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Guiza Beltran D, Wan T, Zhang L. WhiB-like proteins: Diversity of structure, function and mechanism. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119787. [PMID: 38879133 DOI: 10.1016/j.bbamcr.2024.119787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/20/2024] [Accepted: 06/11/2024] [Indexed: 06/22/2024]
Abstract
The WhiB-Like (Wbl) proteins are a large family of iron-sulfur (Fe-S) cluster-containing transcription factors exclusively found in the phylum Actinobacteria, including the notable genera like Mycobacteria, Streptomycetes and Corynebacteria. These proteins play pivotal roles in diverse biological processes, such as cell development, redox stress response and antibiotic resistance. Members of the Wbl family exhibit remarkable diversity in their sequences, structures and functions, attracting great attention since their first discovery. This review highlights the most recent breakthroughs in understanding the structural and mechanistic aspects of Wbl-dependent transcriptional regulation.
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Affiliation(s)
- Daisy Guiza Beltran
- Department of Biochemistry, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA
| | - Tao Wan
- Department of Biochemistry, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA
| | - LiMei Zhang
- Department of Biochemistry, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA; Redox Biology Center, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA; Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, N138 Beadle Center, 1901 Vine Street, Lincoln, NE 68588, USA.
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Gerges E, Rodríguez-Ordoñez MDP, Durand N, Herrmann JL, Crémazy F. Lsr2, a pleiotropic regulator at the core of the infectious strategy of Mycobacterium abscessus. Microbiol Spectr 2024; 12:e0352823. [PMID: 38353553 PMCID: PMC10913753 DOI: 10.1128/spectrum.03528-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 01/22/2024] [Indexed: 03/06/2024] Open
Abstract
Mycobacterium abscessus is a non-tuberculous mycobacterium, causing lung infections in cystic fibrosis patients. During pulmonary infection, M. abscessus switches from smooth (Mabs-S) to rough (Mabs-R) morphotypes, the latter being hyper-virulent. Previously, we isolated the lsr2 gene as differentially expressed during S-to-R transition. lsr2 encodes a pleiotropic transcription factor that falls under the superfamily of nucleoid-associated proteins. Here, we used two functional genomic methods, RNA-seq and chromatin immunoprecipitation-sequencing (ChIP-seq), to elucidate the molecular role of Lsr2 in the pathobiology of M. abscessus. Transcriptomic analysis shows that Lsr2 differentially regulates gene expression across both morphotypes, most of which are involved in several key cellular processes of M. abscessus, including host adaptation and antibiotic resistance. These results were confirmed through quantitative real-time PCR, as well as by minimum inhibitory concentration tests and infection tests on macrophages in the presence of antibiotics. ChIP-seq analysis revealed that Lsr2 extensively binds the M. abscessus genome at AT-rich sequences and appears to form long domains that participate in the repression of its target genes. Unexpectedly, the genomic distribution of Lsr2 revealed no distinctions between Mabs-S and Mabs-R, implying more intricate mechanisms at play for achieving target selectivity.IMPORTANCELsr2 is a crucial transcription factor and chromosome organizer involved in intracellular growth and virulence in the smooth and rough morphotypes of Mycobacterium abscessus. Using RNA-seq and chromatin immunoprecipitation-sequencing (ChIP-seq), we investigated the molecular role of Lsr2 in gene expression regulation along with its distribution on M. abscessus genome. Our study demonstrates the pleiotropic regulatory role of Lsr2, regulating the expression of many genes coordinating essential cellular and molecular processes in both morphotypes. In addition, we have elucidated the role of Lsr2 in antibiotic resistance both in vitro and in vivo, where lsr2 mutant strains display heightened sensitivity to antibiotics. Through ChIP-seq, we reported the widespread distribution of Lsr2 on M. abscessus genome, revealing a direct repressive effect due to its extensive binding on promoters or coding sequences of its targets. This study unveils the significant regulatory role of Lsr2, intricately intertwined with its function in shaping the organization of the M. abscessus genome.
