Clinical Relevance of Type II Fatty Acid Synthesis Bypass in Staphylococcus aureus

Gloux, Karine; Guillemet, Mélanie; Soler, C.; Morvan, Claire; Halpern, David; Pourcel, Christine; Thien, H. Vu; Lamberet, Gilles; Gruss, Alexandra

doi:10.1128/aac.02515-16

Cited by 32 publications

(53 citation statements)

References 43 publications

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“…Recently, Gloux et al [90] addressed this question by collecting S. aureus samples for clinical and veterinary settings and plating them on selective media containing exogenous fatty acids and/or triclosan. They report 12% of 695 the isolates had modification in FASII genes.…”

Section: Evolutionary Changes In Bacterial Phospholipid Synthesis mentioning

confidence: 99%

Exogenous fatty acid metabolism in bacteria

2017

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Bacterial type II fatty acid synthesis (FASII) is a target for novel antibiotic development. All bacteria encode for mechanisms to incorporate exogenous fatty acids, and some bacteria can use exogenous fatty acids to bypass FASII inhibition. Bacteria encode three different mechanisms for activating exogenous fatty acids for incorporation into phospholipid synthesis. Exogenous fatty acids are converted into acyl-CoA in Gammaproteobacteria such as E. coli. Acyl-CoA molecules constitute a separate pool from endogenously synthesized acyl-ACP. Acyl-CoA can be used for phospholipid synthesis or broken down by β-oxidation, but cannot be used for lipopolysaccharide synthesis. Exogenous fatty acids are converted into acyl-ACP in some Gram-negative bacteria. The resulting acyl-ACP undergoes the same fates as endogenously synthesized acyl-ACP. Exogenous fatty acids are converted into acyl-phosphates in Gram-positive bacteria, and can be used for phospholipid synthesis or become acyl-ACP. Only the order Lactobacillales can use exogenous fatty acids to bypass FASII inhibition. FASII shuts down completely in presence of exogenous fatty acids in Lactobacillales, allowing Lactobacillales to synthesize phospholipids entirely from exogenous fatty acids. Inhibition of FASII cannot be bypassed in other bacteria because FASII is only partially down-regulated in presence of exogenous fatty acid or FASII is required to synthesize essential metabolites such as β-hydroxyacyl-ACP. Certain selective pressures such as FASII inhibition or growth in biofilms can select for naturally occurring one step mutations that attenuate endogenous fatty acid synthesis. Although attempts have been made to estimate the natural prevalence of these mutants, culture-independent metagenomic methods would provide a better estimate.

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Section: Evolutionary Changes In Bacterial Phospholipid Synthesis mentioning

confidence: 99%

Exogenous fatty acid metabolism in bacteria

2017

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“…Furthermore, when cultured in the presence of porcine liver extracts S. aureus bacteria with non-synonymous mutations in the malonyl CoA-acyl carrier protein transacylase ( fabD) gene bypass the FASII pathway and incorporate long-chain polyunsaturated fatty acids such as C20:4 into their membranes [36]. Examination of a large panel of clinical isolates has indicated that it could be a common strategy of S. aureus to incorporate exogenous FA, overcoming its reliance on endogenous FA biosynthesis, and thus rendering ineffective FASII inhibitors such as the widely used biocide triclosan [37].…”

Section: Resultsmentioning

confidence: 99%

Characterisation ofStaphylococcus aureuslipids by nanoelectrospray ionisation tandem mass spectrometry (nESI-MS/MS)

Young

Desbois

Coote

et al. 2019

Preprint

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19Staphylococcus aureus is a major opportunistic pathogen that is exposed to antimicrobial 20 innate immune effectors and antibiotics that can disrupt its cell membrane. An 21 understanding of S. aureus lipid composition and its role in defending the cell against 22 validated the molecular characterization and showed the principal species present in each 33 strain were predominately anteiso-and iso-branched chain fatty acids. Though the fatty acid 34 and lipid profiles were similar between the S. aureus strains, this method was sufficiently 35 sensitive to distinguish minor differences in lipid composition. In conclusion, this nESI-36 MS/MS methodology can characterise the role of lipids in antimicrobial resistance, and may 37 even be applied to the rapid diagnosis of drug-resistant strains in the clinic. 38 3 39 101 102 6 103 Materials and methods 104 S. aureus culture and lipid extraction 105 All reagents and culture media were purchased from Sigma-Aldrich Ltd. S. aureus Newman 106 (methicillin-susceptible; MSSA), BB270 (methicillin-resistant; MRSA) and Mu50 (MRSA and 107 vancomycin intermediate-resistant) were sourced and cultured in Müller-Hinton broth as 108 described previously [22]. Briefly, each bacterial strain was prepared by inoculation of a 109 colony from an agar plate into 10 ml Müller-Hinton broth and cultured at 37°C with shaking 110 until reaching an OD 600nm = 1 (~1 × 10 9 colony-forming units [cfu]). Bacterial cells were 111 harvested (1000 × g, 10 min), washed in PBS before a repeat centrifugation and removal of 112 the supernatant. Lipids were extracted according to the Bligh-Dyer method [23], dried under 113 nitrogen, and stored at 4°C until analysis by mass spectrometry. 114 115 157

