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Ensinck D, Gerhardt ECM, Rollan L, Huergo LF, Gramajo H, Diacovich L. The PII protein interacts with the Amt ammonium transport and modulates nitrate/nitrite assimilation in mycobacteria. Front Microbiol 2024; 15:1366111. [PMID: 38591044 PMCID: PMC11001197 DOI: 10.3389/fmicb.2024.1366111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/04/2024] [Indexed: 04/10/2024] Open
Abstract
PII proteins are signal transduction proteins that belong to a widely distributed family of proteins involved in the modulation of different metabolisms in bacteria. These proteins are homotrimers carrying a flexible loop, named T-loop, which changes its conformation due to the recognition of diverse key metabolites, ADP, ATP, and 2-oxoglutarate. PII proteins interact with different partners to primarily regulate a set of nitrogen pathways. In some organisms, PII proteins can also control carbon metabolism by interacting with the biotin carboxyl carrier protein (BCCP), a key component of the acetyl-CoA carboxylase (ACC) enzyme complex, inhibiting its activity with the consequent reduction of fatty acid biosynthesis. Most bacteria contain at least two PII proteins, named GlnB and GlnK, with different regulatory roles. In mycobacteria, only one PII protein was identified, and the three-dimensional structure was solved, however, its physiological role is unknown. In this study we purified the Mycobacterium tuberculosis (M. tb) PII protein, named GlnB, and showed that it weakly interacts with the AccA3 protein, the α subunit shared by the three different, and essential, Acyl-CoA carboxylase complexes (ACCase 4, 5, and 6) present in M. tb. A M. smegmatis deletion mutant, ∆MsPII, exhibited a growth deficiency on nitrate and nitrite as unique nitrogen sources, and accumulated nitrite in the culture supernatant. In addition, M. tb PII protein was able to interact with the C-terminal domain of the ammonium transporter Amt establishing the ancestral role for this PII protein as a GlnK functioning protein.
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Affiliation(s)
- Delfina Ensinck
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Edileusa C. M. Gerhardt
- Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Paraná, Brazil
| | - Lara Rollan
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Luciano F. Huergo
- Setor Litoral, Federal University of Paraná, Universidade Federal do Paraná (UFPR), Matinhos, Paraná, Brazil
- Graduated Program in Sciences-Biochemistry, Universidade Federal do Paraná (UFPR), Curitiba, Paraná, Brazil
| | - Hugo Gramajo
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Lautaro Diacovich
- Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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Xu Y, Ma S, Huang Z, Wang L, Raza SHA, Wang Z. Nitrogen metabolism in mycobacteria: the key genes and targeted antimicrobials. Front Microbiol 2023; 14:1149041. [PMID: 37275154 PMCID: PMC10232911 DOI: 10.3389/fmicb.2023.1149041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 05/05/2023] [Indexed: 06/07/2023] Open
Abstract
Nitrogen metabolism is an important physiological process that affects the survival and virulence of Mycobacterium tuberculosis. M. tuberculosis's utilization of nitrogen in the environment and its adaptation to the harsh environment of acid and low oxygen in macrophages are closely related to nitrogen metabolism. In addition, the dormancy state and drug resistance of M. tuberculosis are closely related to nitrogen metabolism. Although nitrogen metabolism is so important, limited research was performed on nitrogen metabolism as compared with carbon metabolism. M. tuberculosis can use a variety of inorganic or organic nitrogen sources, including ammonium salts, nitrate, glutamine, asparagine, etc. In these metabolic pathways, some enzymes encoded by key genes, such as GlnA1, AnsP2, etc, play important regulatory roles in the pathogenesis of TB. Although various small molecule inhibitors and drugs have been developed for different nitrogen metabolism processes, however, long-term validation is needed before their practical application. Most importantly, with the emergence of multidrug-resistant strains, eradication, and control of M. tuberculosis will still be very challenging.
