were found in the Ter macrodomain during exponential growth, whereas they were localized at the Ori macrodomain in stationary phase.
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Affiliation(s)
- Andrew D S Cameron
- 1Institute of Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada.,2Department of Biology, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Shane C Dillon
- 3School of Biological Sciences, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland
| | - Carsten Kröger
- 4Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Laurens Beran
- 1Institute of Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Charles J Dorman
- 4Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
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Kröger C, Kary SC, Schauer K, Cameron ADS. Genetic Regulation of Virulence and Antibiotic Resistance in Acinetobacter baumannii. Genes (Basel) 2016; 8:genes8010012. [PMID: 28036056 PMCID: PMC5295007 DOI: 10.3390/genes8010012] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 12/18/2016] [Accepted: 12/20/2016] [Indexed: 01/14/2023] Open
Abstract
Multidrug resistant microorganisms are forecast to become the single biggest challenge to medical care in the 21st century. Over the last decades, members of the genus Acinetobacter have emerged as bacterial opportunistic pathogens, in particular as challenging nosocomial pathogens because of the rapid evolution of antimicrobial resistances. Although we lack fundamental biological insight into virulence mechanisms, an increasing number of researchers are working to identify virulence factors and to study antibiotic resistance. Here, we review current knowledge regarding the regulation of virulence genes and antibiotic resistance in Acinetobacter baumannii. A survey of the two-component systems AdeRS, BaeSR, GacSA and PmrAB explains how each contributes to antibiotic resistance and virulence gene expression, while BfmRS regulates cell envelope structures important for pathogen persistence. A. baumannii uses the transcription factors Fur and Zur to sense iron or zinc depletion and upregulate genes for metal scavenging as a critical survival tool in an animal host. Quorum sensing, nucleoid-associated proteins, and non-classical transcription factors such as AtfA and small regulatory RNAs are discussed in the context of virulence and antibiotic resistance.
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Affiliation(s)
- Carsten Kröger
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.
| | - Stefani C Kary
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.
| | - Kristina Schauer
- Department of Veterinary Science, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Oberschleißheim 85764, Germany.
| | - Andrew D S Cameron
- Department of Biology, University of Regina, Regina, SK S4S 042, Canada.
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Fitzgerald S, Dillon SC, Chao TC, Wiencko HL, Hokamp K, Cameron ADS, Dorman CJ. Re-engineering cellular physiology by rewiring high-level global regulatory genes. Sci Rep 2015; 5:17653. [PMID: 26631971 PMCID: PMC4668568 DOI: 10.1038/srep17653] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/30/2015] [Indexed: 01/10/2023] Open
Abstract
Knowledge of global regulatory networks has been exploited to rewire the gene control programmes of the model bacterium Salmonella enterica serovar Typhimurium. The product is an organism with competitive fitness that is superior to that of the wild type but tuneable under specific growth conditions. The paralogous hns and stpA global regulatory genes are located in distinct regions of the chromosome and control hundreds of target genes, many of which contribute to stress resistance. The locations of the hns and stpA open reading frames were exchanged reciprocally, each acquiring the transcription control signals of the other. The new strain had none of the compensatory mutations normally associated with alterations to hns expression in Salmonella; instead it displayed rescheduled expression of the stress and stationary phase sigma factor RpoS and its regulon. Thus the expression patterns of global regulators can be adjusted artificially to manipulate microbial physiology, creating a new and resilient organism.
