A Putative Microcin Amplifies Shiga Toxin 2a Production of Escherichia coli O157:H7

Mosso, Hillary M.; Xiaoli, Lingzi; Banerjee, Kakolie; Hoffmann, Maria; Yao, Kuan; Dudley, Edward G.

doi:10.1128/jb.00353-19

Cited by 10 publications

(41 citation statements)

References 90 publications

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“…Stx2a levels are increased upon growth in supernatants of E. coli 0.1229 ∆B17::FRT E. coli strain 0.1229 produces two microcins: microcin B17 and the lesser characterized Mcc1229 (15). To isolate the impact of Mcc1229, we deleted the microcin B17 operon by onestep recombination, generating 0.1229 ∆B17::FRT.…”

Section: Resultsmentioning

confidence: 99%

“…Microcin B17, which is encoded on a 96.3 kb plasmid in 0.1229, contributed to but was not fully responsible for SOS induction or Stx amplification (15). An additional factor with Stxamplifying activity was localized to p0.1229_3, a 12.9 kb plasmid in the strain (15). This activity was dependent on TolC for efflux from 0.1229 and TonB for import into the target cell (15).…”

Section: Introductionmentioning

confidence: 99%

“…Prior studies of the human E. coli isolate 0.1229 revealed that cell-free supernatants from this strain were sufficient to induce the SOS response and increase the Stx expression of EHEC (15). Microcin B17, which is encoded on a 96.3 kb plasmid in 0.1229, contributed to but was not fully responsible for SOS induction or Stx amplification (15). An additional factor with Stxamplifying activity was localized to p0.1229_3, a 12.9 kb plasmid in the strain (15).…”

Section: Introductionmentioning

confidence: 99%

“…CFT073), and the lineage carries many virulence factors that can promote colonization and persistence in vivo (41,42). In 0.1229, MccB17 and Mcc1229 may serve this purpose, as they are lethal to competing E. coli strains (15).…”

Section: Introductionmentioning

confidence: 99%

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Mcc1229, an Stx2a-amplifying microcin, is produced in vivo and requires CirA for activity

Nawrocki¹,

Hutchins

Eaton

et al. 2021

Preprint

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Enterohemorrhagic E. coli (EHEC) strains, including the foodborne pathogen E. coli O157:H7, are responsible for thousands of hospitalizations each year. Various environmental triggers can modulate pathogenicity in EHEC by inducing expression of Shiga toxin (Stx), which is encoded on a lambdoid prophage and transcribed together with phage late genes. Cell-free supernatants of the sequence type (ST) 73 E. coli strain 0.1229 are potent inducers of Stx2a production in EHEC, suggesting that 0.1229 secretes a factor that activates the SOS response and leads to phage lysis. We previously demonstrated that this factor, designated microcin (Mcc) 1229, was proteinaceous and plasmid-encoded. To further characterize Mcc1229 and support its classification as a microcin, we investigated its regulation, determined its receptor, and identified loci providing immunity. Production of Mcc1229 was increased upon iron limitation, as determined by ELISA, lacZ fusions, and qRT-PCR. Spontaneous Mcc1229-resistant mutants and targeted gene deletion revealed that CirA was the Mcc1229 receptor. TonB, which interacts with CirA in the periplasm, was also essential for Mcc1229 import. Subcloning of the Mcc1229 plasmid indicated that Mcc activity was neutralized by two ORFs, each predicted to encode a domain of unknown function (DUF)-containing protein. In a germfree mouse model of infection, colonization with 0.1229 suppressed subsequent colonization of EHEC. Although Mcc1229 was produced in vivo, it was dispensable for colonization suppression. The regulation, import, and immunity determinants identified here are consistent with features of other Mccs, suggesting that Mcc1229 be included in this class of small molecules.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mcc1229, an Stx2a-amplifying microcin, is produced in vivo and requires CirA for activity

Nawrocki¹,

Hutchins

Eaton

et al. 2021

Preprint

Self Cite

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“…The coculture of O157:H7 with phage-susceptible strains can result in increased Shiga toxin production in vitro and in vivo (18)(19)(20). Furthermore, microcin, a bacteriocin also produced by Nissle, has been shown to increase Shiga toxin production by an SOS-dependent pathway (35), similar to the way in which the antibiotic ciprofloxacin induces Shiga toxin production (19). Our demonstration that Nissle is phage susceptible and that lysogens can produce Shiga toxin seriously compromises the use of Nissle as a therapeutic.…”