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Affiliation(s)
- Yufan Xu
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Shiwei Ma
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Zixin Huang
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Longlong Wang
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
| | - Sayed Haidar Abbas Raza
- Guangdong Provincial Key Laboratory of Food Quality and Safety/Nation-Local Joint Engineering Research Center for Machining and Safety of Livestock and Poultry Products, South China Agricultural University, Guangzhou, China
| | - Zhe Wang
- Shanghai Collaborative Innovation Center of Agri-Seeds, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Veterinary Biotechnology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai, China
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Pisu D, Huang L, Grenier JK, Russell DG. Dual RNA-Seq of Mtb-Infected Macrophages In Vivo Reveals Ontologically Distinct Host-Pathogen Interactions. Cell Rep 2021; 30:335-350.e4. [PMID: 31940480 PMCID: PMC7032562 DOI: 10.1016/j.celrep.2019.12.033] [Citation(s) in RCA: 126] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 10/31/2019] [Accepted: 12/10/2019] [Indexed: 12/13/2022] Open
Abstract
Dissecting the in vivo host-pathogen interplay is crucial to understanding the molecular mechanisms governing control or progression of intracellular infections. In this work, we explore the in vivo molecular dynamics of Mtb infection by performing dual RNA-seq on Mycobacterium tuberculosis-infected, ontogenetically distinct macrophage lineages isolated directly from murine lungs. We first define an in vivo signature of 180 genes specifically upregulated by Mtb in mouse lung macrophages, then we uncover a divergent transcriptional response of the bacteria between alveolar macrophages that appear to sustain Mtb growth through increased access to iron and fatty acids and interstitial macrophages that restrict Mtb growth through iron sequestration and higher levels of nitric oxide. We use an enrichment protocol for bacterial transcripts, which enables us to probe Mtb physiology at the host cell level in an in vivo environment, with broader application in understanding the infection dynamics of intracellular pathogens in general. In this study Pisu et al. performed dual RNA-seq on Mycobacterium tuberculosis-infected, ontogenetically distinct macrophage lineages isolated directly from infected murine lungs. The transcriptional response of host and bacteria diverged between alveolar macrophages that sustain Mtb growth and interstitial macrophages that restrict Mtb growth.
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Affiliation(s)
- Davide Pisu
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Lu Huang
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - Jennifer K Grenier
- RNA Sequencing Core, Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - David G Russell
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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Raze D, Segers J, Mille C, Slupek S, Lecher S, Coutte L, Antoine R, Ducrocq L, Rouanet C, Appelmelk BJ, Locht C. Coordinate regulation of virulence and metabolic genes by the transcription factor HbhR in Mycobacterium marinum. Mol Microbiol 2019; 113:52-67. [PMID: 31587365 DOI: 10.1111/mmi.14400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2019] [Indexed: 12/17/2022]
Abstract
The heparin-binding hemagglutinin (HBHA) is a multifunctional protein involved in adherence of Mycobacterium tuberculosis to non-phagocytic cells and in the formation of intracytosolic lipid inclusions. We demonstrate that the expression of hbhA is regulated by a transcriptional repressor, named HbhR, in Mycobacterium marinum. The hbhR gene, located upstream of hbhA, was identified by screening a transposon insertion library and detailed analysis of a mutant overproducing HBHA. HbhR was found to repress both hbhA and hbhR transcription by binding to the promoter regions of both genes. Complementation restored production of HBHA. RNA-seq analyses comparing the mutant and parental strains uncovered 27 genes, including hbhA, that were repressed and 20 genes activated by HbhR. Among the former, the entire locus of genes coding for a type-VII secretion system, including esxA, esxB and pe-ppe paralogs, as well as the gene coding for PspA, present in intracellular lipid vesicles, was identified, as was katG, a gene involved in the sensitivity to isoniazid. The latter category contains genes that play a role in diverse functions, such as metabolism and resistance to oxidative conditions. Thus, HbhR appears to be a master regulator, linking the transcriptional regulation of virulence, metabolic and antibiotic sensitivity genes in M. marinum.
