Purine Nucleosides Interfere with c-di-AMP Levels and Act as Adjuvants To Re-Sensitize MRSA To β-Lactam Antibiotics

Nolan, Aaron; Zeden, Merve S; Kviatkovski, Igor; Campbell, Christopher; Urwin, Lucy; Corrigan, Rebecca M.; Gründling, Angelika; O’Gara, James P.

doi:10.1128/mbio.02478-22

Cited by 29 publications

(36 citation statements)

References 66 publications

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“…Single-cell time-lapse microscopy revealed that the increased c-di-AMP level in the ∆gdpP mutant did not impact its generation time indicating that the smaller cell volume is responsible for the reduced growth detected by OD measurements. These findings are in line with a recent study showing an increase in cell size in S. aureus JE2 correlated with an increase in OD (29). The ∆gdpP/∆pde2 and dacA G206S mutants showed a longer generation time indicating a c-di-AMP optimum concentration range for unimpaired growth.…”

Section: Discussionsupporting

confidence: 92%

“…However, the majority of these mecA-negative clinical isolates had acquired mutations in gdpP, indicating a clinical relevance of strains with increased c-di-AMP levels. Confirming earlier studies, we found drastically increased MICs for the beta-lactam oxacillin in the ΔgdpP and ΔgdpP/Δpde2 mutants and a decreased MIC in the dacA G206S mutant (3,8,9,29,33). In clinics, cephalosporins are often used to treat MRSA infections as they exhibit high affinity to the MRSA-specific PBP2a.…”

Section: Discussionsupporting

confidence: 89%

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C-di-AMP levels modulateStaphylococcus aureuscell wall thickness as well as virulence and contribute to antibiotic resistance and tolerance

Haunreiter

Tarnutzer

Bär

et al. 2023

Preprint

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Beta-lactam antibiotics are widely used to treat infections caused by the important human pathogen Staphylococcus aureus. Resistance to beta-lactams, as found in methicillin-resistant S. aureus (MRSA), renders effective treatment difficult. The second messenger cyclic di-3′,5′-adenosine monophosphate (c-di-AMP) promotes beta-lactam resistance in clinical S. aureus isolates. C-di-AMP plays a crucial role in the regulation of cellular processes such as virulence, cell wall homeostasis and resistance to beta-lactams in many bacterial species. In S. aureus, c-di-AMP synthesis is mediated by the diadenylate cyclase DacA, while its degradation is carried out by the phosphodiesterases GdpP and Pde2. In this work, we assessed the effect of altered c-di-AMP levels due to mutations in cacA, gdpP or gdpP/pde2 on virulence determinants. We report that a previously described growth defect in bacteria producing high c-di-AMP levels is mainly attributable to smaller cell size. High c-di-AMP levels also led to decreased survival upon oxidative stress, reduced production of the antioxidant staphyloxanthin, increased oxacillin and fosfomycin resistance and increased cell wall thickness. While resistance to ceftaroline was not affected, high c-di-AMP levels promoted tolerance to this antibiotic. In response to cell wall stress induced by antibiotics, the three-component regulatory system VraTSR mediates an increase in cell wall synthesis via the cell wall stress stimulon (CWSS). Increased c-di-AMP levels led to an activation of the CWSS. Upon deletion of vraR, resistance to oxacillin and fosfomycin as well as cell wall thickness diminished in the ΔgdpP mutant, indicating a contribution of the VraTSR system to the cell wall related phenotypes.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 89%

C-di-AMP levels modulateStaphylococcus aureuscell wall thickness as well as virulence and contribute to antibiotic resistance and tolerance

Haunreiter

Tarnutzer

Bär

et al. 2023

Preprint

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“…Extrapolating from previous data showing that purine metabolism controls β-lactam resistance (26, 41, 53–56), we turned our attention to the PPP, which produces ribose-5-P, a major substrate for purine and pyrimidine biosynthesis (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

“…We and others have previously reported that purine nucleotide homeostasis plays a key role in the regulation of β-lactam resistance in MRSA (49–53). Mutations in the pur operon and purine salvage pathway were associated with increased resistance, whereas exposure of MRSA to the purine nucleosides guanosine or xanthosine reduced β-lactam resistance (53).…”

Section: Introductionmentioning

confidence: 92%

“…Mutations in the pur operon and purine salvage pathway were associated with increased resistance, whereas exposure of MRSA to the purine nucleosides guanosine or xanthosine reduced β-lactam resistance (53). The purine-derived second messenger signalling molecules (p)ppGpp and c-di-AMP regulate β-lactam resistance, and exposure to exogenous guanosine downregulated c-di-AMP levels in S. aureus (53).…”

