The Repeat-In-Toxin Family Member TosA Mediates Adherence of Uropathogenic Escherichia coli and Survival during Bacteremia

Vigil, Patrick D.; Wiles, Travis J.; Engstrom, Michael D.; Prasov, Lev; Mulvey, Matthew; Mobley, Harry L. T.

doi:10.1128/iai.05713-11

Cited by 50 publications

(63 citation statements)

References 42 publications

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“…Previous work identified and characterized the E. coli repeatsin-toxin (RTX) nonfimbrial adhesin TosA (i.e., type one secretion as the predicted secretion mechanism) (7,(9)(10)(11)(12)(13). In particular, it was noted that tosA and the other tos operon genes have poor in vitro expression (9)(10)(11).…”

mentioning

confidence: 99%

Regulation of Expression of Uropathogenic Escherichia coli Nonfimbrial Adhesin TosA by PapB Homolog TosR in Conjunction with H-NS and Lrp

Engstrom

Mobley

2016

Infect Immun

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Urinary tract infections (UTIs) are a major burden to human health. The overwhelming majority of UTIs are caused by uropathogenic Escherichia coli (UPEC) strains. Unlike some pathogens, UPEC strains do not have a fixed core set of virulence and fitness factors but do have a variety of adhesins and regulatory pathways. One such UPEC adhesin is the nonfimbrial adhesin TosA, which mediates adherence to the epithelium of the upper urinary tract. The tos operon is AT rich, resides on pathogenicity island aspV, and is not expressed under laboratory conditions. Because of this, we hypothesized that tosA expression is silenced by H-NS. Lrp, based on its prominent function in the regulation of other adhesins, is also hypothesized to contribute to tos operon regulation. Using a variety of in vitro techniques, we mapped both the tos operon promoter and TosR binding sites. We have now identified TosR as a dual regulator of the tos operon, which could control the tos operon in association with H-NS and Lrp. H-NS is a negative regulator of the tos operon, and Lrp positively regulates the tos operon. Exogenous leucine also inhibits Lrp-mediated tos operon positive regulation. In addition, TosR binds to the pap operon, which encodes another important UPEC adhesin, P fimbria. Induction of TosR synthesis reduces production of P fimbria. These studies advance our knowledge of regulation of adhesin expression associated with uropathogen colonization of a host. U rinary tract infections (UTIs), which are among the most common bacterial infections of humans (1), can occur in otherwise healthy individuals when bacteria colonizing the gastrointestinal tract gain access to the periurethral area. Most individuals with UTIs develop an infection of the bladder, referred to as cystitis (1). However, the infecting bacterium may ascend the ureters to infect the kidneys (pyelonephritis) and, in some cases, enter the bloodstream leading to bacteremia and sometimes fatal urosepsis (1-4).A diverse group of extraintestinal pathogenic Escherichia coli strains, referred to as uropathogenic E. coli (UPEC), cause the overwhelming majority of uncomplicated UTIs (2, 5). While numerous UPEC virulence factors have been identified, including adhesins, motility systems, toxins, and iron acquisition systems, a core set of virulence factors has not been strictly defined (6-8). However, it is critical to understand specific virulence factors and how they are regulated.Previous work identified and characterized the E. coli repeatsin-toxin (RTX) nonfimbrial adhesin TosA (i.e., type one secretion as the predicted secretion mechanism) (7, 9-13). In particular, it was noted that tosA and the other tos operon genes have poor in vitro expression (9-11). TosA, a Ͼ250-kDa surface-exposed protein, mediates UPEC adherence to epithelial cells derived from the upper urinary tract (9). This is in contrast to a number of other RTX proteins, which are fully secreted into the extracellular milieu and act as toxins (14-18). We estimated that ϳ32% of UPEC strains carry genes enc...

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confidence: 99%

Regulation of Expression of Uropathogenic Escherichia coli Nonfimbrial Adhesin TosA by PapB Homolog TosR in Conjunction with H-NS and Lrp

Engstrom

Mobley

2016

Infect Immun

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“…Within a single day, hundreds of fish can be injected, with minimal costs, taking up only a rack or two within an incubator. Zebrafish embryos are also transparent, allowing easy, real-time observation of the infection process, including visualization of fluorescent gene expression reporters as well as fluorescently tagged bacteria, proteins, and host cell lineages (207,231). Heart rate and blood flow are also easily monitored in the transparent embryos, along with bacterial dissemination and the development of necrotic lesions or other anomalies in host tissues.…”

Section: Zebrafishmentioning

confidence: 99%

“…In addition, zebrafish are typically maintained at 28.5°C, notably lower than the temperature in most mammalian hosts. Nonetheless, zebrafish have proven to be remarkably useful for delineating UPEC-associated fitness and virulence factors that are relevant to the infection process in mammals (203,204,207,231,243). The discovery and functional analysis of both bacterial and host factors of importance to UPEC pathogenesis will likely advance in strides as imaging and genetic approaches in the zebrafish model continue to be developed and improved.…”