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Affiliation(s)
- Elias Gerges
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
| | - María del Pilar Rodríguez-Ordoñez
- Université Paris-Saclay, Université d’Evry, Laboratoire Européen de Recherche pour la Polyarthrite rhumatoïde-Genhotel, Evry, France
| | - Nicolas Durand
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
| | - Jean-Louis Herrmann
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
- APHP, GHU Paris-Saclay, Hôpital Raymond Poincaré, Service de Microbiologie, Garches, France
| | - Frédéric Crémazy
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
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Wan T, Horová M, Khetrapal V, Li S, Jones C, Schacht A, Sun X, Zhang L. Structural basis of DNA binding by the WhiB-like transcription factor WhiB3 in Mycobacterium tuberculosis. J Biol Chem 2023; 299:104777. [PMID: 37142222 PMCID: PMC10245118 DOI: 10.1016/j.jbc.2023.104777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 04/23/2023] [Accepted: 04/25/2023] [Indexed: 05/06/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb) WhiB3 is an iron-sulfur cluster-containing transcription factor belonging to a subclass of the WhiB-Like (Wbl) family that is widely distributed in the phylum Actinobacteria. WhiB3 plays a crucial role in the survival and pathogenesis of Mtb. It binds to the conserved region 4 of the principal sigma factor (σA4) in the RNA polymerase holoenzyme to regulate gene expression like other known Wbl proteins in Mtb. However, the structural basis of how WhiB3 coordinates with σA4 to bind DNA and regulate transcription is unclear. Here we determined crystal structures of the WhiB3:σA4 complex without and with DNA at 1.5 Å and 2.45 Å, respectively, to elucidate how WhiB3 interacts with DNA to regulate gene expression. These structures reveal that the WhiB3:σA4 complex shares a molecular interface similar to other structurally characterized Wbl proteins and also possesses a subclass-specific Arg-rich DNA-binding motif. We demonstrate that this newly defined Arg-rich motif is required for WhiB3 binding to DNA in vitro and transcriptional regulation in Mycobacterium smegmatis. Together, our study provides empirical evidence of how WhiB3 regulates gene expression in Mtb by partnering with σA4 and engaging with DNA via the subclass-specific structural motif, distinct from the modes of DNA interaction by WhiB1 and WhiB7.
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Affiliation(s)
- Tao Wan
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Magdaléna Horová
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Vimmy Khetrapal
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Shanren Li
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Camden Jones
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Andrew Schacht
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - Xinghui Sun
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA
| | - LiMei Zhang
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska, USA; Redox Biology Center, University of Nebraska-Lincoln, Lincoln, Nebraska, USA; Nebraska Center for Integrated Biomolecular Communication, University of Nebraska-Lincoln, Lincoln, Nebraska, USA.
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4
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Bo H, Moure UAE, Yang Y, Pan J, Li L, Wang M, Ke X, Cui H. Mycobacterium tuberculosis-macrophage interaction: Molecular updates. Front Cell Infect Microbiol 2023; 13:1062963. [PMID: 36936766 PMCID: PMC10020944 DOI: 10.3389/fcimb.2023.1062963] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 02/13/2023] [Indexed: 03/06/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of Tuberculosis (TB), remains a pathogen of great interest on a global scale. This airborne pathogen affects the lungs, where it interacts with macrophages. Acidic pH, oxidative and nitrosative stressors, and food restrictions make the macrophage's internal milieu unfriendly to foreign bodies. Mtb subverts the host immune system and causes infection due to its genetic arsenal and secreted effector proteins. In vivo and in vitro research have examined Mtb-host macrophage interaction. This interaction is a crucial stage in Mtb infection because lung macrophages are the first immune cells Mtb encounters in the host. This review summarizes Mtb effectors that interact with macrophages. It also examines how macrophages control and eliminate Mtb and how Mtb manipulates macrophage defense mechanisms for its own survival. Understanding these mechanisms is crucial for TB prevention, diagnosis, and treatment.