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Affiliation(s)
- Stephen Fitzgerald
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.,Department of Biology, University of Regina, Saskatchewan, Canada
| | - Shane C Dillon
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Tzu-Chiao Chao
- Department of Biology, University of Regina, Saskatchewan, Canada
| | - Heather L Wiencko
- Department of Genetics, Smurfit Institute, Trinity College Dublin, Dublin 2, Ireland
| | - Karsten Hokamp
- Department of Genetics, Smurfit Institute, Trinity College Dublin, Dublin 2, Ireland
| | | | - Charles J Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
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Srikumar S, Kröger C, Hébrard M, Colgan A, Owen SV, Sivasankaran SK, Cameron ADS, Hokamp K, Hinton JCD. RNA-seq Brings New Insights to the Intra-Macrophage Transcriptome of Salmonella Typhimurium. PLoS Pathog 2015; 11:e1005262. [PMID: 26561851 PMCID: PMC4643027 DOI: 10.1371/journal.ppat.1005262] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 10/17/2015] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is arguably the world’s best-understood bacterial pathogen. However, crucial details about the genetic programs used by the bacterium to survive and replicate in macrophages have remained obscure because of the challenge of studying gene expression of intracellular pathogens during infection. Here, we report the use of deep sequencing (RNA-seq) to reveal the transcriptional architecture and gene activity of Salmonella during infection of murine macrophages, providing new insights into the strategies used by the pathogen to survive in a bactericidal immune cell. We characterized 3583 transcriptional start sites that are active within macrophages, and highlight 11 of these as candidates for the delivery of heterologous antigens from Salmonella vaccine strains. A majority (88%) of the 280 S. Typhimurium sRNAs were expressed inside macrophages, and SPI13 and SPI2 were the most highly expressed pathogenicity islands. We identified 31 S. Typhimurium genes that were strongly up-regulated inside macrophages but expressed at very low levels during in vitro growth. The SalComMac online resource allows the visualisation of every transcript expressed during bacterial replication within mammalian cells. This primary transcriptome of intra-macrophage S.-Typhimurium describes the transcriptional start sites and the transcripts responsible for virulence traits, and catalogues the sRNAs that may play a role in the regulation of gene expression during infection. The burden of Salmonellosis remains unacceptably high throughout the world and control measures have had limited success. Because Salmonella bacteria can be transmitted from the wider environment to animals and humans, the bacteria encounter diverse environments that include food, water, plant surfaces and the extracellular and intracellular phases of infection of eukaryotic hosts. An intricate transcriptional network has evolved to respond to a variety of environmental signals and control the “right time/ right place” expression of virulence genes. To understand how transcription is rewired during intracellular infection, we determined the primary transcriptome of Salmonella enterica serovar Typhimurium within murine macrophages. We report the coding genes, sRNAs and transcriptional start sites that are expressed within macrophages at 8 hours after infection, and use these to infer gene function. We identified gene promoters that are specifically expressed within macrophages and could drive the intracellular delivery of antigens by S. Typhimurium vaccine strains. These data contribute to our understanding of the mechanisms used by Salmonella to regulate virulence gene expression whilst replicating inside mammalian cells.
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Affiliation(s)
- Shabarinath Srikumar
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Carsten Kröger
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Magali Hébrard
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Aoife Colgan
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Siân V. Owen
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Sathesh K. Sivasankaran
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | | | - Karsten Hokamp
- Department of Genetics, School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College, Dublin, Ireland
| | - Jay C. D. Hinton
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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Robinson LJ, Cameron ADS, Stavrinides J. Spontaneous and on point: Do spontaneous mutations used for laboratory experiments cause pleiotropic effects that might confound bacterial infection and evolution assays? FEMS Microbiol Lett 2015; 362:fnv177. [DOI: 10.1093/femsle/fnv177] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2015] [Indexed: 01/26/2023] Open
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Quinn HJ, Cameron ADS, Dorman CJ. Bacterial regulon evolution: distinct responses and roles for the identical OmpR proteins of Salmonella Typhimurium and Escherichia coli in the acid stress response. PLoS Genet 2014; 10:e1004215. [PMID: 24603618 PMCID: PMC3945435 DOI: 10.1371/journal.pgen.1004215] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 01/16/2014] [Indexed: 12/26/2022] Open
Abstract
The evolution of new gene networks is a primary source of genetic innovation that allows bacteria to explore and exploit new niches, including pathogenic interactions with host organisms. For example, the archetypal DNA binding protein, OmpR, is identical between Salmonella Typhimurium serovar Typhimurium and Escherichia coli, but regulatory specialization has resulted in different environmental triggers of OmpR expression and largely divergent OmpR regulons. Specifically, ompR mRNA and OmpR protein levels are elevated by acid pH in S. Typhimurium but not in E. coli. This differential expression pattern is due to differences in the promoter regions of the ompR genes and the E. coli ompR orthologue can be made acid-inducible by introduction of the appropriate sequences from S. Typhimurium. The OmpR regulon in S. Typhimurium overlaps that of E. coli at only 15 genes and includes many horizontally acquired genes (including virulence genes) that E. coli does not have. We found that OmpR binds to its genomic targets in higher abundance when the DNA is relaxed, something that occurs in S. Typhimurium as a result of acid stress and which is a requirement for optimal expression of its virulence genes. The genomic targets of OmpR do not share a strong nucleotide sequence consensus: we propose that the ability of OmpR to recruit additional genes to its regulon arises from its modest requirements for specificity in its DNA targets with its preference for relaxed DNA allowing it to cooperate with DNA-topology-based allostery to modulate transcription in response to acid stress.
