Convergence of PASTA Kinase and Two-Component Signaling in Response to Cell Wall Stress in Enterococcus faecalis

Kellogg, Stephanie L.; Kristich, Christopher J.

doi:10.1128/jb.00086-18

Cited by 30 publications

(31 citation statements)

References 31 publications

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“…For example, we observed mutations in genes for drug targets associated with protein synthesis inhibitors ( rpsJ [66], 30S ribosomal protein S5 [ rpsE ] [67]) and fluoroquinolones (DNA topoisomerase 4 subunit A [ parC ]; DNA gyrase subunit A, [ gyrA ] [68]). We also identified mutations in a sensor histidine kinase [69, 70] ( EF3290 ) in populations selected by cell wall inhibitors and mutations in 23S rRNA genes in the LZD-selected population [64, 71]. Surprisingly, the DAP-selected population did not contain mutations in genes previously identified with DAP resistance [57, 58], though we observe a mutation in rpsJ in both the clonal and population sequences.…”

Section: Resultsmentioning

confidence: 84%

Pervasive and diverse collateral sensitivity profiles inform optimal strategies to limit antibiotic resistance

2019

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Evolved resistance to one antibiotic may be associated with "collateral" sensitivity to other drugs. Here, we provide an extensive quantitative characterization of collateral effects in Enterococcus faecalis, a gram-positive opportunistic pathogen. By combining parallel experimental evolution with high-throughput dose-response measurements, we measure phenotypic profiles of collateral sensitivity and resistance for a total of 900 mutant–drug combinations. We find that collateral effects are pervasive but difficult to predict because independent populations selected by the same drug can exhibit qualitatively different profiles of collateral sensitivity as well as markedly different fitness costs. Using whole-genome sequencing of evolved populations, we identified mutations in a number of known resistance determinants, including mutations in several genes previously linked with collateral sensitivity in other species. Although phenotypic drug sensitivity profiles show significant diversity, they cluster into statistically similar groups characterized by selecting drugs with similar mechanisms. To exploit the statistical structure in these resistance profiles, we develop a simple mathematical model based on a stochastic control process and use it to design optimal drug policies that assign a unique drug to every possible resistance profile. Stochastic simulations reveal that these optimal drug policies outperform intuitive cycling protocols by maintaining long-term sensitivity at the expense of short-term periods of high resistance. The approach reveals a new conceptual strategy for mitigating resistance by balancing short-term inhibition of pathogen growth with infrequent use of drugs intended to steer pathogen populations to a more vulnerable future state. Experiments in laboratory populations confirm that model-inspired sequences of four drugs reduce growth and slow adaptation relative to naive protocols involving the drugs alone, in pairwise cycles, or in a four-drug uniform cycle.

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Section: Resultsmentioning

confidence: 84%

Pervasive and diverse collateral sensitivity profiles inform optimal strategies to limit antibiotic resistance

2019

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“…The ireK encoded transmembrane Ser/Thr kinase regulates cell wall homeostasis, antimicrobial resistance, and contributes to bacterial fitness during long-term colonization of the intestinal tract [61, 67, 68]. Recently it has been shown that direct cross-talk between IreK and the CroS/R system positively impacts enterococcal cephalosporin resistance [69].…”

Section: Resultsmentioning

confidence: 99%

Phage infection and sub-lethal antibiotic exposure mediateEnterococcus faecalistype VII secretion system dependent inhibition of bystander bacteria

