1
|
Rs N, Sinha SK, Batra S, Regatti PR, Syal K. Promoter characterization of relZ-bifunctional (pp)pGpp synthetase in mycobacteria. Genes Cells 2024. [PMID: 38923083 DOI: 10.1111/gtc.13135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/30/2024] [Accepted: 06/03/2024] [Indexed: 06/28/2024]
Abstract
The second messenger guanosine 3',5'-bis(diphosphate)/guanosine tetraphosphate (ppGpp) and guanosine 3'-diphosphate 5'-triphosphate/guanosine pentaphosphate (pppGpp) ((p)ppGpp) has been shown to be crucial for the survival of mycobacteria under hostile conditions. Unexpectedly, deletion of primary (p)ppGpp synthetase-Rel did not completely diminish (p)ppGpp levels leading to the discovery of novel bifunctional enzyme-RelZ, which displayed guanosine 5'-monophosphate,3'-diphosphate (pGpp), ppGpp, and pppGpp ((pp)pGpp) synthesis and RNAseHII activity. What conditions does it express itself under, and does it work in concert with Rel? The regulation of its transcription and whether the Rel enzyme plays a role in such regulation remain unclear. In this article, we have studied relZ promoter and compared its activity with rel promoter in different growth conditions. We observed that the promoter activity of relZ was constitutive; it is weaker than rel promoter, lies within 200 bp upstream of translation-start site, and it increased under carbon starvation. Furthermore, the promoter activity of relZ was compromised in the rel-knockout strain in the stationary phase. Our study unveils the dynamic regulation of relZ promoter activity by SigA and SigB sigma factors in different growth phases in mycobacteria. Importantly, elucidating the regulatory network of RelZ would enable the development of the targeted interventions for treating mycobacterial infections.
Collapse
Affiliation(s)
- Neethu Rs
- Genetics and Molecular Microbiology Laboratory, Department of Biological Sciences, Institute of Eminence, Birla Institute of Technology and Sciences-Pilani, Hyderabad, Telangana, India
| | - Shubham Kumar Sinha
- Genetics and Molecular Microbiology Laboratory, Department of Biological Sciences, Institute of Eminence, Birla Institute of Technology and Sciences-Pilani, Hyderabad, Telangana, India
| | - Sakshi Batra
- Genetics and Molecular Microbiology Laboratory, Department of Biological Sciences, Institute of Eminence, Birla Institute of Technology and Sciences-Pilani, Hyderabad, Telangana, India
- Department of Pulmonary Medicine, Malla Reddy Institute of Medical Sciences, Hyderabad, Telangana, India
| | - Pavan Reddy Regatti
- Genetics and Molecular Microbiology Laboratory, Department of Biological Sciences, Institute of Eminence, Birla Institute of Technology and Sciences-Pilani, Hyderabad, Telangana, India
| | - Kirtimaan Syal
- Genetics and Molecular Microbiology Laboratory, Department of Biological Sciences, Institute of Eminence, Birla Institute of Technology and Sciences-Pilani, Hyderabad, Telangana, India
| |
Collapse
|
2
|
Santoshi M, Tare P, Nagaraja V. Nucleoid-associated proteins of mycobacteria come with a distinctive flavor. Mol Microbiol 2024. [PMID: 38922783 DOI: 10.1111/mmi.15287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Revised: 05/31/2024] [Accepted: 06/05/2024] [Indexed: 06/28/2024]
Abstract
In every bacterium, nucleoid-associated proteins (NAPs) play crucial roles in chromosome organization, replication, repair, gene expression, and other DNA transactions. Their central role in controlling the chromatin dynamics and transcription has been well-appreciated in several well-studied organisms. Here, we review the diversity, distribution, structure, and function of NAPs from the genus Mycobacterium. We highlight the progress made in our understanding of the effects of these proteins on various processes and in responding to environmental stimuli and stress of mycobacteria in their free-living as well as during distinctive intracellular lifestyles. We project them as potential drug targets and discuss future studies to bridge the information gap with NAPs from well-studied systems.