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Affiliation(s)
- Haotian Bo
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Ulrich Aymard Ekomi Moure
- The Ninth People's Hospital of Chongqing, Affiliated Hospital of Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
| | - Yuanmiao Yang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Jun Pan
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
| | - Li Li
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
| | - Miao Wang
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
| | - Xiaoxue Ke
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
- *Correspondence: Hongjuan Cui, ; Xiaoxue Ke,
| | - Hongjuan Cui
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, China
- Cancer Center, Medical Research Institute, Southwest University, Chongqing, China
- Jinfeng Laboratory, Chongqing, China
- *Correspondence: Hongjuan Cui, ; Xiaoxue Ke,
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Rosa TLSA, Marques MAM, DeBoard Z, Hutchins K, Silva CAA, Montague CR, Yuan T, Amaral JJ, Atella GC, Rosa PS, Mattos KA, VanderVen BC, Lahiri R, Sampson NS, Brennan PJ, Belisle JT, Pessolani MCV, Berrêdo-Pinho M. Reductive Power Generated by Mycobacterium leprae Through Cholesterol Oxidation Contributes to Lipid and ATP Synthesis. Front Cell Infect Microbiol 2021; 11:709972. [PMID: 34395315 PMCID: PMC8355898 DOI: 10.3389/fcimb.2021.709972] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/13/2021] [Indexed: 12/21/2022] Open
Abstract
Upon infection, Mycobacterium leprae, an obligate intracellular bacillus, induces accumulation of cholesterol-enriched lipid droplets (LDs) in Schwann cells (SCs). LDs are promptly recruited to M. leprae-containing phagosomes, and inhibition of this process decreases bacterial survival, suggesting that LD recruitment constitutes a mechanism by which host-derived lipids are delivered to intracellular M. leprae. We previously demonstrated that M. leprae has preserved only the capacity to oxidize cholesterol to cholestenone, the first step of the normal cholesterol catabolic pathway. In this study we investigated the biochemical relevance of cholesterol oxidation on bacterial pathogenesis in SCs. Firstly, we showed that M. leprae increases the uptake of LDL-cholesterol by infected SCs. Moreover, fluorescence microscopy analysis revealed a close association between M. leprae and the internalized LDL-cholesterol within the host cell. By using Mycobacterium smegmatis mutant strains complemented with M. leprae genes, we demonstrated that ml1942 coding for 3β-hydroxysteroid dehydrogenase (3β-HSD), but not ml0389 originally annotated as cholesterol oxidase (ChoD), was responsible for the cholesterol oxidation activity detected in M. leprae. The 3β-HSD activity generates the electron donors NADH and NADPH that, respectively, fuel the M. leprae respiratory chain and provide reductive power for the biosynthesis of the dominant bacterial cell wall lipids phthiocerol dimycocerosate (PDIM) and phenolic glycolipid (PGL)-I. Inhibition of M. leprae 3β-HSD activity with the 17β-[N-(2,5-di-t-butylphenyl)carbamoyl]-6-azaandrost-4-en-3one (compound 1), decreased bacterial intracellular survival in SCs. In conclusion, our findings confirm the accumulation of cholesterol in infected SCs and its potential delivery to the intracellular bacterium. Furthermore, we provide strong evidence that cholesterol oxidation is an essential catabolic pathway for M. leprae pathogenicity and point to 3β-HSD as a prime drug target that may be used in combination with current multidrug regimens to shorten leprosy treatment and ameliorate nerve damage.