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“…Adaptation to FASII inhibitors is not due to FASII mutations. Mutations in FASII initiation genes may 91 lead to antibiotic resistance (14,(17)(18)(19). We monitored mutations in FASII antibiotic-adapted USA300 92 or Newman strains by DNAseq, using FASII inhibitors triclosan or AFN-1252 (Table S1).…”

Section: Aureus 89 90mentioning

confidence: 99%

“…Anti-FASII 25 resistance due to mutations affecting the target enzyme or to horizontal transfer of an antibiotic-26 resistant gene homologue may occur and are often antibiotic-specific (15,16). In contrast, resistant 27 mutants that allow compensatory fatty acid utilization at both phospholipid positions were isolated 28 and also found in clinical isolates; these mutants map in FASII initiation genes distinct from the gene 29 encoding the antibiotic target protein (17)(18)(19). Despite emergence of mutations, continued FASII-30 targeted drug development is rationalized by the accepted postulate that the general wild type S. 31 aureus population must synthesize branched chain fatty acid anteiso 15:0 (ai15) to complete 32 membrane phospholipids (1, 3, 5, 8-11, 14, 20).…”

Section: Introduction 19 20mentioning

confidence: 99%

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Permissive Fatty Acid Incorporation in Host Environments Promotes Staphylococcal Adaptation to FASII Antibiotics

Kénanian

Morvan

Weckel

et al. 2019

Preprint

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1Development of fatty acid synthesis pathway (FASII) inhibitors against the major human pathogen 2 Staphylococcus aureus hinges on the accepted but unproven postulate that an endogenously 3 synthesized branched chain fatty acid is required to complete membrane phospholipids. Evidence for 4 anti-FASII efficacy in animal models supported this view. However, restricted test conditions used 5 previously to show FASII antibiotic efficacy led us to investigate these questions in a broader, host-6 relevant context. We report that S. aureus rapidly adapts to FASII antibiotics without FASII mutations 7 when exposed to host environments. Treatment with a lead FASII antibiotic upon signs of infection, 8 rather than just after inoculation as commonly practiced, failed to eliminate S. aureus from infected 9 organs in a septicemia model. In vitro, addition of serum facilitated rapid S. aureus FASII bypass by 10 environmental fatty acid (eFA) replacement in phospholipids. Serum lowers membrane stress, 11 leading to increased retention of the two substrates required for exogenous fatty acid (eFA) 12 utilization. In these conditions, eFA occupy both phospholipid positions 1 and 2, regardless of anti-13 FASII selection. This study revises conclusions on S. aureus fatty acid requirements by disproving the 14 postulate of fatty acid stringency, and reveals an Achilles' heel for using FASII antibiotics to treat 15 infection in monotherapy. 16 17 18 decreased 10-fold in liver (p= ≤0.05), and unchanged in spleen. FASII antibiotic treatments thus failed 54 to eliminate S. aureus in a septicemia model. The underlying mechanisms leading to FASII inhibitor 55 escape in host-relevant conditions were investigated. 56 57 Host constituents promote rapid staphylococcal adaptation to FASII antibiotics. We reasoned that 58 in septicemic infection, serum and other host constituents bind eFA, and may neutralize FASII 59 inhibitors (2, 5, 24,25). The effect of serum on FASII antibiotic activity was tested using triclosan, an 60 extensively studied and used biocide that also targets FabI (26). S. aureus triclosan sensitivity was 61 compared in medium containing a 3-fatty-acid cocktail (called here 'FA'; with triclosan, FA-Tric), and 62 the same medium supplemented with serum (SerFA-Tric)( Fig. 2A). USA300 and Newman strain 63 growth without serum were inhibited by triclosan, with emergence of FASII mutants usually after 24-64 48 h incubation (18). However, serum supplementation markedly shortened latency compared to BHI 65

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Clinical Relevance of Type II Fatty Acid Synthesis Bypass in Staphylococcus aureus

Cited by 32 publications

References 43 publications

Exogenous fatty acid metabolism in bacteria

Exogenous fatty acid metabolism in bacteria

Characterisation ofStaphylococcus aureuslipids by nanoelectrospray ionisation tandem mass spectrometry (nESI-MS/MS)

Permissive Fatty Acid Incorporation in Host Environments Promotes Staphylococcal Adaptation to FASII Antibiotics

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