Collapse
Affiliation(s)
- Meghna Santoshi
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Priyanka Tare
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, India
- Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| |
Collapse
|
3
|
Wang W, Yue Y, Zhang M, Song N, Jia H, Dai Y, Zhang F, Li C, Li B. Host acid signal controls Salmonella flagella biogenesis through CadC-YdiV axis. Gut Microbes 2022; 14:2146979. [PMID: 36456534 PMCID: PMC9728131 DOI: 10.1080/19490976.2022.2146979] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Upon entering host cells, Salmonella quickly turns off flagella biogenesis to avoid recognition by the host immune system. However, it is not clear which host signal(s) Salmonella senses to initiate flagellum control. Here, we demonstrate that the acid signal can suppress flagella synthesis and motility of Salmonella, and this occurs after the transcription of master flagellar gene flhDC and depends on the anti-FlhDC factor YdiV. YdiV expression is activated after acid treatment. A global screen with ydiV promoter DNA and total protein from acid-treated Salmonella revealed a novel regulator of YdiV, the acid-related transcription factor CadC. Further studies showed that CadCC, the DNA binding domain of CadC, directly binds to a 33 nt region of the ydiV promoter with a 0.2 μM KD affinity. Furthermore, CadC could separate H-NS-ydiV promoter DNA complex to form CadC-DNA complex at a low concentration. Structural simulation and mutagenesis assays revealed that H43 and W106 of CadC are essential for ydiV promoter binding. No acid-induced flagellum control phenotype was observed in cadC mutant or ydiV mutant strains, suggesting that flagellum control during acid adaption is dependent on CadC and YdiV. The intracellular survival ability of cadC mutant strain decreased significantly compared with WT strain while the flagellin expression could not be effectively controlled in the cadC mutant strain when surviving within host cells. Together, our results demonstrated that acid stress acts as an important host signal to trigger Salmonella flagellum control through the CadC-YdiV-FlhDC axis, allowing Salmonella to sense a hostile environment and regulate flagellar synthesis during infection.
Collapse
Affiliation(s)
- Weiwei Wang
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yingying Yue
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Min Zhang
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Nannan Song
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Haihong Jia
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yuanji Dai
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Fengyu Zhang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Qingdao, China
| | - Cuiling Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Bingqing Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China,Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China,Shandong First Medical University, Key Lab for Biotech-Drugs of National Health Commission, Jinan, China,KeyLaboratory for Rare & Uncommon Diseases of Shandong Province, Jinan, China,CONTACT Bingqing Li Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan250021Shandong, China
| |
Collapse
|
4
|
Abstract
The DNA-binding protein from starved cells, Dps, is a universally conserved prokaryotic ferritin that, in many species, also binds DNA. Dps homologs have been identified in the vast majority of bacterial species and several archaea. Dps also may play a role in the global regulation of gene expression, likely through chromatin reorganization. Dps has been shown to use both its ferritin and DNA-binding functions to respond to a variety of environmental pressures, including oxidative stress. One mechanism that allows Dps to achieve this is through a global nucleoid restructuring event during stationary phase, resulting in a compact, hexacrystalline nucleoprotein complex called the biocrystal that occludes damaging agents from DNA. Due to its small size, hollow spherical structure, and high stability, Dps is being developed for applications in biotechnology.
Collapse
|
5
|
Sengupta S, Bhawsinghka N, Shaw R, Patra MM, Das Gupta SK. Mycobacteriophage D29 induced association of Mycobacterial RNA polymerase with ancillary factors leads to increased transcriptional activity. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35353035 DOI: 10.1099/mic.0.001158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mycobacteriophage D29 infects species belonging to the genus Mycobacterium including the deadly pathogen Mycobacterium tuberculosis. D29 is a lytic phage, although, related to the lysogenic mycobacteriophage L5. This phage is unable to lysogenize in mycobacteria as it lacks the gene encoding the phage repressor. Infection by many mycobacteriophages cause various changes in the host that ultimately leads to inactivation of the latter. One of the host targets often modified in the process is RNA polymerase. During our investigations with phage D29 infected Mycobacterium smegmatis (Msm) we observed that the promoters from both phage, and to a lesser extent those of the host were found to be more active in cells that were exposed to D29, as compared to the unexposed. Further experiments indicate that the RNA polymerase purified from phage infected cells possessed higher affinity for promoters particularly those that were phage derived. Comparison of the purified RNA polymerase preparations from infected and uninfected cells showed that several ancillary transcription factors, Sigma factor F, Sigma factor H, CarD and RbpA are prominently associated with the RNA polymerase from infected cells. Based on our observations we conclude that the higher activity of RNA polymerase observed in D29 infected cells is due to its increased association with ancillary transcription factors.