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Affiliation(s)
- Thabatta L S A Rosa
- Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Maria Angela M Marques
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Zachary DeBoard
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Kelly Hutchins
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Carlos Adriano A Silva
- Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Christine R Montague
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY, United States
| | - Tianao Yuan
- Department of Chemistry, Stony Brook University, Stony Brook, NY, United States
| | - Julio J Amaral
- Laboratório de Química Biológica, Diretoria de Metrologia Aplicada às Ciências da Vida, Instituto Nacional de Metrologia, Qualidade e Tecnologia, Rio de Janeiro, Brazil
| | - Georgia C Atella
- Laboratório de Bioquímica de Lipídeos e Lipoproteínas, Instituto de Bioquímica Médica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Patrícia S Rosa
- Divisão de Pesquisa e Ensino, Instituto Lauro de Souza Lima, Bauru, Brazil
| | - Katherine A Mattos
- Departmento de Controle de Qualidade, Instituto de Tecnologia em Imunobiológicos, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Brian C VanderVen
- Department of Microbiology and Immunology, Cornell University, Ithaca, NY, United States
| | - Ramanuj Lahiri
- Department of Health and Human Services, Health Resources and Services Administration, Healthcare Systems Bureau, National Hansen's Disease Programs, Baton Rouge, LA, United States
| | - Nicole S Sampson
- Department of Chemistry, Stony Brook University, Stony Brook, NY, United States
| | - Patrick J Brennan
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - John T Belisle
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Maria Cristina V Pessolani
- Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Marcia Berrêdo-Pinho
- Laboratório de Microbiologia Celular, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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Ma H, Liu WB, Zhang XP, Hu HQ, Gu SD, Yuan H, Ye BC. GlnR-mediated regulation of KstR controls cholesterol catabolism in Mycobacterium smegmatis. Biotechnol Appl Biochem 2021; 69:1209-1216. [PMID: 34008246 DOI: 10.1002/bab.2197] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 05/12/2021] [Indexed: 11/10/2022]
Abstract
Tuberculosis, caused by mycobacteria, continues to pose a substantial public health threat. Mycobacteria typically use cholesterol from the membranes of host macrophages as a carbon and energy source. Most genes that control cholesterol degradation are regulated by KstR, which is highly conserved in Mycobacterium tuberculosis and Mycobacterium smegmatis. Through bioinformatic analysis, we found a typical global nitrogen regulator (GlnR)-binding motif (CCGAC-AACAGT-GACAC) in the promoter region of kstR of M. smegmatis, and we determined its binding activity in vitro using electrophoretic mobility shift assays. Using RT-qPCR, we found that nine genes involved in side-chain or sterol-ring oxidation were upregulated in a ΔglnR M. smegmatis strain compared to the WT strain and glnR-complemented strains under nitrogen limitation. ATP assays in macrophages revealed that coordinated GlnR-KstR regulation significantly reduced the viability of M. smegmatis in macrophages. Thus, we found that various genes involved in cholesterol catabolism are regulated by GlnR via KstR in response to environmental nitrogen, and that they further affect the invasive ability of M. smegmatis. These findings revealed a novel regulatory mechanism of cholesterol catabolism, which may be useful in the development of new strategies for controlling tuberculosis.
