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Bacterial persistence - Bacterial persistence is an active σS stress response to metabolic flux limitation

ABSTRACT: Bacterial persistence, found in dormant and starved cells, is a health threat due to transient antibiotic tolerance. Harnessing a novel method for persister generation, we determined the proteome, metabolite levels and the physiology of E.coli persisters in and during entry into dormancy and starvation. In contrast to starved persisters, dormant persisters present in nutrient-rich conditions produced energy and grew, while both types had extremely low metabolite pools. The proteome of dormant cells governed by starvation response reached a unique state characterized by diminished anabolism, stress response and preservation of central metabolism protein levels. While starved cells approaches the same proteome, the limited carbon and energy source did not allow them to reach it, which caused their higher sensitivity to certain antibiotics. We present a conceptual model in which depleted metabolite pools resulting from initial persistence triggers provide a primitive, feed-forward starvation signal that sustains the growing persistent phenotype.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Escherichia Coli

TISSUE(S): Permanent Cell Line Cell, Cell Culture

DISEASE(S): Mixed Disorder As Reaction To Stress

SUBMITTER: Alexander Schmidt

LAB HEAD: Alexander Schmidt

PROVIDER: PXD001968 | Pride | 2016-09-27

REPOSITORIES: Pride

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Bacterial persistence is an active σS stress response to metabolic flux limitation.

Radzikowski Jakub Leszek JL Vedelaar Silke S Siegel David D Ortega Álvaro Dario ÁD Schmidt Alexander A Heinemann Matthias M

Molecular systems biology 20160921 9

While persisters are a health threat due to their transient antibiotic tolerance, little is known about their phenotype and what actually causes persistence. Using a new method for persister generation and high-throughput methods, we comprehensively mapped the molecular phenotype of Escherichia coli during the entry and in the state of persistence in nutrient-rich conditions. The persister proteome is characterized by σ(S)-mediated stress response and a shift to catabolism, a proteome that starv ...[more]

PMID: 27655400

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Project description:Staphylococcus aureus causes invasive infections and easily acquires antibiotic resistances. Even antibiotic susceptible S. aureus can survive antibiotic therapy and persist, requiring prolonged treatment and surgical interventions. These so-called persisters display an arrested-growth phenotype, tolerate high antibiotic concentrations and are associated with chronic and recurrent infections. To characterize these persisters, we assessed S. aureus recovered directly from a patient suffering from a persistent infection. We show that host-mediated stress, including acidic-pH, abscesses-environment, and antibiotic exposure promoted persister formation in-vitro and in-vivo. Multi-omics analysis identified molecular changes in S. aureus in response to acid-stress leading to an overall virulent population. However, further analysis of a persister-enriched population revealed major molecular reprogramming in persisters including downregulation of virulence and cell division, and upregulation of ribosomal proteins, nucleotide-, and amino acid- metabolic pathways, suggesting their requirement to fuel and maintain the persister phenotype and highlighting that persisters are not completely metabolically inactive. Additionally, decreased aconitase activity and ATP-levels and accumulation of insoluble proteins involved in transcription, translation and energy-production correlated with persistence in S. aureus, underpinning the molecular mechanisms that drive the persister phenotype. Upon regrowth, these persisters regained their virulence potential and metabolically active phenotype including reduction of insoluble proteins, exhibiting a reversible state, crucial for recurrent infections. We further show that a targeted anti-persister combination therapy using retinoid derivatives and antibiotics significantly reduced lag-phase heterogeneity and persisters in a murine infection model. Our results provide molecular insights into persisters and help explain why persistent S. aureus infections are so difficult-to-treat.

Project description:Persisters are a subpopulation of metabolically-dormant cells in biofilms that are resistant to antibiotics; hence, understanding persister cell formation is important for controlling bacterial infections. Previously we discerned that MqsR and MqsA of Escherichia coli are a toxin/antitoxin pair that influence persister cell production via their regulation of Hha, CspD, and HokA. Here, to gain more insights into the origin of persisters, we used protein engineering to increase the toxicity of toxin MqsR by reasoning it would be easier to understand the effect of this toxin if it were more toxic. We found that two mutations (K3N and N31Y) increase the toxicity four fold and increase persistence 73 fold compared to native MqsR by making the protein less labile. A whole transcriptome study revealed that the MqsR variant represses acid resistance genes (gadABCEWX and hdeABD), multidrug resistance genes (mdtEF), and osmotic resistance genes (osmEY). Corroborating these microarray results, deletion of rpoS as well as the genes that the master stress response regulator RpoS controls, gadB, gadX, mdtF, and osmY, increased persister formation dramatically to the extent that nearly the whole population became persistent. Therefore, the more toxic MqsR increases persistence by decreasing the ability of the cell to respond to antibiotic stress through its RpoS-based regulation of acid resistance, multidrug resistance, and osmotic resistance systems. For the whole-transcriptome study of BW25113 mqsR/pBS(Kan)-mqsR 2-1 versus BW25113 mqsR/pBS(Kan)-mqsR, planktonic cells were grown to a turbidity of 0.5 at 600 nm in LB medium with 1 mM IPTG at 37 M-BM-0C, adjusted the turbidity to 1, and exposed to 20 M-NM-<g/mL ampicillin with 1 mM IPTG for 1 h. Cells were isolated by centrifuging at 0M-BM-0C, and RNALaterM-BM-. buffer (Ambion, Cat# AM7021) was added to stabilize RNA during the RNA preparation steps. Total RNA was isolated from cell pellets with Qiagen RNeasy mini Kit (Cat# 74104) using a bead beater. cDNA was synthesized and fragmented to obtain 50-200 base cDNA fragments. The fragmented cDNA was labelled with Biotin-ddUTP, and hybridization was performed at 45M-BM-0C with 60 rpm for 16 hours. The probe array was washed, stained using Affymetrix Genechip Fluidics Station 450 and the software GenomeChipOperating Software (GCOS)M-bM-^@M-^], and scanned using Affymetrix Genechip scanner GCS3000 7G system and the software GenomeChipOperating Software (GCOS). Data were processed with MAS 5.0 Expression Analysis Default Setting. Genes were identified as differentially expressed if the expression ratio was higher than the standard deviation: 4.0 fold (enriched and differentially degraded) cutoff for the DNA microarrays (standard deviation 1.3 fold), and if the p-value for comparing two chips was less than 0.05.

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