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Affiliation(s)
- Heather J. Quinn
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Andrew D. S. Cameron
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
- Department of Biology, University of Regina, Regina, Saskatchewan, Canada
| | - Charles J. Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
- * E-mail:
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Cameron ADS, Kröger C, Quinn HJ, Scally IK, Daly AJ, Kary SC, Dorman CJ. Transmission of an oxygen availability signal at the Salmonella enterica serovar Typhimurium fis promoter. PLoS One 2013; 8:e84382. [PMID: 24358360 PMCID: PMC3865300 DOI: 10.1371/journal.pone.0084382] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 11/14/2013] [Indexed: 11/19/2022] Open
Abstract
The nucleoid-associated protein FIS is a global regulator of gene expression and chromosome structure in Escherichia coli and Salmonella enterica. Despite the importance of FIS for infection and intracellular invasion, very little is known about the regulation of S. enterica fis expression. Under standard laboratory growth conditions, fis is highly expressed during rapid growth but is then silenced as growth slows. However, if cells are cultured in non-aerated conditions, fis expression is sustained during stationary phase. This led us to test whether the redox-sensing transcription factors ArcA and FNR regulate S. enterica fis. Deletion of FNR had no detectable effect, whereas deletion of ArcA had the unexpected effect of further elevating fis expression in stationary phase. ArcA required RpoS for induction of fis expression, suggesting that ArcA indirectly affects fis expression. Other putative regulators were found to play diverse roles: FIS acted directly as an auto-repressor (as expected), whereas CRP had little direct effect on fis expression. Deleting regions of the fis promoter led to the discovery of a novel anaerobically-induced transcription start site (Pfis-2) upstream of the primary transcription start site (Pfis-1). Promoter truncation also revealed that the shortest functional fis promoter was incapable of sustained expression. Moreover, fis expression was observed to correlate directly with DNA supercoiling in non-aerated conditions. Thus, the full-length S. enterica fis promoter region may act as a topological switch that is sensitive to stress-induced duplex destabilisation and up-regulates expression in non-aerated conditions.
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Affiliation(s)
- Andrew D. S. Cameron
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
- Department of Biology, University of Regina, Regina, SK, Canada
| | - Carsten Kröger
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Heather J. Quinn
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Isobel K. Scally
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Anne J. Daly
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Stefani C. Kary
- Department of Biology, University of Regina, Regina, SK, Canada
| | - Charles J. Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
- * E-mail:
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Kröger C, Dillon SC, Cameron ADS, Papenfort K, Sivasankaran SK, Hokamp K, Chao Y, Sittka A, Hébrard M, Händler K, Colgan A, Leekitcharoenphon P, Langridge GC, Lohan AJ, Loftus B, Lucchini S, Ussery DW, Dorman CJ, Thomson NR, Vogel J, Hinton JCD. The transcriptional landscape and small RNAs of Salmonella enterica serovar Typhimurium. Proc Natl Acad Sci U S A 2012; 109:E1277-86. [PMID: 22538806 PMCID: PMC3356629 DOI: 10.1073/pnas.1201061109] [Citation(s) in RCA: 301] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
More than 50 y of research have provided great insight into the physiology, metabolism, and molecular biology of Salmonella enterica serovar Typhimurium (S. Typhimurium), but important gaps in our knowledge remain. It is clear that a precise choreography of gene expression is required for Salmonella infection, but basic genetic information such as the global locations of transcription start sites (TSSs) has been lacking. We combined three RNA-sequencing techniques and two sequencing platforms to generate a robust picture of transcription in S. Typhimurium. Differential RNA sequencing identified 1,873 TSSs on the chromosome of S. Typhimurium SL1344 and 13% of these TSSs initiated antisense transcripts. Unique findings include the TSSs of the virulence regulators phoP, slyA, and invF. Chromatin immunoprecipitation revealed that RNA polymerase was bound to 70% of the TSSs, and two-thirds of these TSSs were associated with σ(70) (including phoP, slyA, and invF) from which we identified the -10 and -35 motifs of σ(70)-dependent S. Typhimurium gene promoters. Overall, we corrected the location of important genes and discovered 18 times more promoters than identified previously. S. Typhimurium expresses 140 small regulatory RNAs (sRNAs) at early stationary phase, including 60 newly identified sRNAs. Almost half of the experimentally verified sRNAs were found to be unique to the Salmonella genus, and <20% were found throughout the Enterobacteriaceae. This description of the transcriptional map of SL1344 advances our understanding of S. Typhimurium, arguably the most important bacterial infection model.