Collapse
Affiliation(s)
- Shreya Sengupta
- Department of Microbiology, Bose Institute, P-1/12 C.I.T Road. Scheme VIIM, Kolkata-700054, West Bengal, India
| | - Niketa Bhawsinghka
- Department of Microbiology, Bose Institute, P-1/12 C.I.T Road. Scheme VIIM, Kolkata-700054, West Bengal, India.,Present address: Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
| | - Rahul Shaw
- Department of Microbiology, Bose Institute, P-1/12 C.I.T Road. Scheme VIIM, Kolkata-700054, West Bengal, India
| | - Madhu Manti Patra
- Department of Microbiology, Bose Institute, P-1/12 C.I.T Road. Scheme VIIM, Kolkata-700054, West Bengal, India
| | - Sujoy K Das Gupta
- Department of Microbiology, Bose Institute, P-1/12 C.I.T Road. Scheme VIIM, Kolkata-700054, West Bengal, India
| |
Collapse
|
6
|
Wang W, Yue Y, Zhang M, Song N, Jia H, Dai Y, Zhang F, Li C, Li B. Host acid signal controls Salmonella flagella biogenesis through CadC-YdiV axis. Gut Microbes 2022. [PMID: 36456534 DOI: 10.1080/194909762125747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
Upon entering host cells, Salmonella quickly turns off flagella biogenesis to avoid recognition by the host immune system. However, it is not clear which host signal(s) Salmonella senses to initiate flagellum control. Here, we demonstrate that the acid signal can suppress flagella synthesis and motility of Salmonella, and this occurs after the transcription of master flagellar gene flhDC and depends on the anti-FlhDC factor YdiV. YdiV expression is activated after acid treatment. A global screen with ydiV promoter DNA and total protein from acid-treated Salmonella revealed a novel regulator of YdiV, the acid-related transcription factor CadC. Further studies showed that CadCC, the DNA binding domain of CadC, directly binds to a 33 nt region of the ydiV promoter with a 0.2 μM KD affinity. Furthermore, CadC could separate H-NS-ydiV promoter DNA complex to form CadC-DNA complex at a low concentration. Structural simulation and mutagenesis assays revealed that H43 and W106 of CadC are essential for ydiV promoter binding. No acid-induced flagellum control phenotype was observed in cadC mutant or ydiV mutant strains, suggesting that flagellum control during acid adaption is dependent on CadC and YdiV. The intracellular survival ability of cadC mutant strain decreased significantly compared with WT strain while the flagellin expression could not be effectively controlled in the cadC mutant strain when surviving within host cells. Together, our results demonstrated that acid stress acts as an important host signal to trigger Salmonella flagellum control through the CadC-YdiV-FlhDC axis, allowing Salmonella to sense a hostile environment and regulate flagellar synthesis during infection.