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Affiliation(s)
- Dominique Raze
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Jérôme Segers
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Céline Mille
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Stéphanie Slupek
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Sophie Lecher
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Loïc Coutte
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Rudy Antoine
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Lucie Ducrocq
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Carine Rouanet
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
| | - Ben J Appelmelk
- Molecular Microbiology/Medical Microbiology and Infection Control, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Camille Locht
- CIIL - Center for Infection and Immunity of Lille, Univ. Lille, CNRS, INSERM, Institut Pasteur de Lille, U1019 - UMR 8204, Lille, F-59000, France
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Cho BC, Hardies SC, Jang GI, Hwang CY. Complete genome of streamlined marine actinobacterium Pontimonas salivibrio strain CL-TW6 T adapted to coastal planktonic lifestyle. BMC Genomics 2018; 19:625. [PMID: 30134835 PMCID: PMC6106888 DOI: 10.1186/s12864-018-5019-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 08/14/2018] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Pontimonas salivibrio strain CL-TW6T (=KCCM 90105 = JCM18206) was characterized as the type strain of a new genus within the Actinobacterial family Microbacteriaceae. It was isolated from a coastal marine environment in which members of Microbactericeae have not been previously characterized. RESULTS The genome of P. salivibrio CL-TW6T was a single chromosome of 1,760,810 bp. Genomes of this small size are typically found in bacteria growing slowly in oligotrophic zones and said to be streamlined. Phylogenetic analysis showed it to represent a lineage originating in the Microbacteriaceae radiation occurring before the snowball Earth glaciations, and to have a closer relationship with some streamlined bacteria known through metagenomic data. Several genomic characteristics typical of streamlined bacteria are found: %G + C is lower than non-streamlined members of the phylum; there are a minimal number of rRNA and tRNA genes, fewer paralogs in most gene families, and only two sigma factors; there is a noticeable absence of some nonessential metabolic pathways, including polyketide synthesis and catabolism of some amino acids. There was no indication of any phage genes or plasmids, however, a system of active insertion elements was present. P. salivibrio appears to be unusual in having polyrhamnose-based cell wall oligosaccharides instead of mycolic acid or teichoic acid-based oligosaccharides. Oddly, it conducts sulfate assimilation apparently for sulfating cell wall components, but not for synthesizing amino acids. One gene family it has more of, rather than fewer of, are toxin/antitoxin systems, which are thought to down-regulate growth during nutrient deprivation or other stressful conditions. CONCLUSIONS Because of the relatively small number of paralogs and its relationship to the heavily characterized Mycobacterium tuberculosis, we were able to heavily annotate the genome of P. salivibrio CL-TW6T. Its streamlined status and relationship to streamlined metagenomic constructs makes it an important reference genome for study of the streamlining concept. The final evolutionary trajectory of CL-TW6 T was to adapt to growth in a non-oligotrophic coastal zone. To understand that adaptive process, we give a thorough accounting of gene content, contrasting with both oligotrophic streamlined bacteria and large genome bacteria, and distinguishing between genes derived by vertical and horizontal descent.
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Affiliation(s)
- Byung Cheol Cho
- Microbial Oceanography Laboratory, School of Earth and Environmental Sciences and Research Institute of Oceanography, Seoul National University, Gwanak-gu, Seoul, Republic of Korea
| | - Stephen C. Hardies
- Department of Biochemistry, The University of Texas Health Science Center at San Antonio, San Antonio, TX USA
| | - Gwang Il Jang
- Microbial Oceanography Laboratory, School of Earth and Environmental Sciences and Research Institute of Oceanography, Seoul National University, Gwanak-gu, Seoul, Republic of Korea
- Division of Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
| | - Chung Yeon Hwang
- Division of Life Sciences, Korea Polar Research Institute, Incheon, Republic of Korea
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Luang-In V, Narbad A, Cebeci F, Bennett M, Rossiter JT. Identification of Proteins Possibly Involved in Glucosinolate Metabolism in L. agilis R16 and E. coli VL8. Protein J 2016; 34:135-46. [PMID: 25805049 DOI: 10.1007/s10930-015-9607-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study was aimed to identify sinigrin-induced bacterial proteins potentially involved in the metabolism of glucosinolate in two glucosinolate-metabolising bacteria Lactobacillus agilis R16 and Escherichia coli VL8. Sinigrin (2 mM) was used to induce the proteins in both bacteria under anaerobic incubation for 8 h at 30 °C for L. agilis R16 and 37 °C for E. coli VL8 and the controls without sinigrin were performed. Allyl isothiocyanate and allyl nitrile as two degradation products of sinigrin were detected in sinigrin-induced cultures of L. agilis R16 (27% total products) and E. coli VL8 (38% total products) from a complete sinigrin degradation in 8 h for both bacteria. 2D gel electrophoresis was conducted to identify induced proteins with at least twofold increased abundance. Sinigrin-induced L. agilis R16 and the control produced 1561 and 1543 protein spots, respectively. For E. coli VL8, 1363 spots were detected in sinigrin-induced and 1354 spots in the control. A combination of distinct proteins and upregulated proteins of 32 and 35 spots in L. agilis R16 and E. coli VL8, respectively were detected upon sinigrin induction. Of these, 12 and 16 spots from each bacterium respectively were identified by LC-MS/MS. In both bacteria most of the identified proteins are involved in carbohydrate metabolism, oxidoreduction system and sugar transport while the minority belong to purine metabolism, hydrolysis, and proteolysis. This indicated that sinigrin induction led to the expressions of proteins with similar functions in both bacteria and these proteins may play a role in bacterial glucosinolate metabolism.
