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

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-w...

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Main Authors: Petra Horvatek, Andrea Salzer, Andrew Magdy Fekry Hanna, Fabio Lino Gratani, Daniela Keinhörster, Natalya Korn, Marina Borisova, Christoph Mayer, Dominik Rejman, Ulrike Mäder, Christiane Wolz
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2020-12-01
Series:PLoS Genetics
Online Access:https://doi.org/10.1371/journal.pgen.1009282
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author Petra Horvatek
Andrea Salzer
Andrew Magdy Fekry Hanna
Fabio Lino Gratani
Daniela Keinhörster
Natalya Korn
Marina Borisova
Christoph Mayer
Dominik Rejman
Ulrike Mäder
Christiane Wolz
author_facet Petra Horvatek
Andrea Salzer
Andrew Magdy Fekry Hanna
Fabio Lino Gratani
Daniela Keinhörster
Natalya Korn
Marina Borisova
Christoph Mayer
Dominik Rejman
Ulrike Mäder
Christiane Wolz
author_sort Petra Horvatek
collection DOAJ
description 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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spelling doaj.art-64b54852d2cc4a109726ec504c086cee2022-12-21T22:00:33ZengPublic Library of Science (PLoS)PLoS Genetics1553-73901553-74042020-12-011612e100928210.1371/journal.pgen.1009282Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes.Petra HorvatekAndrea SalzerAndrew Magdy Fekry HannaFabio Lino GrataniDaniela KeinhörsterNatalya KornMarina BorisovaChristoph MayerDominik RejmanUlrike MäderChristiane WolzThe 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.https://doi.org/10.1371/journal.pgen.1009282
spellingShingle Petra Horvatek
Andrea Salzer
Andrew Magdy Fekry Hanna
Fabio Lino Gratani
Daniela Keinhörster
Natalya Korn
Marina Borisova
Christoph Mayer
Dominik Rejman
Ulrike Mäder
Christiane Wolz
Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes.
PLoS Genetics
title Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes.
title_full Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes.
title_fullStr Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes.
title_full_unstemmed Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes.
title_short Inducible expression of (pp)pGpp synthetases in Staphylococcus aureus is associated with activation of stress response genes.
title_sort inducible expression of pp pgpp synthetases in staphylococcus aureus is associated with activation of stress response genes
url https://doi.org/10.1371/journal.pgen.1009282
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