Collapse
Affiliation(s)
- Weiwei Wang
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yingying Yue
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Min Zhang
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Nannan Song
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Haihong Jia
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Yuanji Dai
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Fengyu Zhang
- State Key Laboratory of Microbial Technology, School of Life Sciences, Shandong University, Qingdao, China
| | - Cuiling Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
| | - Bingqing Li
- Department of Clinical Laboratory, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
- Department of Pathogen Biology, School of Clinical and Basic Medical Sciences, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, China
- Shandong First Medical University, Key Lab for Biotech-Drugs of National Health Commission, Jinan, China
- KeyLaboratory for Rare & Uncommon Diseases of Shandong Province, Jinan, China
| |
Collapse
|
7
|
|
8
|
Jeong H, Kim Y, Lee HS. OsnR is an autoregulatory negative transcription factor controlling redox-dependent stress responses in Corynebacterium glutamicum. Microb Cell Fact 2021; 20:203. [PMID: 34663317 PMCID: PMC8524982 DOI: 10.1186/s12934-021-01693-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 10/07/2021] [Indexed: 01/11/2023] Open
Abstract
Background Corynebacterium glutamicum is used in the industrial production of amino acids and nucleotides. During the course of fermentation, C. glutamicum cells face various stresses and employ multiple regulatory genes to cope with the oxidative stress. The osnR gene plays a negative regulatory role in redox-dependent oxidative-stress responses, but the underlying mechanism is not known yet. Results Overexpression of the osnR gene in C. glutamicum affected the expression of genes involved in the mycothiol metabolism. ChIP-seq analysis revealed that OsnR binds to the promoter region of multiple genes, including osnR and cg0026, which seems to function in the membrane-associated redox metabolism. Studies on the role of the osnR gene involving in vitro assays employing purified OsnR proteins and in vivo physiological analyses have identified that OsnR inhibits the transcription of its own gene. Further, oxidant diamide stimulates OsnR-binding to the promoter region of the osnR gene. The genes affected by the overexpression of osnR have been found to be under the control of σH. In the osnR-overexpressing strain, the transcription of sigH is significantly decreased and the stimulation of sigH transcription by external stress is lost, suggesting that osnR and sigH form an intimate regulatory network. Conclusions Our study suggests that OsnR not only functions as a transcriptional repressor of its own gene and of those involved in redox-dependent stress responses but also participates in the global transcriptional regulation by controlling the transcription of other master regulators, such as sigH. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-021-01693-1.
Collapse
Affiliation(s)
- Haeri Jeong
- Department of Biotechnology and Bioinformatics, Korea University, Sejong, Republic of Korea
| | - Younhee Kim
- Department of Korean Medicine, Semyung University, Jecheon, Chungbuk, Republic of Korea
| | - Heung-Shick Lee
- Department of Biotechnology and Bioinformatics, Korea University, Sejong, Republic of Korea.
| |
Collapse
|
9
|
Williams SM, Chatterji D. An Overview of Dps: Dual Acting Nanovehicles in Prokaryotes with DNA Binding and Ferroxidation Properties. Subcell Biochem 2021; 96:177-216. [PMID: 33252729 DOI: 10.1007/978-3-030-58971-4_3] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
DNA binding proteins under starvation (Dps) are proteins belonging to the ferritin family with the capacity for DNA binding, in addition to iron storage and ferroxidation. Present only in the prokaryotes, these multifaceted proteins have been assigned with a number of roles, from pathogenesis to nucleoid condensation and protection. They have a significant role in protecting the cells from free radical assaults, indirectly by sequestration of iron and by directly binding to the DNA. Due to their symmetry, stability and biomineralization capacity, these proteins have ever increasing potential applications in biotechnology and drug delivery. This chapter tries to bring together all these aspects of Dps in the view of current understanding and older perspectives by studies of our group as well as other experts in the field.
Collapse
Affiliation(s)
- Sunanda Margrett Williams
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, WC1E 7HX, United Kingdom.
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
| |
Collapse
|
10
|
Kamyshinsky R, Chesnokov Y, Dadinova L, Mozhaev A, Orlov I, Petoukhov M, Orekhov A, Shtykova E, Vasiliev A. Polymorphic Protective Dps-DNA Co-Crystals by Cryo Electron Tomography and Small Angle X-Ray Scattering. Biomolecules 2019; 10:biom10010039. [PMID: 31888079 PMCID: PMC7023142 DOI: 10.3390/biom10010039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/19/2019] [Accepted: 12/22/2019] [Indexed: 12/01/2022] Open
Abstract
Rapid increase of intracellular synthesis of specific histone-like Dps protein that binds DNA to protect the genome against deleterious factors leads to in cellulo crystallization—one of the most curious processes in the area of life science at the moment. However, the actual structure of the Dps–DNA co-crystals remained uncertain in the details for more than two decades. Cryo-electron tomography and small-angle X-ray scattering revealed polymorphous modifications of the co-crystals depending on the buffer parameters. Two different types of the Dps–DNA co-crystals are formed in vitro: triclinic and cubic. Three-dimensional reconstruction revealed DNA and Dps molecules in cubic co-crystals, and the unit cell parameters of cubic lattice were determined consistently by both methods.
