Phase variation of<i>Clostridium difficile</i>virulence factors

Anjuwon-Foster, Brandon R.; Tamayo, Rita

doi:10.1080/19490976.2017.1362526

Cited by 46 publications

(44 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Phase variation is defined as rapid and reversible ON/OFF changes in gene expression (60). It occurs by several different molecular mechanisms and contributes to virulence in multiple pathogens including E. coli , Neisseria meningiditis , Mycoplasma agalactiae, Listeria monocytogenes , and Clostridium difficile (61–66), It is an advantageous form of gene regulation for pathogens as it helps a population cope with sudden changes in environmental conditions during infection (67). The presence of a subset of the population in alternative phase states circumvents the need for transcriptional and translational activation steps in response to changing conditions.…”

Section: Discussionmentioning

confidence: 99%

Identification and characterization of a phase-variable element that regulates the autotransporter UpaE in uropathogenicEscherichia coli

Welch

Goh

Atruksang

et al. 2018

Preprint

View full text Add to dashboard Cite

word count: 249 7 8 Main text word count: 4,284 9 10 11 12 1. Abstract 24Uropathogenic Escherichia coli (UPEC) are the most common etiological agent 25 of uncomplicated urinary tract infection (UTI). An important mechanism of gene 26 regulation in UPEC is phase variation that involves inversion of a promoter-containing 27 DNA element via enzymatic activity of tyrosine recombinases, resulting in biphasic, ON 28 or OFF expression of target genes. The UPEC reference strain CFT073 has five 29 tyrosine site-specific recombinases that function at two previously characterized 30 promoter inversion systems, fimS and hyxS. Three of the five recombinases are located 31 proximally to their cognate target elements, which is typical of promoter inversion 32 systems. The genes for the other two recombinases, IpuA and IpuB are located distal 33 from these sites. Here, we identified and characterized a third phase variable invertible 34 element in CFT073, ipuS located proximal to ipuA and ipuB. The inversion of ipuS is 35 catalyzed by four of the five CFT073 recombinases. Orientation of the element drives 36 transcription of a two-gene operon containing ipuR, a predicted LuxR-type regulator, 37 and upaE, a predicted autotransporter. We show that the predicted autotransporter 38UpaE is surface-located and facilitates biofilm formation as well as adhesion to 39 extracellular matrix proteins in a K-12 recombinant background. Consistent with this 40 phenotype, the ipuS ON condition in CFT073 results in defective swimming motility, 41 increased adherence to human kidney epithelial cells, and a positive competitive kidney 42 colonization advantage in experimental mouse UTI infections. Overall, the identification 43 of a third phase-switch in UPEC that is regulated by a shared set of recombinases 44 describes a complex phase-variable virulence network in UPEC. 45 46 Importance 47 Uropathogenic Escherichia coli (UPEC) is the most common cause of urinary 48 tract infection (UTI). ON versus OFF phase-switching by inversion of small DNA 49 elements at two chromosome sites in UPEC regulates the expression of important 50 virulence factors, including the type 1 fimbriae adhesion organelle. In this report, we 51 describe a third invertible element, ipuS, in the UPEC reference strain CFT073. The 52 inversion of ipuS controls the phase variable expression of upaE, an autotransporter 53 gene that encodes a surface protein involved in adherence to extracellular matrix 54 proteins and colonization of the kidneys in a murine model of UTI. 55 56 Introduction 57 Urinary tract infections (UTIs) are one of the most common infections diagnosed 58 in clinics and hospitals. Nearly 50% of women will experience a UTI in their lifetime with 59 treatment costs exceeding $3.5 billion annually in the United States (1, 2). The most 60 common etiological agent of uncomplicated UTIs are uropathogenic Escherichia coli 61 (UPEC), which account for ~80% of reported infections (3). The predicted reservoir of 62 UPEC is the colon and infection follows an ascending rout...

show abstract

Section: Discussionmentioning

confidence: 99%

Identification and characterization of a phase-variable element that regulates the autotransporter UpaE in uropathogenicEscherichia coli

Welch

Goh

Atruksang

et al. 2018

Preprint

View full text Add to dashboard Cite

show abstract

“…The C. difficile strain R20291, a ribotype 027 strain associated with epidemic infections, exhibits two distinct colony morphologies: a “smooth” colony that is round and circular, and a “rough” colony that is flatter and has filamentous edges (18–20). In addition to R20291, strains UK1 (ribotype 027), VPI10463 (ribotype 087), 630 (ribotype 012), and ATCC 43598 (ribotype 017) yielded both rough and smooth colonies (Figure 1).…”

Section: Resultsmentioning

confidence: 99%

“…A few transcriptional regulators have been reported to phase vary, including the global virulence gene regulators BvgAS in Bordetella and the response regulator FlgR in Campylobacter jejuni (57–59). In C. difficile , phase variation of flagellar genes impacts the transcription of the alternative sigma factor gene sigD , which couples the expression of flagellum and toxin genes, linking virulence factor production to the orientation of the flagellar switch (19, 60). Coordinated regulation of genes resulting in global changes in transcription can also result from phase variation of DNA modification systems, as observed in Haemophilus influenza , Helicobacter pylori , Salmonella enterica , and Streptococcus strains.…”

Section: Discussionmentioning

confidence: 99%

“…Many aspects of C. difficile physiology and pathogenesis remain poorly understood. For example, some Clostridioides species, including C. difficile , are capable of forming two distinct colony morphologies; one is smooth and circular, and the other is rough and filamentous (17–20). However, the underlying mechanisms and physiological relevance of this dimorphism are unknown.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Phase variation of a signal transduction system controlsClostridioides difficilecolony morphology, motility, and virulence