Chatterjee

Willett

Dunny

et al. 2020

Preprint

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Enterococci constitute a minor component of the healthy human microbiota (1). Enterococci, 54 including Enterococcus faecalis, are also nosocomial pathogens that cause a variety of diseases, 55 including sepsis, endocarditis, surgical-site, urinary tract and mixed bacterial infections (2, 3). 56Over recent decades, enterococci have acquired extensive antibiotic resistance traits, including 57 resistance to "last-resort" antibiotics such as vancomycin, daptomycin, and linezolid (4-8). 58Following antibiotic therapy, multi-drug resistant (MDR) enterococci can outgrow to become a 59 dominant member of the intestinal microbiota, resulting in intestinal barrier invasion and blood 60 stream infection (7, 9). The ongoing evolution of MDR enterococci in healthcare settings (4-6, 10, 61 11) and their ability to transmit antibiotic resistance among diverse bacteria (9, 12-15), emphasize 62 the immediate need for novel therapeutic approaches to control enterococcal infections. 63Viruses that infect and kill bacteria (bacteriophages or phages) are receiving attention for their 64 use as antibacterial agents (16). Recent studies have demonstrated the efficacy of anti-65 enterococcal phages in murine models of bacteremia (17)(18)(19) and the administration of phages to 66 reduce E. faecalis burden in the intestine gives rise to phage resistant isolates that are 67 resensitized to antibiotics (20). Considering phages are highly specific for their target bacterium, 68 coupled with the self-limiting nature of their host-dependent replication, suggests that unlike 69 antibiotics which have broad off-target antimicrobial activity, phages are likely to have nominal 70 impact on bacteria outside of their intended target strain (21-23). However, our understanding of 71 how phages interact with bacteria and the bacterial response to phage infection is limited. 72While studying the transcriptional response of phage infected E. faecalis cells, we discovered 73 that phage infection induced the expression of genes involved in the biosynthesis of a type VIIb 74 secretion system (T7SS) (24). Firmicutes, including the enterococci, harbor diverse T7SS genes 75 encoding transmembrane and cytoplasmic proteins involved in the secretion of protein substrates 76 (25), and T7SSs promote antagonism of non-kin bacterial cells through contact-dependent 77 secretion of antibacterial effectors and/or toxins (26, 27). The antibacterial activity of T7SSs from 78 96 Results 97 Phage mediated induction of E. faecalis T7SS leads to interspecies antagonism. 98A hallmark feature of phage therapy is that because phages often have a narrow host range, 99 they will not influence the growth of non-susceptible bacteria occupying the same niche (22). We 100 discovered that infection of E. faecalis OG1RF by phage VPE25, induces the expression of T7SS 101 genes (24). The E. faecalis OG1RF T7SS locus is absent in the commonly studied vancomycin-102 resistant strain V583, despite conservation of flanking genes (Fig. 1A) (32, 33). Homologs of the 103 E. faecalis T7SS ...

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“…Here, we show that all three epa mutants exhibit significantly increased resistance to ceftriaxone, a type of cephalosporin. It has been previously reported that intrinsic cephalosporin resistance is mediated by a eukaryotic-like Ser/Thr kinase, IreK, formerly known as PrkC (29), and by the CroRS two-component regulatory system (30), and that these two signaling systems are intertwined (31). IreK is thought to monitor cell wall integrity and respond to cell wall stress (29).…”

Section: Discussionmentioning

confidence: 99%

Role of epaQ , a Previously Uncharacterized Enterococcus faecalis Gene, in Biofilm Development and Antimicrobial Resistance

2019

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Enterococcus faecalis is a commensal of the human gastrointestinal tract; it is also an opportunistic pathogen and one of the leading causes of hospital-acquired infections. E. faecalis produces biofilms that are highly resistant to antibiotics, and it has been previously reported that certain genes of the epa operon contribute to biofilm-associated antibiotic resistance. Despite several studies examining the epa operon, many gene products of this operon remain annotated as hypothetical proteins. Here, we further explore the epa operon; we identified epaQ, currently annotated as encoding a hypothetical membrane protein, as being important for biofilm formation in the presence of the antibiotic daptomycin. Mutants with disruptions of epaQ were more susceptible to daptomycin relative to the wild type, suggesting its importance in biofilm-associated antibiotic resistance. Furthermore, the ΔepaQ mutant exhibited an altered biofilm architectural arrangement and formed small aggregates in liquid cultures. Our cumulative data show that epa mutations result in altered polysaccharide content, increased cell surface hydrophobicity, and decreased membrane potential. Surprisingly, several epa mutations significantly increased resistance to the antibiotic ceftriaxone, indicating that the way in which the epa operon impacts antibiotic resistance is antibiotic dependent. These results further define the key role of epa in antibiotic resistance in biofilms and in biofilm architecture. IMPORTANCE E. faecalis is a common cause of nosocomial infection, has a high level of antibiotic resistance, and forms robust biofilms. Biofilm formation is associated with increased antibiotic resistance. Therefore, a thorough understanding of biofilm-associated antibiotic resistance is important for combating resistance. Several genes from the epa operon have previously been implicated in biofilm-associated antibiotic resistance, pathogenesis, and competitive fitness in the GI tract, but most genes in this locus remain uncharacterized. Here, we examine epaQ, which has not been characterized functionally. We show that the ΔepaQ mutant exhibits reduced biofilm formation in the presence of daptomycin, altered biofilm architecture, and increased resistance to ceftriaxone, further expanding our understanding of the contribution of this operon to intrinsic enterococcal antibiotic resistance and biofilm growth.

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Convergence of PASTA Kinase and Two-Component Signaling in Response to Cell Wall Stress in Enterococcus faecalis

Cited by 30 publications

References 31 publications

Pervasive and diverse collateral sensitivity profiles inform optimal strategies to limit antibiotic resistance

Pervasive and diverse collateral sensitivity profiles inform optimal strategies to limit antibiotic resistance

Phage infection and sub-lethal antibiotic exposure mediateEnterococcus faecalistype VII secretion system dependent inhibition of bystander bacteria

Role of epaQ , a Previously Uncharacterized Enterococcus faecalis Gene, in Biofilm Development and Antimicrobial Resistance

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