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Holmes J, Munjoma L, Bayliss CD. Novel method for prediction of combinatorial phase-variable gene expression states. MethodsX 2023; 11:102392. [PMID: 37817978 PMCID: PMC10561117 DOI: 10.1016/j.mex.2023.102392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 09/21/2023] [Indexed: 10/12/2023] Open
Abstract
Short sequence repeat mediated phase variation results in diverse phenotype presentation in many bacteria including Campylobacter and Neisseria species. Current methods for identifying the expression states of phase-variable genes involve taking a high number of single colonies. This approach is subject to bias, sampling effects and high workloads that reduce the ability to perform intermediary sampling. The use of high concentration colony sweeps provides a work around but reduces the resolution of combinatorial expression profiles (termed phasotypes). A parsimonious approach combining both single colony and sweep data was developed to overcome these limitations. The critical methodological advance is the use of an algorithm that utilises the experimental data from the two sample types and a parsimonious, iterative mathematical analysis that outputs the phasotype distribution with the highest likelihood of underpinning the experimental data sets. The advantages of this unified method are increased resolution and accuracy of gene expression state combinations as compared to conventional single colony sampling, reduced requirement for sampling large numbers of colonies leading to reduced costs, and a higher capacity for collecting samples and replicates.•Inputting of sweep and single colony data into an algorithm for a rapid determination of the combinatorial phase variation states (phasotypes) for repeat-mediated phase-variable bacterial genes•This method reduces the number of single colony samples required to produce accurate estimates of phasotypes•This method will reduce the costs of phasotype analyses and increase potential to analyse more time points or sample sites leading to an improved understanding of how phase variation contributes to bacterial host persistence and the ability to cause disease.
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Affiliation(s)
- Jonathan Holmes
- Department of Genetics and Genome Biology, University of Leicester, United Kingdom
| | - Lickson Munjoma
- Department of Genetics and Genome Biology, University of Leicester, United Kingdom
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Nothaft H, Perez-Muñoz ME, Yang T, Murugan AVM, Miller M, Kolarich D, Plastow GS, Walter J, Szymanski CM. Improving Chicken Responses to Glycoconjugate Vaccination Against Campylobacter jejuni. Front Microbiol 2021; 12:734526. [PMID: 34867850 PMCID: PMC8637857 DOI: 10.3389/fmicb.2021.734526] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 10/04/2021] [Indexed: 01/03/2023] Open
Abstract
Campylobacter jejuni is a common cause of diarrheal disease worldwide. Human infection typically occurs through the ingestion of contaminated poultry products. We previously demonstrated that an attenuated Escherichia coli live vaccine strain expressing the C. jejuni N-glycan on its surface reduced the Campylobacter load in more than 50% of vaccinated leghorn and broiler birds to undetectable levels (responder birds), whereas the remainder of the animals was still colonized (non-responders). To understand the underlying mechanism, we conducted three vaccination and challenge studies using 135 broiler birds and found a similar responder/non-responder effect. Subsequent genome-wide association studies (GWAS), analyses of bird sex and levels of vaccine-induced IgY responses did not correlate with the responder versus non-responder phenotype. In contrast, antibodies isolated from responder birds displayed a higher Campylobacter-opsonophagocytic activity when compared to antisera from non-responder birds. No differences in the N-glycome of the sera could be detected, although minor changes in IgY glycosylation warrant further investigation. As reported before, the composition of the microbiota, particularly levels of OTU classified as Clostridium spp., Ruminococcaceae and Lachnospiraceae are associated with the response. Transplantation of the cecal microbiota of responder birds into new birds in combination with vaccination resulted in further increases in vaccine-induced antigen-specific IgY responses when compared to birds that did not receive microbiota transplants. Our work suggests that the IgY effector function and microbiota contribute to the efficacy of the E. coli live vaccine, information that could form the basis for the development of improved vaccines targeted at the elimination of C. jejuni from poultry.