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Affiliation(s)
- Vijitra Luang-In
- Natural Antioxidant Research Unit, Department of Biotechnology, Faculty of Technology, Mahasarakham University, Mahasarakham, 44150, Thailand,
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Petridis M, Benjak A, Cook GM. Defining the nitrogen regulated transcriptome of Mycobacterium smegmatis using continuous culture. BMC Genomics 2015; 16:821. [PMID: 26482235 PMCID: PMC4617892 DOI: 10.1186/s12864-015-2051-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 10/06/2015] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Nitrogen is essential for microbial growth and its importance is demonstrated by the complex regulatory systems used to control the transport, assimilation and metabolism of nitrogen. Recent studies are beginning to shed light on how mycobacteria respond to nitrogen limitation and several regulators (e.g., GlnR, PII) have been characterized at a molecular level. However, despite this progress, our knowledge of the transcriptional response of mycobacteria to nitrogen limitation and its regulation is confined to batch culture. METHODS To gain further insight into the response of mycobacteria to nitrogen limitation, we developed a nitrogen-limited chemostat. We compared the transcriptional response of nitrogen-limited cells to carbon-limited cells using RNA-seq analysis in a continuous culture model at a constant growth rate. CONCLUSIONS Our findings revealed significant changes in the expression of 357 genes (208 upregulated, 149 downregulated; >2-fold change, false discovery rate <5 %) in response to nitrogen limitation in continuous culture. The vast majority of the GlnR regulon (68 %) was differentially expressed under nitrogen limitation in continuous culture and approximately 52 % of the 357 genes overlapped with a previously published study investigating the response of M. smegmatis to nitrogen limitation in batch culture, while expression of only 17 % of the genes identified in batch culture were affected in our chemostat model. Moreover, we identified a unique set of 45 genes involved in the uptake and metabolism of nitrogen that were exclusive to our chemostat model. We observed strong downregulation of pathways for amino acid catabolism (i.e., alanine, aspartate, valine, proline and lysine), suggesting preservation of these amino acids for critical cellular function. We found 16 novel transcriptional regulators that were directly or indirectly involved in the global transcriptomic response of M. smegmatis to nitrogen limitation and identified several non-coding RNAs that might be involved in the transcriptional or post-transcriptional regulation of nitrogen-regulated gene expression. RESULTS Using nitrogen-limited continuous culture we identified the nitrogen-responsive transcriptome of M. smegmatis, including a number of small non-coding RNAs implicated in controlling nitrogen-regulated gene expression.
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Affiliation(s)
- Michael Petridis
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, P.O. Box 56, Dunedin, New Zealand. .,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland, 1042, New Zealand.
| | - Andrej Benjak
- Global Health Institute, École Polytechnique Fédérale de Lausanne, Lausanne, 1015, Switzerland.
| | - Gregory M Cook
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, P.O. Box 56, Dunedin, New Zealand. .,Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Private Bag 92019, Auckland, 1042, New Zealand.
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Williams KJ, Jenkins VA, Barton GR, Bryant WA, Krishnan N, Robertson BD. Deciphering the metabolic response of Mycobacterium tuberculosis to nitrogen stress. Mol Microbiol 2015; 97:1142-57. [PMID: 26077160 PMCID: PMC4950008 DOI: 10.1111/mmi.13091] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2014] [Indexed: 12/21/2022]
Abstract
A key component to the success of Mycobacterium tuberculosis as a pathogen is the ability to sense and adapt metabolically to the diverse range of conditions encountered in vivo, such as oxygen tension, environmental pH and nutrient availability. Although nitrogen is an essential nutrient for every organism, little is known about the genes and pathways responsible for nitrogen assimilation in M. tuberculosis. In this study we have used transcriptomics and chromatin immunoprecipitation and high‐throughput sequencing to address this. In response to nitrogen starvation, a total of 185 genes were significantly differentially expressed (96 up‐regulated and 89 down regulated; 5% genome) highlighting several significant areas of metabolic change during nitrogen limitation such as nitrate/nitrite metabolism, aspartate metabolism and changes in cell wall biosynthesis. We identify GlnR as a regulator involved in the nitrogen response, controlling the expression of at least 33 genes in response to nitrogen limitation. We identify a consensus GlnR binding site and relate its location to known transcriptional start sites. We also show that the GlnR response regulator plays a very different role in M. tuberculosis to that in non‐pathogenic mycobacteria, controlling genes involved in nitric oxide detoxification and intracellular survival instead of genes involved in nitrogen scavenging.