Collapse
Affiliation(s)
- Roman Kamyshinsky
- National Research Center “Kurchatov Institute”, Akademika Kurchatova pl., 1, 123182 Moscow, Russia; (Y.C.); (A.O.); (A.V.)
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
- Moscow Institute of Physics and Technology, Institutsky lane 9, 141700 Dolgoprudny, Moscow Region, Russia
- Correspondence: ; Tel.: +7-916-356-3963
| | - Yury Chesnokov
- National Research Center “Kurchatov Institute”, Akademika Kurchatova pl., 1, 123182 Moscow, Russia; (Y.C.); (A.O.); (A.V.)
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
| | - Liubov Dadinova
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
| | - Andrey Mozhaev
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
- Shemyakin-Ovchinnikov Institute of bioorganic chemistry of Russian Academy of Sciences, Miklukho-Maklaya, 16/10, 117997 Moscow, Russia
| | - Ivan Orlov
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
| | - Maxim Petoukhov
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
- Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences, Leninsky prospect, 31, 119071 Moscow, Russia
| | - Anton Orekhov
- National Research Center “Kurchatov Institute”, Akademika Kurchatova pl., 1, 123182 Moscow, Russia; (Y.C.); (A.O.); (A.V.)
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
- Moscow Institute of Physics and Technology, Institutsky lane 9, 141700 Dolgoprudny, Moscow Region, Russia
| | - Eleonora Shtykova
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
| | - Alexander Vasiliev
- National Research Center “Kurchatov Institute”, Akademika Kurchatova pl., 1, 123182 Moscow, Russia; (Y.C.); (A.O.); (A.V.)
- Shubnikov Institute of Crystallography of Federal Scientific Research Centre “Crystallography and Photonics” of Russian Academy of Sciences, Leninskiy prospect, 59, 119333 Moscow, Russia; (L.D.); (A.M.); (I.O.); (M.P.); (E.S.)
- Moscow Institute of Physics and Technology, Institutsky lane 9, 141700 Dolgoprudny, Moscow Region, Russia
| |
Collapse
|
11
|
Williams SM, Chatterji D. Flexible aspartates propel iron to the ferroxidation sites along pathways stabilized by a conserved arginine in Dps proteins from Mycobacterium smegmatis. Metallomics 2018; 9:685-698. [PMID: 28418062 DOI: 10.1039/c7mt00008a] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
DNA-binding proteins under starvation (Dps) are dodecameric nano-compartments for iron oxidation and storage in bacterial cells. These proteins have roughly spherical structures with a hollow interior where iron is stored. Through mutational analysis of a conserved arginine residue in the second Dps protein from Mycobacterium smegmatis, we have identified residues which stabilize the interfaces between the iron entry and ferroxidation sites. Also, we have used X-ray crystallography to determine the structures of co-crystals of iron and Dps in varying proportions and compare the changes in these ligand-bound forms with respect to the apo-protein. The iron-loaded proteins of low, medium and high iron-bound forms were found to exhibit aspartate residues with alternate conformations, some of which could be directly linked to the sites of ferroxidation and iron entry. We conclude that the increased flexibility of aspartates in the presence of iron facilitates its movement from the entry site to the ferroxidaton site, and the two active sites are stabilized by the interactions of a conserved arginine residue R73.
