The alarmone (p)ppGpp confers tolerance to oxidative stress during the stationary phase by maintenance of redox and iron homeostasis in Staphylococcus aureus

Fritsch, Verena Nadin; Loi, Vu Van; Busche, Tobias; Tung, Quach Ngoc; Lill, Roland; Horvatek, Petra; Wolz, Christiane; Kalinowski, Jörn; Antelmann, Haike

doi:10.1016/j.freeradbiomed.2020.10.322

Cited by 32 publications

(31 citation statements)

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“…Genes whose expression is indicative of iron overload conditions were also highly affected by (pp)pGpp. We recently, could confirm that the (pp)pGpp 0 strain of strain USA300 has elevated free iron levels contributing to oxidative stress and increased ROS production [ 64 ]. A similar effect was reported for Vibrio cholera [ 65 ].…”

Section: Discussionmentioning

confidence: 99%

“…Here, the expression of the iron transporter FbpA was repressed via (pp)pGpp, resulting in a reduction of intracellular free iron required for the ROS-generating Fenton reaction. This contributed to reducing antibiotic-induced oxidative stress and thus tolerance, and this is also true for S. aureus [ 64 ]. In addition to interfering with iron metabolism, other genes involved in oxidative stress were activated by (pp)pGpp.…”

Section: Discussionmentioning

confidence: 99%

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Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes

et al. 2020

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The stringent response is characterized by the synthesis of the messenger molecules pppGpp, ppGpp or pGpp (here collectively designated (pp)pGpp). The phenotypic consequences resulting from (pp)pGpp accumulation vary among species and can be mediated by different underlying mechanisms. Most genome-wide analyses have been performed under stress conditions, which often mask the immediate effects of (pp)pGpp-mediated regulatory circuits. In Staphylococcus aureus, (pp)pGpp can be synthesized via the RelA-SpoT-homolog, RelSau upon amino acid limitation or via one of the two small (pp)pGpp synthetases RelP or RelQ upon cell wall stress. We used RNA-Seq to compare the global effects in response to induction of the synthetase of rel-Syn (coding for the enzymatic region of RelSau) or relQ without the need to apply additional stress conditions. Induction of rel-Syn resulted in changes in the nucleotide pool similar to induction of the stringent response via the tRNA synthetase inhibitor mupirocin: a reduction in the GTP pool, an increase in the ATP pool and synthesis of pppGpp, ppGpp and pGpp. Induction of all three enzymes resulted in similar changes in the transcriptome. However, RelQ was less active than Rel-Syn and RelP, indicating strong restriction of its (pp)pGpp-synthesis activity in vivo. (pp)pGpp induction resulted in the downregulation of many genes involved in protein and RNA/DNA metabolism. Many of the (pp)pGpp upregulated genes are part of the GTP sensitive CodY regulon and thus likely regulated through lowering of the GTP pool. New CodY independent transcriptional changes were detected including genes involved in the SOS response, iron storage (e.g. ftnA, dps), oxidative stress response (e.g., perR, katA, sodA) and the psmα1–4 and psmß1-2 operons coding for cytotoxic, phenol soluble modulins (PSMs). Analyses of the ftnA, dps and psm genes in different regulatory mutants revealed that their (pp)pGpp-dependent regulation can occur independent of the regulators PerR, Fur, SarA or CodY. Moreover, psm expression is uncoupled from expression of the quorum sensing system Agr, the main known psm activator. The expression of central genes of the oxidative stress response protects the bacteria from anticipated ROS stress derived from PSMs or exogenous sources. Thus, we identified a new link between the stringent response and oxidative stress in S. aureus that is likely crucial for survival upon phagocytosis.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes

et al. 2020

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“…Quinones differ by their redox potential: Ubiquinone has high midpoint We observed an increase during hyperbaric heliox saturation of certain defense mechanisms against oxidative stress involved in bacterial survival: ppGpp biosynthesis, pentose phosphate pathway, and mycothiol biosynthesis. ppGpp (guanosine tetraphosphate) is a stress signal molecule that is usually produced under conditions of nutrient starvation (Fritsch et al, 2020). Thiols play a major role in the detoxification of stressinducing factors, one of these thiols being glutathione (GSH).…”