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Affiliation(s)
- Harald Nothaft
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada
| | - Maria Elisa Perez-Muñoz
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Tianfu Yang
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Abarna V M Murugan
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, Australia
| | | | - Daniel Kolarich
- Institute for Glycomics, Griffith University, Gold Coast Campus, Southport, QLD, Australia.,ARC Centre of Excellence for Nanoscale BioPhotonics, Griffith University, Southport, QLD, Australia
| | - Graham S Plastow
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, AB, Canada.,Livestock Gentec, Edmonton, AB, Canada
| | - Jens Walter
- Department of Agricultural, Food & Nutritional Science, University of Alberta, Edmonton, AB, Canada
| | - Christine M Szymanski
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada.,Department of Microbiology and Complex Carbohydrate Research Center, University of Georgia, Athens, GA, United States
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Yamamoto S, Iyoda S, Ohnishi M. Stabilizing Genetically Unstable Simple Sequence Repeats in the Campylobacter jejuni Genome by Multiplex Genome Editing: a Reliable Approach for Delineating Multiple Phase-Variable Genes. mBio 2021; 12:e0140121. [PMID: 34425708 PMCID: PMC8437040 DOI: 10.1128/mbio.01401-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 07/21/2021] [Indexed: 11/20/2022] Open
Abstract
Hypermutable simple sequence repeats (SSRs) are major drivers of phase variation in Campylobacter jejuni. The presence of multiple SSR-mediated phase-variable genes encoding enzymes that modify surface structures, including capsular polysaccharide (CPS) and lipooligosaccharide (LOS), generates extreme cell surface diversity within bacterial populations, thereby promoting adaptation to selective pressures in host environments. Therefore, genetically controlling SSR-mediated phase variation can be important for achieving stable and reproducible research on C. jejuni. Here, we show that natural "cotransformation" is an effective method for C. jejuni genome editing. Cotransformation is a trait of naturally competent bacteria that causes uptake/integration of multiple different DNA molecules, which has been recently adapted to multiplex genome editing by natural transformation (MuGENT), a method for introducing multiple mutations into the genomes of these bacteria. We found that cotransformation efficiently occurred in C. jejuni. To examine the feasibility of MuGENT in C. jejuni, we "locked" different polyG SSR tracts in strain NCTC11168 (which are located in the biosynthetic CPS/LOS gene clusters) into either the ON or OFF configurations. This approach, termed "MuGENT-SSR," enabled the generation of all eight edits within 2 weeks and the identification of a phase-locked strain with a highly stable type of Penner serotyping, a CPS-based serotyping scheme. Furthermore, extensive genome editing of this strain by MuGENT-SSR identified a phase-variable gene that determines the Penner serotype of NCTC11168. Thus, MuGENT-SSR provides a platform for genetic and phenotypic engineering of genetically unstable C. jejuni, making it a reliable approach for elucidating the mechanisms underlying phase-variable expression of specific phenotypes. IMPORTANCE Campylobacter jejuni is the leading bacterial cause of foodborne gastroenteritis in developed countries and occasionally progresses to the autoimmune disease Guillain-Barré syndrome. A relatively large number of hypermutable simple sequence repeat (SSR) tracts in the C. jejuni genome markedly decreases its phenotypic stability through reversible changes in the ON or OFF expression states of the genes in which they reside, a phenomenon called phase variation. Thus, controlling SSR-mediated phase variation can be important for achieving stable and reproducible research on C. jejuni. In this study, we developed a feasible and effective approach for genetically manipulate multiple SSR tracts in the C. jejuni genome using natural cotransformation, a trait of naturally transformable bacterial species that causes the uptake and integration of multiple different DNA molecules. This approach will greatly help to improve the genetic and phenotypic stability of C. jejuni to enable diverse applications in research and development.
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Affiliation(s)
- Shouji Yamamoto
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Sunao Iyoda
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Makoto Ohnishi
- Department of Bacteriology I, National Institute of Infectious Diseases, Tokyo, Japan
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Cayrou C, Barratt NA, Ketley JM, Bayliss CD. Phase Variation During Host Colonization and Invasion by Campylobacter jejuni and Other Campylobacter Species. Front Microbiol 2021; 12:705139. [PMID: 34394054 PMCID: PMC8355987 DOI: 10.3389/fmicb.2021.705139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
Phase variation (PV) is a phenomenon common to a variety of bacterial species for niche adaption and survival in challenging environments. Among Campylobacter species, PV depends on the presence of intergenic and intragenic hypermutable G/C homopolymeric tracts. The presence of phase-variable genes is of especial interest for species that cause foodborne or zoonotic infections in humans. PV influences the formation and the structure of the lipooligosaccharide, flagella, and capsule in Campylobacter species. PV of components of these molecules is potentially important during invasion of host tissues, spread within hosts and transmission between hosts. Motility is a critical phenotype that is potentially modulated by PV. Variation in the status of the phase-variable genes has been observed to occur during colonization in chickens and mouse infection models. Interestingly, PV is also involved in bacterial survival of attack by bacteriophages even during chicken colonization. This review aims to explore and discuss observations of PV during model and natural infections by Campylobacter species and how PV may affect strategies for fighting infections by this foodborne pathogen.