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Affiliation(s)
- Carsten Kröger
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Shane C. Dillon
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Andrew D. S. Cameron
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Kai Papenfort
- Institute for Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Sathesh K. Sivasankaran
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Karsten Hokamp
- Department of Genetics, School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland
| | - Yanjie Chao
- Institute for Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Alexandra Sittka
- Molecular Pulmonology, Universities of Giessen and Marburg Lung Center, German Center for Lung Research, Philipps University, 35043 Marburg, Germany
| | - Magali Hébrard
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Kristian Händler
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Aoife Colgan
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Pimlapas Leekitcharoenphon
- Department of Systems Biology, Center for Biological Sequence Analysis, and
- National Food Institute, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
| | - Gemma C. Langridge
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Amanda J. Lohan
- School of Medicine and Medical Science, Conway Institute, University College Dublin, Dublin 4, Ireland; and
| | - Brendan Loftus
- School of Medicine and Medical Science, Conway Institute, University College Dublin, Dublin 4, Ireland; and
| | - Sacha Lucchini
- Institute of Food Research, Colney, Norwich NR4 7UA, United Kingdom
| | - David W. Ussery
- Department of Systems Biology, Center for Biological Sequence Analysis, and
| | - Charles J. Dorman
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
| | - Nicholas R. Thomson
- The Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Jörg Vogel
- Institute for Molecular Infection Biology, University of Würzburg, 97080 Würzburg, Germany
| | - Jay C. D. Hinton
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, and
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Cameron ADS, Stoebel DM, Dorman CJ. DNA supercoiling is differentially regulated by environmental factors and FIS in Escherichia coli and Salmonella enterica. Mol Microbiol 2011; 80:85-101. [DOI: 10.1111/j.1365-2958.2011.07560.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Dillon SC, Cameron ADS, Hokamp K, Lucchini S, Hinton JCD, Dorman CJ. Genome-wide analysis of the H-NS and Sfh regulatory networks in Salmonella Typhimurium identifies a plasmid-encoded transcription silencing mechanism. Mol Microbiol 2010; 76:1250-65. [PMID: 20444106 DOI: 10.1111/j.1365-2958.2010.07173.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conjugative IncHI1 plasmid pSfR27 from Shigella flexneri 2a strain 2457T encodes the Sfh protein, a paralogue of the global transcriptional repressor H-NS. Sfh allows pSfR27 to be transmitted to new bacterial hosts with minimal impact on host fitness, providing a 'stealth' function whose molecular mechanism has yet to be determined. The impact of the Sfh protein on the Salmonella enterica serovar Typhimurium transcriptome was assessed and binding sites for Sfh in the Salmonella Typhimurium genome were identified by chromatin immunoprecipitation. Sfh did not bind uniquely to any sites. Instead, it bound to a subset of the larger H-NS regulatory network. Analysis of Sfh binding in the absence of H-NS revealed a greatly expanded population of Sfh binding sites that included the majority of H-NS target genes. Furthermore, the presence of plasmid pSfR27 caused a decrease in H-NS interactions with the S. Typhimurium chromosome, suggesting that the A + T-rich DNA of this large plasmid acts to titrate H-NS, removing it from chromosomal locations. It is proposed that Sfh acts as a molecular backup for H-NS and that it provides its 'stealth' function by replacing H-NS on the chromosome, thus minimizing disturbances to the H-NS-DNA binding pattern in cells that acquire pSfR27.