Section: Discussionmentioning

confidence: 99%

Functional Profiling Reveals Altered Metabolic Activity in Divers’ Oral Microbiota During Commercial Heliox Saturation Diving

et al. 2021

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Background: The extreme environment in saturation diving affects all life forms, including the bacteria that reside on human skin and mucosa. The oral cavity alone is home to hundreds of different bacteria. In this study, we examined the metabolic activity of oral bacteria from healthy males during commercial heliox saturation diving. We focused on environmentally induced changes that might affect the divers’ health and fitness.Methods: We performed pathway abundance analysis using PICRUSt2, a bioinformatics software package that uses marker gene data to compute the metabolic activity of microbial communities. The analysis is based on 16S rRNA metagenomic data generated from the oral microbiota of 23 male divers before, during, and after 4weeks of commercial heliox saturation diving. Environmentally induced changes in bacterial metabolism were computed from differences in predicted pathway abundances at baseline before, versus during, and immediately after saturation diving.Results and Conclusion: The analysis predicted transient changes that were primarily associated with the survival and growth of bacteria in oxygenated environments. There was a relative increase in the abundance of aerobic metabolic pathways and a concomitant decrease in anaerobic metabolic pathways, primarily comprising of energy metabolism, oxidative stress responses, and adenosylcobalamin biosynthesis. Adenosylcobalamin is a bioactive form of vitamin B12 (vitB12), and a reduction in vitB12 biosynthesis may hypothetically affect the divers’ physiology. While host effects of oral bacterial vitamin metabolism are uncertain, this is a finding that concurs with the existing recommendations for vitB12 supplements as part of the divers’ diet, whether to boost antioxidant defenses in bacteria or their host or to improve oxygen transport during saturation diving.

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“…The multi-resistant S. aureus USA300JE2 strain ( Fey et al, 2013 ) was used for the AGXX® survival experiments and cultivated in RPMI medium as described ( Fritsch et al, 2020 ). For survival assays under AGXX® stress, S. aureus USA300JE2 was grown in RPMI medium to an optical density at 500 nm (OD 500 ) of 0.5 and exposed to 10–40 μg/ml AGXX®373 and 40–100 μg/ml AGXX®383 microparticles as indicated in the figure legends.…”

Section: Methodsmentioning

confidence: 99%

“…The multi-resistant S. aureus USA300JE2 strain (Fey et al, 2013) was used for the AGXX ® survival experiments and cultivated in RPMI medium as described (Fritsch et al, 2020).…”

Section: Bacterial Cultivation and Survival Assaysmentioning

confidence: 99%

The Antimicrobial Activity of the AGXX® Surface Coating Requires a Small Particle Size to Efficiently Kill Staphylococcus aureus

Linzner

Antelmann

2021

Front. Microbiol.

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Methicillin-resistant Staphylococcus aureus (MRSA) isolates are often resistant to multiple antibiotics and pose a major health burden due to limited treatment options. The novel AGXX® surface coating exerts strong antimicrobial activity and successfully kills multi-resistant pathogens, including MRSA. The mode of action of AGXX® particles involves the generation of reactive oxygen species (ROS), which induce an oxidative and metal stress response, increased protein thiol-oxidations, protein aggregations, and an oxidized bacillithiol (BSH) redox state in S. aureus. In this work, we report that the AGXX® particle size determines the effective dose and time-course of S. aureus USA300JE2 killing. We found that the two charges AGXX®373 and AGXX®383 differ strongly in their effective concentrations and times required for microbial killing. While 20–40 μg/ml AGXX®373 of the smaller particle size of 1.5–2.5 μm resulted in >99.9% killing after 2 h, much higher amounts of 60–80 μg/ml AGXX®383 of the larger particle size of >3.2 μm led to a >99% killing of S. aureus USA300JE2 within 3 h. Smaller AGXX® particles have a higher surface/volume ratio and therefore higher antimicrobial activity to kill at lower concentrations in a shorter time period compared to the larger particles. Thus, in future preparations of AGXX® particles, the size of the particles should be kept at a minimum for maximal antimicrobial activity.

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The alarmone (p)ppGpp confers tolerance to oxidative stress during the stationary phase by maintenance of redox and iron homeostasis in Staphylococcus aureus

Cited by 32 publications

References 106 publications

Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes

Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes

Functional Profiling Reveals Altered Metabolic Activity in Divers’ Oral Microbiota During Commercial Heliox Saturation Diving

The Antimicrobial Activity of the AGXX® Surface Coating Requires a Small Particle Size to Efficiently Kill Staphylococcus aureus

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