Section: Zebrafishmentioning

confidence: 99%

“…Rodents, and mice in particular, have also been used to model systemic infections, mimicking episodes of bacteremia and urosepsis that can arise in human patients as serious complications of UTI (203)(204)(205)(206)(207)(208). In these models, UPEC is inoculated directly into the bloodstream or delivered systemically via a subcutaneous or intraperitoneal injection.…”

Section: Murinementioning

confidence: 99%

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Strengths and Limitations of Model Systems for the Study of Urinary Tract Infections and Related Pathologies

Barber

Norton

Wiles

et al. 2016

Microbiol Mol Biol Rev

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SUMMARYUrinary tract infections (UTIs) are some of the most common bacterial infections worldwide and are a source of substantial morbidity among otherwise healthy women. UTIs can be caused by a variety of microbes, but the predominant etiologic agent of these infections is uropathogenicEscherichia coli(UPEC). An especially troubling feature of UPEC-associated UTIs is their high rate of recurrence. This problem is compounded by the drastic increase in the global incidence of antibiotic-resistant UPEC strains over the past 15 years. The need for more-effective treatments for UTIs is driving research aimed at bettering our understanding of the virulence mechanisms and host-pathogen interactions that occur during the course of these infections. Surrogate models of human infection, including cell culture systems and the use of murine, porcine, avian, teleost (zebrafish), and nematode hosts, are being employed to define host and bacterial factors that modulate the pathogenesis of UTIs. These model systems are revealing how UPEC strains can avoid or overcome host defenses and acquire scarce nutrients while also providing insight into the virulence mechanisms used by UPEC within compromised individuals, such as catheterized patients. Here, we summarize our current understanding of UTI pathogenesis while also giving an overview of the model systems used to study the initiation, persistence, and recurrence of UTIs and life-threatening sequelae like urosepsis. Although we focus on UPEC, the experimental systems described here can also provide valuable insight into the disease processes associated with other bacterial pathogens both within the urinary tract and elsewhere within the host.

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“…TosA is the most recently characterised toxin of UPEC (Vigil et al, 2012). Pic, Sat and Vat are ~110KDa secreted proteins and belong to the serine protease autotransporters of Enterobacteriaceae (SPATE) protein family.…”

Section: Toxinsmentioning

confidence: 99%

Autotransporter proteins of Uropathogenic Escherichia coli: regulation, characterisation and the role of periplasmic proteins in their expression

Nichols¹

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Uropathogenic Escherichia coli (UPEC) are the primary cause for all urinary tract infections.Autotransporter (AT) proteins are virulence factors secreted by the type V secretion pathway. This project examined the prevalence, regulation and expression of the vacuolating AT toxin (Vat), and the role of periplasmic chaperone proteins in AT translocation.The vacuolating autotransporter (AT) toxin (Vat) contributes to Uropathogenic Escherichia coli (UPEC) fitness during systemic infection. Vat is a serine protease AT of Enterobacteriaceae (SPATE) with cytotoxic activity. Here we characterised Vat and investigated its regulation in UPEC.We assessed the prevalence of vat in a collection of 45 UPEC urosepsis strains and showed it that was present in 31 (68%) of the isolates. The isolates containing the vat gene corresponded to three major E. coli sequence types (ST12, 73 and 95) and these strains secreted the Vat protein.Further analysis of the vat genetic locus identified a conserved gene located directly downstream of vat that encodes a putative MarR-like transcriptional regulator, which we termed vatX. The vatvatX genes were present in the UPEC reference strain CFT073 and RT-PCR revealed both genes are co-transcribed. Over-expression of vatX in CFT073 led to a 3-fold increase in vat gene transcription. The vat promoter region contained three putative nucleation sites for the global transcriptional regulator H-NS; thus the hns gene was mutated in CFT073 (to generate CFT073hns).Western blot analysis using a Vat-specific antibody revealed a significant increase in Vat expression in CFT073hns compared to wild-type CFT073. Direct H-NS binding to the vat promoter region was demonstrated using purified H-NS in combination with electrophoresis mobility shift assays. Finally, Vat-specific antibodies were detected in plasma samples from urosepsis patients iv Declaration by authorThis thesis is composed of my original work, and contains no material previously published or written by another person except where due reference has been made in the text. I have clearly stated the contribution by others to jointly-authored works that I have included in my thesis.

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The Repeat-In-Toxin Family Member TosA Mediates Adherence of Uropathogenic Escherichia coli and Survival during Bacteremia

Cited by 50 publications

References 42 publications

Regulation of Expression of Uropathogenic Escherichia coli Nonfimbrial Adhesin TosA by PapB Homolog TosR in Conjunction with H-NS and Lrp

Regulation of Expression of Uropathogenic Escherichia coli Nonfimbrial Adhesin TosA by PapB Homolog TosR in Conjunction with H-NS and Lrp

Strengths and Limitations of Model Systems for the Study of Urinary Tract Infections and Related Pathologies

Autotransporter proteins of Uropathogenic Escherichia coli: regulation, characterisation and the role of periplasmic proteins in their expression

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