Garrett

Sekulović

Wetzel

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

23di-GMP, biofilm 2 24 Abstract 25Recent work has revealed that Clostridioides difficile, a major cause of nosocomial diarrheal 26 disease, exhibits phenotypic heterogeneity within a clonal population as a result of phase 27 variation. Many C. difficile strains representing multiple ribotypes develop two colony 28 morphotypes, termed rough and smooth, but the biological implications of this phenomenon 29 have not been explored. Here, we examine the molecular basis and physiological relevance 30 of the distinct colony morphotypes produced by this bacterium. We show that C. difficile 31 reversibly differentiates into rough and smooth colony morphologies, and that bacteria 32 derived from the isolates display opposing surface and swimming motility behaviors. We 33identified an atypical phase-variable signal transduction system consisting of a histidine 34 kinase and two response regulators, named herein CmrRST, which mediates the switch in 35 colony morphology and motility behaviors. The CmrRST-regulated surface motility is 36 independent of Type IV pili, suggesting a novel mechanism of surface expansion in C. 37difficile. Microscopic analysis of cell and colony structure indicates that CmrRST promotes 38 the formation of elongated bacteria arranged in bundled chains, which may contribute to 39 bacterial migration. In a hamster model of acute C. difficile disease, colony morphology 40 correlates with virulence, and the CmrRST system is required for disease development. 41Furthermore, we provide evidence that CmrRST phase varies during infection, suggesting 42 that the intestinal environment impacts the proportion of CmrRST-expressing C. difficile. 43Our findings indicate that C. difficile employs phase variation of the CmrRST signal 44 transduction system to generate phenotypic heterogeneity during infection, with 45 concomitant effects on bacterial physiology and pathogenesis. 46 3 47 Significance Statement 48 Phenotypic heterogeneity within a genetically clonal population allows many mucosal 49 pathogens to survive within their hosts, balancing the need to produce factors that 50 promote colonization and persistence with the need to avoid the recognition of those 51 factors by the host immune system. Recent work suggests that the human intestinal 52 pathogen Clostridium difficile employs phase variation during infection to generate a 53 heterogeneous population differing in swimming motility, toxin production, and more. 54 This study identifies a signal transduction system that broadly impacts C. difficile 55 physiology and behavior in vitro and in an animal model. Phase variation of this system 56 is therefore poised to modulate the coordinated expression of multiple mechanisms 57 influencing C. difficile disease development. 4 58 59Phenotypic heterogeneity within bacterial populations is a widely established 60 phenomenon that allows the population to survive sudden environmental changes (1-3). 61Heterogeneity serves as a "bet-hedging" strategy such that a subpopulation can persist 62 and propagate an advantageo...

show abstract

“…RecV, a site-specific tyrosine recombinase, mediates inversion of the flagellar switch (13). The phase variable production of flagella and toxins was proposed to allow C. difficile to balance the benefits of swimming motility and toxinogenesis with the cost of producing these immunogenic factors (14-17).…”

Section: Introductionmentioning

confidence: 99%

Characterization of flagellar and toxin phase variation inClostridium difficileribotype 012 isolates

Anjuwon-Foster

Maldonado-Vazquez

Tamayo

2018

Preprint

Self Cite

View full text Add to dashboard Cite

20Clostridium difficile causes diarrheal diseases mediated in part by the secreted 21 toxins TcdA and TcdB. C. difficile produces flagella that also contribute to motility and 22 bacterial adherence to intestinal cells during infection. Flagellum and toxin gene 23 expression are linked via the flagellar alternative sigma factor, SigD. Recently, we 24 identified a "flagellar switch" upstream of the early flagellar biosynthesis operon that 25 mediates phase variation of both flagellum and toxin production in C. difficile strain 26 R20291. However, we were unable to detect flagellar switch inversion in C. difficile 27 strain 630, a ribotype 012 strain commonly used in research labs, suggesting the strain 28 is phase-locked. To determine whether a "phase locked" flagellar switch is limited to 630 29 or present more broadly in ribotype 012 strains, we assessed the frequency and 30 phenotypic outcomes of flagellar switch inversion in multiple C. difficile ribotype 012 31isolates. The laboratory-adapted strain JIR8094, a derivative of strain 630, and six 32 clinical and environmental isolates were all found to be phase OFF, non-motile, and 33 attenuated for toxin production. We isolated low frequency motile derivatives of JIR8094 34 with partial recovery of motility and toxin production, and found that additional changes 35 in JIR8094 impact these processes. The clinical and environmental isolates varied 36 considerably in the frequency by which flagellar phase ON derivatives arose, and these 37 derivatives showed fully restored motility and toxin production. Taken together, these 38 results demonstrate heterogeneity in flagellar and toxin phase variation among C.

show abstract

Phase variation ofClostridium difficilevirulence factors

Cited by 46 publications

References 50 publications

Identification and characterization of a phase-variable element that regulates the autotransporter UpaE in uropathogenicEscherichia coli

Identification and characterization of a phase-variable element that regulates the autotransporter UpaE in uropathogenicEscherichia coli

Phase variation of a signal transduction system controlsClostridioides difficilecolony morphology, motility, and virulence

Characterization of flagellar and toxin phase variation inClostridium difficileribotype 012 isolates

Contact Info

Product

Resources

About