Collapse
|
12
|
Application of Distributive Conjugal DNA Transfer in Mycobacterium smegmatis To Establish a Genome-Wide Synthetic Genetic Array. J Bacteriol 2017; 199:JB.00410-17. [PMID: 28784812 DOI: 10.1128/jb.00410-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 07/27/2017] [Indexed: 11/20/2022] Open
Abstract
Genetic redundancy can obscure phenotypic effects of single-gene mutations. Two individual mutations may be viable separately but are lethal when combined, thus synthetically linking the two gene products in an essential process. Synthetic genetic arrays (SGAs), in which defined mutations are combined, provide a powerful approach to identify novel genetic interactions and redundant pathways. A genome-scale SGA can offer an initial assignment of function to hypothetical genes by uncovering interactions with known genes or pathways. Here, we take advantage of the chromosomal conjugation system of Mycobacterium smegmatis to combine individual donor and recipient mutations on a genome-wide scale. We demonstrated the feasibility of a high-throughput mycobacterial SGA (mSGA) screen by using mutants of esx3, fxbA, and recA as query genes, which were combined with an arrayed library of transposon mutants by conjugation. The mSGA identified interacting genes that we had predicted and, most importantly, identified novel interacting genes-encoding both proteins and a noncoding RNA (ncRNA). In combination with other molecular genetic approaches, the mSGA has great potential to both reduce the high number of conserved hypothetical protein annotations in mycobacterial genomes and further define mycobacterial pathways and gene interactions.IMPORTANCE Mycobacterium smegmatis is the model organism of choice for the study of mycobacterial pathogens, because it is a fast-growing nonpathogenic species harboring many genes that are conserved throughout mycobacteria. In this work, we describe a synthetic genetic array (mSGA) approach for M. smegmatis, which combines mutations on a genome-wide scale with high efficiency. Analysis of the double mutant strains enables the identification of interacting genes and pathways that are normally hidden by redundant biological pathways. The mSGA is a powerful genetic tool that enables functions to be assigned to the many conserved hypothetical genes found in all mycobacterial species.
Collapse
|
13
|
YB-1 is elevated in medulloblastoma and drives proliferation in Sonic hedgehog-dependent cerebellar granule neuron progenitor cells and medulloblastoma cells. Oncogene 2016; 35:4256-68. [PMID: 26725322 PMCID: PMC4931992 DOI: 10.1038/onc.2015.491] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Revised: 10/26/2015] [Accepted: 11/27/2015] [Indexed: 12/29/2022]
Abstract
Postnatal proliferation of cerebellar granule neuron precursors (CGNPs), proposed cells of origin for the SHH-associated subgroup of medulloblastoma, is driven by Sonic hedgehog (Shh) and insulin-like growth factor (IGF) in the developing cerebellum. Shh induces the oncogene Yes-associated protein (YAP), which drives IGF2 expression in CGNPs and mouse Shh-associated medulloblastomas. To determine how IGF2 expression is regulated downstream of YAP, we carried out an unbiased screen for transcriptional regulators bound to IGF2 promoters. We report that Y-box binding protein-1 (YB-1), an onco-protein regulating transcription and translation, binds to IGF2 promoter P3. We observed that YB-1 is upregulated across human medulloblastoma subclasses as well as in other varieties of pediatric brain tumors. Utilizing the cerebellar progenitor model for the Shh subgroup of medulloblastoma in mice, we show for the first time that YB-1 is induced by Shh in CGNPs. Its expression is YAP-dependent and it is required for IGF2 expression in CGNPs. Finally, both gain-of function and loss-of-function experiments reveal that YB-1 activity is required for sustaining CGNP and medulloblastoma cell (MBC) proliferation. Collectively, our findings describe a novel role for YB-1 in driving proliferation in the developing cerebellum and MBCs and they identify the SHH:YAP:YB1:IGF2 axis as a powerful target for therapeutic intervention in medulloblastomas.
Collapse
|
14
|
Milecka D, Samluk A, Wasiak K, Krawczyk-Balska A. An essential role of a ferritin-like protein in acid stress tolerance of Listeria monocytogenes. Arch Microbiol 2014; 197:347-51. [PMID: 25352185 PMCID: PMC4326649 DOI: 10.1007/s00203-014-1053-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2014] [Revised: 09/01/2014] [Accepted: 10/22/2014] [Indexed: 12/15/2022]
Abstract
The expression of ten genes of Listeria monocytogenes previously identified as penicillin G-inducible was transcriptionally analyzed in the presence of 0.5 M KCl, pH 5.0 and 42 °C. This study revealed that all the genes are upregulated by osmotic stress, seven by acid stress and four by temperature stress conditions. The contribution of a gene encoding a ferritin-like protein (fri), a two-component phosphate-response regulator (phoP) and an AraC/XylS family transcription regulator (axyR) to temperature, acid and osmotic stress tolerance was further examined by analysis of nonpolar deletion mutants. This revealed that a lack of PhoP or AxyR does not affect the ability to grow under the tested stress conditions. However, the Δ fri strain showed slightly delayed growth under osmotic and clearly impaired growth under acid stress conditions, indicating an important role of the ferritin-like protein in acid stress tolerance.