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Affiliation(s)
- Caroline Cayrou
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Natalie A Barratt
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Julian M Ketley
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
| | - Christopher D Bayliss
- Department of Genetics and Genome Biology, University of Leicester, Leicester, United Kingdom
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De Ste Croix M, Holmes J, Wanford JJ, Moxon ER, Oggioni MR, Bayliss CD. Selective and non-selective bottlenecks as drivers of the evolution of hypermutable bacterial loci. Mol Microbiol 2020; 113:672-681. [PMID: 32185830 PMCID: PMC7154626 DOI: 10.1111/mmi.14453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/20/2019] [Accepted: 01/09/2020] [Indexed: 12/28/2022]
Abstract
Bottlenecks reduce the size of the gene pool within populations of all life forms with implications for their subsequent survival. Here, we examine the effects of bottlenecks on bacterial commensal-pathogens during transmission between, and dissemination within, hosts. By reducing genetic diversity, bottlenecks may alter individual or population-wide adaptive potential. A diverse range of hypermutable mechanisms have evolved in infectious agents that allow for rapid generation of genetic diversity in specific genomic loci as opposed to the variability arising from increased genome-wide mutation rates. These localised hypermutable mechanisms include multi-gene phase variation (PV) of outer membrane components, multi-allele PV of restriction systems and recombination-driven antigenic variation. We review selected experimental and theoretical (mathematical) models pertaining to the hypothesis that localised hypermutation (LH) compensates for fitness losses caused by bottlenecks and discuss whether bottlenecks have driven the evolution of hypermutable loci.
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Affiliation(s)
- Megan De Ste Croix
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Jonathan Holmes
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Joseph J Wanford
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - E Richard Moxon
- Department of Paediatrics, University of Oxford Medical Sciences Division, John Radcliffe Hospital, Oxford, UK
| | - Marco R Oggioni
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
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Trzilova D, Tamayo R. Site-Specific Recombination - How Simple DNA Inversions Produce Complex Phenotypic Heterogeneity in Bacterial Populations. Trends Genet 2020; 37:59-72. [PMID: 33008627 DOI: 10.1016/j.tig.2020.09.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/26/2020] [Accepted: 09/01/2020] [Indexed: 02/07/2023]
Abstract
Many bacterial species generate phenotypically heterogeneous subpopulations as a strategy for ensuring the survival of the population as a whole - an environmental stress that eradicates one subpopulation may leave other phenotypic groups unharmed, allowing the lineage to continue. Phase variation, a process that functions as an ON/OFF switch for gene expression, is one way that bacteria achieve phenotypic heterogeneity. Phase variation occurs stochastically and reversibly, and in the presence of a selective pressure the advantageous phenotype(s) predominates in the population. Phase variation can occur through multiple genetic and epigenetic mechanisms. This review focuses on conservative site-specific recombination that generates reversible DNA inversions as a genetic mechanism mediating phase variation. Recent studies have sparked a renewed interest in phase variation mediated through DNA inversion, revealing a high level of complexity beyond simple ON/OFF switching, including unusual modes of gene regulation, and highlighting an underappreciation of the use of these mechanisms by bacteria.
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Affiliation(s)
- Dominika Trzilova
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA
| | - Rita Tamayo
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, NC, USA.
