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Baruzzo G, Serafini A, Finotello F, Sanavia T, Cioetto-Mazzabò L, Boldrin F, Lavezzo E, Barzon L, Toppo S, Provvedi R, Manganelli R, Di Camillo B. Role of the Extracytoplasmic Function Sigma Factor SigE in the Stringent Response of Mycobacterium tuberculosis. Microbiol Spectr 2023; 11:e0294422. [PMID: 36946740 PMCID: PMC10100808 DOI: 10.1128/spectrum.02944-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 02/15/2023] [Indexed: 03/23/2023] Open
Abstract
Bacteria respond to nutrient starvation implementing the stringent response, a stress signaling system resulting in metabolic remodeling leading to decreased growth rate and energy requirements. A well-characterized model of stringent response in Mycobacterium tuberculosis is the one induced by growth in low phosphate. The extracytoplasmic function (ECF) sigma factor SigE was previously suggested as having a key role in the activation of stringent response. In this study, we challenge this hypothesis by analyzing the temporal dynamics of the transcriptional response of a sigE mutant and its wild-type parental strain to low phosphate using RNA sequencing. We found that both strains responded to low phosphate with a typical stringent response trait, including the downregulation of genes encoding ribosomal proteins and RNA polymerase. We also observed transcriptional changes that support the occurring of an energetics imbalance, compensated by a reduced activity of the electron transport chain, decreased export of protons, and a remodeling of central metabolism. The most striking difference between the two strains was the induction in the sigE mutant of several stress-related genes, in particular, the genes encoding the ECF sigma factor SigH and the transcriptional regulator WhiB6. Since both proteins respond to redox unbalances, their induction suggests that the sigE mutant is not able to maintain redox homeostasis in response to the energetics imbalance induced by low phosphate. In conclusion, our data suggest that SigE is not directly involved in initiating stringent response but in protecting the cell from stress consequent to the low phosphate exposure and activation of stringent response. IMPORTANCE Mycobacterium tuberculosis can enter a dormant state enabling it to establish latent infections and to become tolerant to antibacterial drugs. Dormant bacteria's physiology and the mechanism(s) used by bacteria to enter dormancy during infection are still unknown due to the lack of reliable animal models. However, several in vitro models, mimicking conditions encountered during infection, can reproduce different aspects of dormancy (growth arrest, metabolic slowdown, drug tolerance). The stringent response, a stress response program enabling bacteria to cope with nutrient starvation, is one of them. In this study, we provide evidence suggesting that the sigma factor SigE is not directly involved in the activation of stringent response as previously hypothesized, but it is important to help the bacteria to handle the metabolic stress related to the adaptation to low phosphate and activation of stringent response, thus giving an important contribution to our understanding of the mechanism behind stringent response development.
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Affiliation(s)
- Giacomo Baruzzo
- Department of Information Engineering, University of Padova, Padua, Italy
| | - Agnese Serafini
- Department of Molecular Medicine, University of Padova, Padua, Italy
| | | | - Tiziana Sanavia
- Department of Information Engineering, University of Padova, Padua, Italy
| | | | - Francesca Boldrin
- Department of Molecular Medicine, University of Padova, Padua, Italy
| | - Enrico Lavezzo
- Department of Molecular Medicine, University of Padova, Padua, Italy
| | - Luisa Barzon
- Department of Molecular Medicine, University of Padova, Padua, Italy
| | - Stefano Toppo
- Department of Molecular Medicine, University of Padova, Padua, Italy
| | | | | | - Barbara Di Camillo
- Department of Information Engineering, University of Padova, Padua, Italy
- Department of Comparative Biomedicine and Food Science, University of Padova, Padua, Italy
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van Wijk RC, Lucía A, Sudhakar PK, Sonnenkalb L, Gaudin C, Hoffmann E, Dremierre B, Aguilar-Ayala DA, Dal Molin M, Rybniker J, de Giorgi S, Cioetto-Mazzabò L, Segafreddo G, Manganelli R, Degiacomi G, Recchia D, Pasca MR, Simonsson USH, Ramón-García S. Implementing best practises on data generation and reporting of Mycobacterium tuberculosis in vitro assays within the ERA4TB consortium. iScience 2023; 26:106411. [PMID: 37091238 PMCID: PMC10119593 DOI: 10.1016/j.isci.2023.106411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 11/14/2022] [Accepted: 03/10/2023] [Indexed: 03/17/2023] Open
Abstract
Tuberculosis (TB) is the historical leading cause of death by a single infectious agent. The European Regimen Accelerator for Tuberculosis (ERA4TB) is a public-private partnership of 30+ institutions with the objective to progress new anti-TB regimens into the clinic. Thus, robust and replicable results across independent laboratories are essential for reliable interpretation of treatment efficacy. A standardization workgroup unified in vitro protocols and data reporting templates. Time-kill assays provide essential input data for pharmacometric model-informed translation of single agents and regimens activity from in vitro to in vivo and the clinic. Five conditions were assessed by time-kill assays in six independent laboratories using four bacterial plating methods. Baseline bacterial burden varied between laboratories but variability was limited in net drug effect, confirming 2.5 μL equally robust as 100 μL plating. This exercise establishes the foundations of collaborative data generation, reporting, and integration within the overarching Antimicrobial Resistance Accelerator program.