Collapse
Affiliation(s)
- Dorota Milecka
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland
| | | | | | | |
Collapse
|
15
|
Mitra A, Misquitta R, Nagaraja V. Mycobacterium tuberculosis Rho is an NTPase with distinct kinetic properties and a novel RNA-binding subdomain. PLoS One 2014; 9:e107474. [PMID: 25229539 PMCID: PMC4167861 DOI: 10.1371/journal.pone.0107474] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/18/2014] [Indexed: 11/29/2022] Open
Abstract
Two mechanisms--factor independent and dependent termination--ensure the completion of RNA synthesis in eubacteria. Factor-dependent mechanism relies on the Rho protein to terminate transcription by interacting with RNA polymerase. Although well studied in Escherichia coli, the properties of the Rho homologs from most bacteria are not known. The rho gene is unusually large in genus Mycobacterium and other members of actinobacteria, having ∼150 additional residues towards the amino terminal end. We describe the distinct properties of Rho from Mycobacterium tuberculosis. It is an NTPase with a preference for purine nucleoside triphosphates with kinetic properties different from E. coli homolog and an ability to use various RNA substrates. The N-terminal subdomain of MtbRho can bind to RNA by itself, and appears to contribute to the interaction of the termination factor with RNAs. Furthermore, the interaction with RNA induces changes in conformation and oligomerization of MtbRho.
Collapse
Affiliation(s)
- Anirban Mitra
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Rachel Misquitta
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - Valakunja Nagaraja
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
- Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| |
Collapse
|
16
|
Sharma IM, Prakash S, Dhanaraman T, Chatterji D. Characterization of a dual-active enzyme, DcpA, involved in cyclic diguanosine monophosphate turnover in Mycobacterium smegmatis. MICROBIOLOGY-SGM 2014; 160:2304-2318. [PMID: 25037163 DOI: 10.1099/mic.0.080200-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We have reported previously that the long-term survival of Mycobacterium smegmatis is facilitated by a dual-active enzyme MSDGC-1 (renamed DcpA), which controls the cellular turnover of cyclic diguanosine monophosphate (c-di-GMP). Most mycobacterial species possess at least a single copy of a DcpA orthologue that is highly conserved in terms of sequence similarity and domain architecture. Here, we show that DcpA exists in monomeric and dimeric forms. The dimerization of DcpA is due to non-covalent interactions between two protomers that are arranged in a parallel orientation. The dimer shows both synthesis and hydrolysis activities, whereas the monomer shows only hydrolysis activity. In addition, we have shown that DcpA is associated with the cytoplasmic membrane and exhibits heterogeneous cellular localization with a predominance at the cell poles. Finally, we have also shown that DcpA is involved in the change in cell length and colony morphology of M. smegmatis. Taken together, our study provides additional evidence about the role of the bifunctional protein involved in c-di-GMP signalling in M. smegmatis.