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Hameed A, Woodacre A, Machado LR, Marsden GL. An Updated Classification System and Review of the Lipooligosaccharide Biosynthesis Gene Locus in Campylobacter jejuni. Front Microbiol 2020; 11:677. [PMID: 32508756 PMCID: PMC7248181 DOI: 10.3389/fmicb.2020.00677] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 03/24/2020] [Indexed: 01/21/2023] Open
Abstract
Lipooligosaccharide (LOS) is an integral component of the Campylobacter cell membrane with a structure of core oligosaccharides forming inner and outer core regions and a lipid A moiety. The gene content of the LOS core biosynthesis cluster exhibits extensive sequence variation, which leads to the production of variable cell surface LOS structures in Campylobacter. Some LOS outer core molecules in Campylobacter jejuni are molecular mimics of host structures (such as neuronal gangliosides) and are thought to trigger neuronal disorders (particularly Guillain–Barré syndrome and Miller Fisher syndrome) in humans. The extensive genetic variation in the LOS biosynthesis gene cluster, a majority of which occurs in the LOS outer core biosynthesis gene content present between lgtF and waaV, has led to the development of a classification system with 23 classes (A–W) and four groups (1–4) for the C. jejuni LOS region. This review presents an updated and simplified classification system for LOS typing alongside an overview of the frequency of C. jejuni LOS biosynthesis genotypes and structures in various C. jejuni populations.
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Affiliation(s)
- Amber Hameed
- Division of Life Sciences, University of Northampton, Northampton, United Kingdom
| | - Alexandra Woodacre
- Division of Life Sciences, University of Northampton, Northampton, United Kingdom
| | - Lee R Machado
- Division of Life Sciences, University of Northampton, Northampton, United Kingdom
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Bayliss CD, Fallaize C, Howitt R, Tretyakov MV. Mutation and Selection in Bacteria: Modelling and Calibration. Bull Math Biol 2018; 81:639-675. [PMID: 30430330 PMCID: PMC6373360 DOI: 10.1007/s11538-018-0529-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 10/26/2018] [Indexed: 11/28/2022]
Abstract
Temporal evolution of a clonal bacterial population is modelled taking into account reversible mutation and selection mechanisms. For the mutation model, an efficient algorithm is proposed to verify whether experimental data can be explained by this model. The selection–mutation model has unobservable fitness parameters, and, to estimate them, we use an Approximate Bayesian Computation algorithm. The algorithms are illustrated using in vitro data for phase variable genes of Campylobacter jejuni.
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Affiliation(s)
- C D Bayliss
- Department of Genetics, University of Leicester, Leicester, LE1 7RH, UK
| | - C Fallaize
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - R Howitt
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - M V Tretyakov
- School of Mathematical Sciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
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Aidley J, Wanford JJ, Green LR, Sheppard SK, Bayliss CD. PhasomeIt: an 'omics' approach to cataloguing the potential breadth of phase variation in the genus Campylobacter. Microb Genom 2018; 4:e000228. [PMID: 30351264 PMCID: PMC6321876 DOI: 10.1099/mgen.0.000228] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 09/13/2018] [Indexed: 11/18/2022] Open
Abstract
Hypermutable simple sequence repeats (SSRs) are drivers of phase variation (PV) whose stochastic, high-frequency, reversible switches in gene expression are a common feature of several pathogenic bacterial species, including the human pathogen Campylobacter jejuni. Here we examine the distribution and conservation of known and putative SSR-driven phase variable genes - the phasome - in the genus Campylobacter. PhasomeIt, a new program, was specifically designed for rapid identification of SSR-mediated PV. This program detects the location, type and repeat number of every SSR. Each SSR is linked to a specific gene and its putative expression state. Other outputs include conservation of SSR-driven phase-variable genes and the 'core phasome' - the minimal set of PV genes in a phylogenetic grouping. Analysis of 77 complete Campylobacter genome sequences detected a 'core phasome' of conserved PV genes in each species and a large number of rare PV genes with few, or no, homologues in other genome sequences. Analysis of a set of partial genome sequences, with food-chain-associated metadata, detected evidence of a weak link between phasome and source host for disease-causing isolates of sequence type (ST)-828 but not the ST-21 or ST-45 complexes. Investigation of the phasomes in the genus Campylobacter provided evidence of overlapping but distinctive mechanisms of PV-mediated adaptation to specific niches. This suggests that the phasome could be involved in host adaptation and spread of campylobacters. Finally, this tool is malleable and will have utility for studying the distribution and genic effects of other repetitive elements in diverse bacterial species.
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Affiliation(s)
- Jack Aidley
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Joseph J. Wanford
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Luke R. Green
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Samuel K. Sheppard
- Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK
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