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Affiliation(s)
- Kerstin J Williams
- MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Victoria A Jenkins
- MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Geraint R Barton
- Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London, SW7 2AZ, UK
| | - William A Bryant
- Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London, SW7 2AZ, UK
| | - Nitya Krishnan
- MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College London, London, SW7 2AZ, UK
| | - Brian D Robertson
- MRC Centre for Molecular Bacteriology and Infection, Department of Medicine, Imperial College London, London, SW7 2AZ, UK.,Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London, SW7 2AZ, UK
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Abstract
Several major pathogens, including Mycobacterium tuberculosis, parasitize host cells and exploit host-derived nutrients to sustain their own metabolism. Although the carbon sources that are used by M. tuberculosis have been extensively studied, the mechanisms by which mycobacteria capture and metabolize nitrogen, which is another essential constituent of biomolecules, have only recently been revisited. In this Progress article, we discuss central nitrogen metabolism in M. tuberculosis, the mechanisms that are used by this pathogen to obtain nitrogen from its host and the potential role of nitrogen capture and metabolism in virulence.
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Jain S, Mandal RS, Anand S, Maiti S, Ramachandran S. Probing the amino acids critical for protein oligomerisation and protein-nucleotide interaction in Mycobacterium tuberculosis PII protein through integration of computational and experimental approaches. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2736-49. [PMID: 24129075 DOI: 10.1016/j.bbapap.2013.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 10/05/2013] [Accepted: 10/07/2013] [Indexed: 11/26/2022]
Abstract
We investigated the interacting amino acids critical for the stability and ATP binding of Mycobacterium tuberculosis PII protein through a series of site specific mutagenesis experiments. We assessed the effect of mutants using glutaraldehyde crosslinking and size exclusion chromatography and isothermal titration calorimetry. Mutations in the amino acid pair R60-E62 affecting central electrostatic interaction resulted in insoluble proteins. Multiple sequence alignment of PII orthologs displayed a conserved pattern of charged residues at these positions. Mutation of amino acid D97 to a neutral residue was tolerated whereas positive charge was not acceptable. Mutation of R107 alone had no effect on trimer formation. However, the combination of neutral residues both at positions 97 and 107 was not acceptable even with the pair at 60-62 intact. Reversal of charge polarity could partially restore the interaction. The residues including K90, R101 and R103 with potential to form H-bonds to ATP are conserved throughout across numerous orthologs of PII but when mutated to Alanine, they did not show significant differences in the total free energy change of the interaction as examined through isothermal titration calorimetry. The ATP binding pattern showed anti-cooperativity using three-site binding model. We observed compensatory effect in enthalpy and entropy changes and these may represent structural adjustments to accommodate ATP in the cavity even in absence of some interactions to perform the requisite function. In this respect these small differences between the PII orthologs may have evolved to suite species specific physiological niches.
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Affiliation(s)
- Sriyans Jain
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, New Delhi 110 007, India
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Jenkins VA, Barton GR, Robertson BD, Williams KJ. Genome wide analysis of the complete GlnR nitrogen-response regulon in Mycobacterium smegmatis. BMC Genomics 2013; 14:301. [PMID: 23642041 PMCID: PMC3662644 DOI: 10.1186/1471-2164-14-301] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 04/29/2013] [Indexed: 11/24/2022] Open
Abstract
Background Nitrogen is an essential element for bacterial growth and an important component of biological macromolecules. Consequently, responding to nitrogen limitation is critical for bacterial survival and involves the interplay of signalling pathways and transcriptional regulation of nitrogen assimilation and scavenging genes. In the soil dwelling saprophyte Mycobacterium smegmatis the OmpR-type response regulator GlnR is thought to mediate the transcriptomic response to nitrogen limitation. However, to date only ten genes have been shown to be in the GlnR regulon, a vastly reduced number compared to other organisms. Results We investigated the role of GlnR in the nitrogen limitation response and determined the entire GlnR regulon, by combining expression profiling of M. smegmatis wild type and glnR deletion mutant, with GlnR-specific chromatin immunoprecipitation and high throughput sequencing. We identify 53 GlnR binding sites during nitrogen limitation that control the expression of over 100 genes, demonstrating that GlnR is the regulator controlling the assimilation and utilisation of nitrogen. We also determine a consensus GlnR binding motif and identify key residues within the motif that are required for specific GlnR binding. Conclusions We have demonstrated that GlnR is the global nitrogen response regulator in M. smegmatis, directly regulating the expression of more than 100 genes. GlnR controls key nitrogen stress survival processes including primary nitrogen metabolism pathways, the ability to utilise nitrate and urea as alternative nitrogen sources, and the potential to use cellular components to provide a source of ammonium. These studies further our understanding of how mycobacteria survive nutrient limiting conditions.
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Affiliation(s)
- Victoria A Jenkins
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, South Kensington, London SW7 2AZ, UK
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