Section: Downloaded Frommentioning

confidence: 99%

Probiotic Properties of Escherichia coli Nissle in Human Intestinal Organoids

Pradhan

Weiss

2020

mBio

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ABSTRACT Escherichia coli strain Nissle has been used as a probiotic and therapeutic agent for over a century. Reports suggest that Nissle protects mice from enterohemorrhagic E. coli (EHEC) O157:H7 strains; however, mice are not very susceptible to O157:H7 and are not accurate models for O157:H7 infection in humans. Also, Nissle is closely related to uropathogenic E. coli (UPEC) strain CFT073, suggesting that Nissle could have pathogenic potential. To assess the safety of and protection conferred by Nissle, we modeled infection in stem cell-derived human intestinal organoids (HIOs). HIOs replicate the structure and function of human intestinal tissue. HIOs have a lumen enclosed by a single cell layer of differentiated epithelium, which is surrounded by a diffuse mesenchymal layer. An epithelial barrier which excludes the luminal contents from the surrounding cell layers and medium develops. Nissle appeared to be nonpathogenic; 103 CFU were microinjected into the lumen, and after 3 days, 107 CFU were recovered and the epithelial barrier remained intact. In contrast, microinjected EHEC and UPEC bacteria destroyed the epithelial barrier. To assess the protection conferred by Nissle, HIOs microinjected with Nissle were challenged after 18 to 24 h with EHEC or UPEC. Preincubation with Nissle prevented the loss of the epithelial barrier function, the loss of E-cadherin expression, the increased production of reactive oxygen species, and apoptosis. Nissle did not replicate in the HIO coculture, while the pathogenic strains did replicate, suggesting that Nissle conferred protection via activation of host defenses and not by eliminating competing strains. Nissle was shown to be susceptible to some Shiga toxin phage, and Nissle lysogens could produce Shiga toxin. IMPORTANCE Probiotic, or beneficial, bacteria, such as E. coli Nissle, hold promise for the treatment of human disease. More study is needed to fully realize the potential of probiotics. Safety and efficacy studies are critically important; however, mice are poor models for many human intestinal diseases. We used stem cell-derived human intestinal organoid tissues to evaluate the safety of Nissle and its ability to protect from pathogenic E. coli bacteria. Nissle was found to be safe. Human intestinal tissues were not harmed by the Nissle bacteria introduced into the digestive tract. In contrast, pathogenic E. coli bacteria destroyed the intestinal tissues, and importantly, Nissle conferred protection from the pathogenic E. coli bacteria. Nissle did not kill the pathogenic E. coli bacteria, and protection likely occurred via the activation of human defenses. Human intestinal tissues provide a powerful way to study complex host-microbe interactions.

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Microcins reveal natural mechanisms of bacterial manipulation to inform therapeutic development

Parker

Davies

2022

Microbiology

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Microcins are an understudied and poorly characterized class of antimicrobial peptides. Despite the existence of only 15 examples, all identified from the Enterobacteriaceae , microcins display diversity in sequence, structure, target cell uptake, cytotoxic mechanism of action and target specificity. Collectively, these features describe some of the unique means nature has contrived for molecules to cross the ‘impermeable’ barrier of the Gram-negative bacterial outer membrane and inflict cytotoxic effects. Microcins appear to be widely dispersed among different species and in different environments, where they function in regulating microbial communities in diverse ways, including through competition. Growing evidence suggests that microcins may be adapted for therapeutic uses such as antimicrobial drugs, microbiome modulators or facilitators of peptide uptake into cells. Advancing our biological, ecological and biochemical understanding of the roles of microcins in bacterial interactions, and learning how to regulate and modify microcin activity, is essential to enable such therapeutic applications.

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A Putative Microcin Amplifies Shiga Toxin 2a Production of Escherichia coli O157:H7

Cited by 10 publications

References 90 publications

Mcc1229, an Stx2a-amplifying microcin, is produced in vivo and requires CirA for activity

Mcc1229, an Stx2a-amplifying microcin, is produced in vivo and requires CirA for activity

Probiotic Properties of Escherichia coli Nissle in Human Intestinal Organoids

Microcins reveal natural mechanisms of bacterial manipulation to inform therapeutic development

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