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Affiliation(s)
- Heng Ma
- School of Chemistry and Chemical Engineering, Shihezi University, Xinjiang, China
| | - Wei-Bing Liu
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Xiao-Peng Zhang
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Hao-Qi Hu
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Sheng-Di Gu
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Hao Yuan
- Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Bang-Ce Ye
- School of Chemistry and Chemical Engineering, Shihezi University, Xinjiang, China.,Lab of Biosystems and Microanalysis, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China.,Institute of Engineering Biology and Health, Collaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals, College of Pharmaceutical Sciences, Zhejiang University of Technology, Hangzhou, Zhejiang, China
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Role of LmeA, a Mycobacterial Periplasmic Protein, in Maintaining the Mannosyltransferase MptA and Its Product Lipomannan under Stress. mSphere 2020; 5:5/6/e01039-20. [PMID: 33148829 PMCID: PMC7643837 DOI: 10.1128/msphere.01039-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Mycobacteria differentially regulate the cellular amounts of lipoglycans in response to environmental changes, but the molecular mechanisms of this regulation remain unknown. Here, we demonstrate that cellular lipoarabinomannan (LAM) levels rapidly decline under two stress conditions, stationary growth phase and nutrient starvation, while the levels of another related lipoglycan, lipomannan (LM), stay relatively constant. The persistence of LM under stress correlated with the maintenance of two key mannosyltransferases, MptA and MptC, in the LM biosynthetic pathway. We further showed that the stress exposures lead to the upregulation of lmeA gene expression and that the periplasmic protein LmeA plays a key role in maintaining the enzyme MptA and its product LM under stress conditions. These findings reveal new aspects of how lipoglycan biosynthesis is regulated under stress conditions in mycobacteria. The mycobacterial cell envelope has a diderm structure, composed of an outer mycomembrane, an arabinogalactan-peptidoglycan cell wall, a periplasm, and an inner membrane. Lipomannan (LM) and lipoarabinomannan (LAM) are structural and immunomodulatory components of this cell envelope. LM/LAM biosynthesis involves a number of mannosyltransferases and acyltransferases, and MptA is an α1,6-mannosyltransferase involved in the final extension of the mannan chain. Recently, we reported the periplasmic protein LmeA being involved in the maturation of the mannan backbone in Mycobacterium smegmatis. Here, we examined the role of LmeA under stress conditions. We found that lmeA transcription was upregulated under two stress conditions: stationary growth phase and nutrient starvation. Under both conditions, LAM was decreased, but LM was relatively stable, suggesting that maintaining the cellular level of LM under stress is important. Surprisingly, the protein levels of MptA were decreased in an lmeA deletion (ΔlmeA) mutant under both stress conditions. The transcript levels of mptA in the ΔlmeA mutant were similar to or even higher than those in the wild type, indicating that the decrease of MptA protein was a posttranscriptional event. The ΔlmeA mutant was unable to maintain the cellular level of LM under stress, consistent with the decrease in MptA. Even during active growth, overexpression of LmeA led the cells to produce more LM and become more resistant to several antibiotics. Altogether, our study reveals the roles of LmeA in the homeostasis of the MptA mannosyltransferase, particularly under stress conditions, ensuring the stable expression of LM and the maintenance of cell envelope integrity. IMPORTANCE Mycobacteria differentially regulate the cellular amounts of lipoglycans in response to environmental changes, but the molecular mechanisms of this regulation remain unknown. Here, we demonstrate that cellular lipoarabinomannan (LAM) levels rapidly decline under two stress conditions, stationary growth phase and nutrient starvation, while the levels of another related lipoglycan, lipomannan (LM), stay relatively constant. The persistence of LM under stress correlated with the maintenance of two key mannosyltransferases, MptA and MptC, in the LM biosynthetic pathway. We further showed that the stress exposures lead to the upregulation of lmeA gene expression and that the periplasmic protein LmeA plays a key role in maintaining the enzyme MptA and its product LM under stress conditions. These findings reveal new aspects of how lipoglycan biosynthesis is regulated under stress conditions in mycobacteria.