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Manganelli R, Cioetto-Mazzabò L, Segafreddo G, Boldrin F, Sorze D, Conflitti M, Serafini A, Provvedi R. SigE: A master regulator of Mycobacterium tuberculosis. Front Microbiol 2023; 14:1075143. [PMID: 36960291 PMCID: PMC10027907 DOI: 10.3389/fmicb.2023.1075143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 02/16/2023] [Indexed: 03/09/2023] Open
Abstract
The Extracellular function (ECF) sigma factor SigE is one of the best characterized out of the 13 sigma factors encoded in the Mycobacterium tuberculosis chromosome. SigE is required for blocking phagosome maturation and full virulence in both mice and guinea pigs. Moreover, it is involved in the response to several environmental stresses as surface stress, oxidative stress, acidic pH, and phosphate starvation. Underscoring its importance in M. tuberculosis physiology, SigE is subjected to a very complex regulatory system: depending on the environmental conditions, its expression is regulated by three different sigma factors (SigA, SigE, and SigH) and a two-component system (MprAB). SigE is also regulated at the post-translational level by an anti-sigma factor (RseA) which is regulated by the intracellular redox potential and by proteolysis following phosphorylation from PknB upon surface stress. The set of genes under its direct control includes other regulators, as SigB, ClgR, and MprAB, and genes involved in surface remodeling and stabilization. Recently SigE has been shown to interact with PhoP to activate a subset of genes in conditions of acidic pH. The complex structure of its regulatory network has been suggested to result in a bistable switch leading to the development of heterogeneous bacterial populations. This hypothesis has been recently reinforced by the finding of its involvement in the development of persister cells able to survive to the killing activity of several drugs.
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Affiliation(s)
- Riccardo Manganelli
- Department of Molecular Medicine, University of Padova, Padova, Italy
- *Correspondence: Riccardo Manganelli,
| | | | - Greta Segafreddo
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Francesca Boldrin
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Davide Sorze
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Marta Conflitti
- Department of Molecular Medicine, University of Padova, Padova, Italy
| | - Agnese Serafini
- Department of Molecular Medicine, University of Padova, Padova, Italy
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Cioetto-Mazzabò L, Boldrin F, Beauvineau C, Speth M, Marina A, Namouchi A, Segafreddo G, Cimino M, Favre-Rochex S, Balasingham S, Trastoy B, Munier-Lehmann H, Griffiths G, Gicquel B, Guerin M, Manganelli R, Alonso-Rodríguez N. SigH stress response mediates killing of Mycobacterium tuberculosis by activating nitronaphthofuran prodrugs via induction of Mrx2 expression. Nucleic Acids Res 2022; 51:144-165. [PMID: 36546765 PMCID: PMC9841431 DOI: 10.1093/nar/gkac1173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/17/2022] [Accepted: 12/02/2022] [Indexed: 12/24/2022] Open
Abstract
The emergence of drug-resistant Mycobacterium tuberculosis strains highlights the need to discover anti-tuberculosis drugs with novel mechanisms of action. Here we discovered a mycobactericidal strategy based on the prodrug activation of selected chemical derivatives classified as nitronaphthofurans (nNFs) mediated by the coordinated action of the sigH and mrx2 genes. The transcription factor SigH is a key regulator of an extensive transcriptional network that responds to oxidative, nitrosative, and heat stresses in M. tuberculosis. The nNF action induced the SigH stress response which in turn induced the mrx2 overexpression. The nitroreductase Mrx2 was found to activate nNF prodrugs, killing replicating, non-replicating and intracellular forms of M. tuberculosis. Analysis of SigH DNA sequences obtained from spontaneous nNF-resistant M. tuberculosis mutants suggests disruption of SigH binding to the mrx2 promoter site and/or RNA polymerase core, likely promoting the observed loss of transcriptional control over Mrx2. Mutations found in mrx2 lead to structural defects in the thioredoxin fold of the Mrx2 protein, significantly impairing the activity of the Mrx2 enzyme against nNFs. Altogether, our work brings out the SigH/Mrx2 stress response pathway as a promising target for future drug discovery programs.
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Affiliation(s)
| | | | - Claire Beauvineau
- Chemical Library Institut Curie/CNRS, CNRS UMR9187, INSERM U1196 and CNRS UMR3666, INSERM U1193, Université Paris-Saclay, Orsay 91405, France
| | - Martin Speth
- Department Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo 0371, Norway
| | - Alberto Marina
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Derio 48160 Spain
| | - Amine Namouchi
- Génétique Mycobactérienne, Institute Pasteur, Paris 75015, France,Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, Oslo 0371, Norway
| | - Greta Segafreddo
- Department of Molecular Medicine, University of Padova, Padova 35122, Italy
| | - Mena Cimino
- Génétique Mycobactérienne, Institute Pasteur, Paris 75015, France
| | | | | | - Beatriz Trastoy
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Derio 48160 Spain,Structural Glycobiology Laboratory, Biocruces Bizkaia Health Research Institute, Cruces University Hospital, Bizkaia 48903, Spain
| | - Hélène Munier-Lehmann
- Département de Biologie Structurale et Chimie, Institut Pasteur, CNRS UMR3523, Université de Paris, Paris 75015, France
| | - Gareth Griffiths
- Department Biosciences, Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo 0371, Norway
| | - Brigitte Gicquel
- Génétique Mycobactérienne, Institute Pasteur, Paris 75015, France,Department of Tuberculosis Control and Prevention, Shenzhen Nanshan Centre for Chronic Disease Control, Shenzhen 518054, China
| | - Marcelo E Guerin
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Bizkaia Technology Park, Derio 48160 Spain,Structural Glycobiology Laboratory, Biocruces Bizkaia Health Research Institute, Cruces University Hospital, Bizkaia 48903, Spain,IKERBASQUE, Basque Foundation for Science, Bilbao 48009, Spain
| | - Riccardo Manganelli
- Correspondence may also be addressed to Riccardo Manganelli. Tel: +39 049 827 2366; Fax: +39 049 827 2355;
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