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Affiliation(s)
- Shane C Dillon
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
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Abstract
Escherichia coli's cAMP receptor protein (CRP), the archetypal bacterial transcription factor, regulates over a hundred promoters by binding 22 bp symmetrical sites with the consensus core half-site TGTGA. However, Haemophilus influenzae has two types of CRP sites, one like E.coli's and one with the core sequence TGCGA that regulates genes required for DNA uptake (natural competence). Only the latter 'CRP-S' sites require both CRP and the coregulator Sxy for activation. To our knowledge, the TGTGA and TGCGA motifs are the first example of one transcription factor having two distinct binding-site motifs. Here we show that CRP-S promoters are widespread in the gamma-proteobacteria and demonstrate their Sxy-dependence in E.coli. Orthologs of most H.influenzae CRP-S-regulated genes are ubiquitous in the five best-studied gamma-proteobacteria families, Enterobacteriaceae, Pasteurellaceae, Pseudomonadaceae, Vibrionaceae and Xanthomonadaceae. Phylogenetic footprinting identified CRP-S sites in the promoter regions of the Enterobacteriaceae, Pasteurellaceae and Vibrionaceae orthologs, and canonical CRP sites in orthologs of genes known to be Sxy-independent in H.influenzae. Bandshift experiments confirmed that E.coli CRP-S sequences are low affinity binding sites for CRP, and mRNA analysis showed that they require CRP, cAMP (CRP's allosteric effector) and Sxy for gene induction. This work suggests not only that the gamma-proteobacteria share a common DNA uptake mechanism, but also that, in the three best studied families, their competence regulons share both CRP-S specificity and Sxy dependence.
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Affiliation(s)
- Andrew D. S. Cameron
- Department of Microbiology and Immunology, University of British ColumbiaVancouver, BC, Canada
| | - Rosemary J. Redfield
- Department of Zoology, University of British ColumbiaVancouver, BC, Canada
- To whom correspondence should be addressed at Life Sciences Centre (Zoology), 2350 Health Sciences Mall, University of British Columbia, Vancouver, BC, Canada V6T 1Z3. Tel: +604 822 3744; Fax: +604 827 4135;
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Redfield RJ, Cameron ADS, Qian Q, Hinds J, Ali TR, Kroll JS, Langford PR. A novel CRP-dependent regulon controls expression of competence genes in Haemophilus influenzae. J Mol Biol 2005; 347:735-47. [PMID: 15769466 DOI: 10.1016/j.jmb.2005.01.012] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2004] [Revised: 12/23/2004] [Accepted: 01/05/2005] [Indexed: 01/19/2023]
Abstract
Natural competence for DNA uptake is common among bacteria but its evolutionary function is controversial. Resolving the dispute requires a detailed understanding of both how cells decide to take up DNA and how the DNA is processed during and after uptake. We have used whole-genome microarrays to follow changes in gene expression during competence development in wild-type Haemophilus influenzae cells, and to characterize dependence of competence-induced transcription on known regulatory factors. This analysis confirmed the existence of a postulated competence regulon, characterized by a promoter-associated 22 bp competence regulatory element (CRE) closely related to the cAMP receptor protein (CRP) binding consensus. This CRE regulon contains 25 genes in 13 transcription units, only about half of which have been previously associated with competence. The new CRE genes encode a periplasmic ATP-dependent DNA ligase, homologs of SSB, RadC and the Bacillus subtilis DNA uptake protein ComEA, and eight genes of unknown function. Competence-induced transcription of genes in the CRE regulon is strongly dependent on cAMP, consistent with the known role of catabolite regulation in competence. Electrophoretic mobility-shift assays confirmed that CRE sequences are a new class of CRP-binding site. The essential competence gene sxy is induced early in competence development and is required for competence-induced transcription of CRE-regulon genes but not other CRP-regulated genes, suggesting that Sxy may act as an accessory factor directing CRP to CRE sites. Natural selection has united these 25 genes under a common regulatory mechanism. Elucidating this mechanism, and the functions of the genes, will provide a valuable window into the evolutionary function of natural competence.
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Affiliation(s)
- Rosemary J Redfield
- Department of Zoology, University of British Columbia, Vancouver, Canada V6T 1Z4.
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