Section: Introductionmentioning

confidence: 99%

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Metabolic reprogramming and flux to cell envelope precursors in a pentose phosphate pathway mutant increases MRSA resistance to β-lactam antibiotics

Zeden

Gallagher

Cendejas-Bueno

et al. 2023

Preprint

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Central metabolic pathways controls virulence and antibiotic resistance, and constitute potential targets for antibacterial drugs. In Staphylococcus aureus the role of the pentose phosphate pathway (PPP) remains largely unexplored. Mutation of the 6-phosphogluconolactonase gene pgl, which encodes the only non-essential enzyme in the oxidative phase of the PPP, significantly increased MRSA resistance to β-lactam antibiotics, particularly in chemically defined media with glucose, and reduced oxacillin (OX)-induced lysis. Expression of the methicillin-resistance penicillin binding protein 2a and peptidoglycan architecture were unaffected. Carbon tracing and metabolomics revealed extensive metabolic reprogramming in the pgl mutant including increased flux to glycolysis, the TCA cycle, and several cell envelope precursors, which was consistent with increased β-lactam resistance. Morphologically, pgl mutant cells were smaller than wild-type with a thicker cell wall and ruffled surface when grown in OX. Further evidence of the pleiotropic effect of the pgl mutation was reduced resistance to Congo Red, sulfamethoxazole and oxidative stress, and increased resistance to targocil, fosfomycin and vancomycin. Reduced binding of wheat germ agglutinin (WGA) to pgl was indicative of lower wall teichoic acid/lipoteichoic acid levels or altered teichoic acid structures. Mutations in the vraFG or graRS loci reversed the increased OX resistance phenotype and restored WGA binding to wild-type levels. VraFG/GraRS was previously implicated in susceptibility to cationic antimicrobial peptides and vancomycin, and these data reveal a broader role for this multienzyme membrane complex in the export of cell envelope precursors or modifying subunits required for resistance to diverse antimicrobial agents. Altogether our study highlights important roles for the PPP and VraFG/GraRS in β-lactam resistance, which will support efforts to identify new drug targets and reintroduce β-lactams in combination with adjuvants or other antibiotics for infections caused by MRSA and other β-lactam resistant pathogens.

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Resensitizing β‐Lactams by Reprogramming Purine Metabolism in Small Colony Variant for Osteomyelitis Treatment

Shi,

Wu,

Ruan

et al. 2024

Advanced Science

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Small colony variant (SCV) is strongly linked to antibiotic resistance and the persistence of osteomyelitis. However, the intrinsic phenotypic instability of SCV has hindered a thorough investigation of its pathogenic mechanisms. In this study, phenotypically stable SCV strains are successfully recovered from clinical specimens, characterized by elevated drug resistance and reduced immunogenicity. Multi‐omics analysis revealed that the acquired high drug resistance is associated with altered flux in the purine metabolism pathway, attributable to mutations in the hypoxanthine phosphoribosyltransferase (hpt) gene. Furthermore, this study innovatively discovered that lonidamine, an inhibitor of cellular energy metabolism, can effectively mitigate SCV resistance to β‐lactam antibiotics, thereby facilitating its eradication. The underlying mechanism involves the reprogramming of purine metabolism. Therefore, a co‐delivery system for lonidamine and oxacillin is constructed with amino‐modified dendritic mesoporous silica as a carrier, which showed high efficacy and safety in combating SCV both in vitro and in vivo experiments. Overall, this study elucidated the pathogenic mechanisms of a class of clinically isolated SCV isolates with hpt mutations and provided a paradigm for treating SCV‐associated osteomyelitis by reprogramming purine metabolism.

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Purine Nucleosides Interfere with c-di-AMP Levels and Act as Adjuvants To Re-Sensitize MRSA To β-Lactam Antibiotics

Cited by 29 publications

References 66 publications

C-di-AMP levels modulateStaphylococcus aureuscell wall thickness as well as virulence and contribute to antibiotic resistance and tolerance

C-di-AMP levels modulateStaphylococcus aureuscell wall thickness as well as virulence and contribute to antibiotic resistance and tolerance

Metabolic reprogramming and flux to cell envelope precursors in a pentose phosphate pathway mutant increases MRSA resistance to β-lactam antibiotics

Resensitizing β‐Lactams by Reprogramming Purine Metabolism in Small Colony Variant for Osteomyelitis Treatment

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