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Sousa EH, Carepo MS, Moura JJ. Nitrate-nitrite fate and oxygen sensing in dormant Mycobacterium tuberculosis: A bioinorganic approach highlighting the importance of transition metals. Coord Chem Rev 2020. [DOI: 10.1016/j.ccr.2020.213476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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Mahatha AC, Mal S, Majumder D, Saha S, Ghosh A, Basu J, Kundu M. RegX3 Activates whiB3 Under Acid Stress and Subverts Lysosomal Trafficking of Mycobacterium tuberculosis in a WhiB3-Dependent Manner. Front Microbiol 2020; 11:572433. [PMID: 33042081 PMCID: PMC7525159 DOI: 10.3389/fmicb.2020.572433] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 08/10/2020] [Indexed: 11/17/2022] Open
Abstract
Two-component systems (TCSs) are central to the ability of Mycobacterium tuberculosis to respond to stress. One such paired TCS is SenX3-RegX3, which responds to phosphate starvation. Here we show that RegX3 is required for M. tuberculosis to withstand low pH, one of the challenges encountered by the bacterium in the host environment, and that RegX3 activates the cytosolic redox sensor WhiB3 to launch an appropriate response to acid stress. We show that the whiB3 promoter of M. tuberculosis harbors a RegX3 binding motif. Electrophoretic mobility shift assays (EMSAs) show that phosphorylated RegX3 (RegX3-P) (but not its unphosphorylated counterpart) binds to this motif, whereas a DNA binding mutant, RegX3 (K204A) fails to do so. Mutation of the putative RegX3 binding motif on the whiB3 promoter, abrogates the binding of RegX3-P. The significance of this binding is established by demonstrating that the expression of whiB3 is significantly attenuated under phosphate starvation or under acid stress in the regX3-inactivated mutant, ΔregX3. Green fluorescent protein (GFP)-based reporter assays further confirm the requirement of RegX3 for the activation of the whiB3 promoter. The compromised survival of ΔregX3 under acid stress and its increased trafficking to the lysosomal compartment are reversed upon complementation with either regX3 or whiB3, suggesting that RegX3 exerts its effects in a WhiB3-dependent manner. Finally, using an in vitro granuloma model, we show that granuloma formation is compromised in the absence of regX3, but restored upon complementation with either regX3 or whiB3. Our findings provide insight into an important role of RegX3 in the network that regulates the survival of M. tuberculosis under acid stress similar to that encountered in its intracellular niche. Our results argue strongly in favor of a role of the RegX3-WhiB3 axis in establishment of M. tuberculosis infection.
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Affiliation(s)
| | - Soumya Mal
- Department of Chemistry, Bose Institute, Kolkata, India
| | | | - Sudipto Saha
- Division of Bioinformatics, Bose Institute, Kolkata, India
| | - Abhirupa Ghosh
- Division of Bioinformatics, Bose Institute, Kolkata, India
| | - Joyoti Basu
- Department of Chemistry, Bose Institute, Kolkata, India
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10
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Discovery of ANTAR-RNAs and their Mechanism of Action in Mycobacteria. J Mol Biol 2020; 432:4032-4048. [PMID: 32422150 DOI: 10.1016/j.jmb.2020.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/07/2020] [Accepted: 05/07/2020] [Indexed: 02/07/2023]
Abstract
Non-coding RNAs play pivotal roles in bacterial signaling. However, RNAs from certain phyla (specially high-GC actinobacteria) still remain elusive. Here, by re-engineering the existing genome-wide search approach, we discover a family of structurally conserved RNAs that are present ubiquitously across actinobacteria, including mycobacteria. In vitro analysis shows that RNAs belonging to this family bind response-regulator proteins that contain the widely prevalent ANTAR domain. The Mycobacterium tuberculosis ANTAR protein gets phosphorylated by a histidine kinase and interacts with RNA only in its phosphorylated state. These newly identified RNAs reside only in certain transcripts and typically overlap with the ribosome-binding site, regulating translation of these transcripts. In this way, the RNAs directly link signaling pathways to translational control, thus expanding the mechanistic tool kit available for ANTAR-based control of gene expression. In mycobacteria, we find that RNAs targeted by ANTAR proteins majorly encode enzymes of lipid metabolism and associated redox pathways. This now allows us to identify the key genes that mediate ANTAR-dependent control of lipid metabolism. Our study establishes the identity and wide prevalence of ANTAR-target RNAs in mycobacteria, bringing RNA-mediated regulation in these bacteria to the center stage.
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