Collapse
Affiliation(s)
- Indra Mani Sharma
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Sunita Prakash
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Thillaivillalan Dhanaraman
- Institute for Research in Immunology and Cancer, Université de Montréal, Montréal H3C 3J7, Québec, Canada
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| |
Collapse
|
17
|
Williams SM, Chandran AV, Vijayabaskar MS, Roy S, Balaram H, Vishveshwara S, Vijayan M, Chatterji D. A histidine aspartate ionic lock gates the iron passage in miniferritins from Mycobacterium smegmatis. J Biol Chem 2014; 289:11042-11058. [PMID: 24573673 PMCID: PMC4036245 DOI: 10.1074/jbc.m113.524421] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 02/24/2014] [Indexed: 11/06/2022] Open
Abstract
Dps (DNA-binding protein from starved cells) are dodecameric assemblies belonging to the ferritin family that can bind DNA, carry out ferroxidation, and store iron in their shells. The ferritin-like trimeric pore harbors the channel for the entry and exit of iron. By representing the structure of Dps as a network we have identified a charge-driven interface formed by a histidine aspartate cluster at the pore interface unique to Mycobacterium smegmatis Dps protein, MsDps2. Site-directed mutagenesis was employed to generate mutants to disrupt the charged interactions. Kinetics of iron uptake/release of the wild type and mutants were compared. Crystal structures were solved at a resolution of 1.8-2.2 Å for the various mutants to compare structural alterations vis à vis the wild type protein. The substitutions at the pore interface resulted in alterations in the side chain conformations leading to an overall weakening of the interface network, especially in cases of substitutions that alter the charge at the pore interface. Contrary to earlier findings where conserved aspartate residues were found crucial for iron release, we propose here that in the case of MsDps2, it is the interplay of negative-positive potentials at the pore that enables proper functioning of the protein. In similar studies in ferritins, negative and positive patches near the iron exit pore were found to be important in iron uptake/release kinetics. The unique ionic cluster in MsDps2 makes it a suitable candidate to act as nano-delivery vehicle, as these gated pores can be manipulated to exhibit conformations allowing for slow or fast rates of iron release.
Collapse
Affiliation(s)
| | - Anu V Chandran
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Mahalingam S Vijayabaskar
- School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom, and
| | - Sourav Roy
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Hemalatha Balaram
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | | | - Mamannamana Vijayan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India,; Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India.
| |
Collapse
|
18
|
Bharati BK, Swetha RK, Chatterji D. Identification and characterization of starvation induced msdgc-1 promoter involved in the c-di-GMP turnover. Gene 2013; 528:99-108. [PMID: 23932989 DOI: 10.1016/j.gene.2013.07.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/25/2013] [Accepted: 07/09/2013] [Indexed: 11/17/2022]
Abstract
C-di-GMP [Bis-(3'-5')-cyclic-dimeric-guanosine monophosphate], a second messenger is involved in intracellular communication in the bacterial species. As a result several multi-cellular behaviors in both Gram-positive and Gram-negative bacteria are directly linked to the intracellular level of c-di-GMP. The cellular concentration of c-di-GMP is maintained by two opposing activities, diguanylate cyclase (DGC) and phosphodiesterase (PDE-A). In Mycobacterium smegmatis, a single bifunctional protein MSDGC-1 is responsible for the cellular concentration of c-di-GMP. A better understanding of the regulation of c-di-GMP at the genetic level is necessary to control the function of above two activities. In this work, we have characterized the promoter element present in msdgc-1 along with the +1 transcription start site and identified the sigma factors that regulate the transcription of msdgc-1. Interestingly, msdgc-1 utilizes SigA during the initial phase of growth, whereas near the stationary phase SigB containing RNA polymerase takes over the expression of msdgc-1. We report here that the promoter activity of msdgc-1 increases during starvation or depletion of carbon source like glucose or glycerol. When msdgc-1 is deleted, the numbers of viable cells are ~10 times higher in the stationary phase in comparison to that of the wild type. We propose here that msdgc-1 is involved in the regulation of cell population density.
Collapse
Affiliation(s)
- Binod K Bharati
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | | | | |
Collapse
|
19
|
Facey PD, Hitchings MD, Williams JS, Skibinski DOF, Dyson PJ, Del Sol R. The evolution of an osmotically inducible dps in the genus Streptomyces. PLoS One 2013; 8:e60772. [PMID: 23560105 PMCID: PMC3613396 DOI: 10.1371/journal.pone.0060772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 03/02/2013] [Indexed: 11/25/2022] Open
Abstract
Dps proteins are found almost ubiquitously in bacterial genomes and there is now an appreciation of their multifaceted roles in various stress responses. Previous studies have shown that this family of proteins assemble into dodecamers and their quaternary structure is entirely critical to their function. Moreover, the numbers of dps genes per bacterial genome is variable; even amongst closely related species - however, for many genera this enigma is yet to be satisfactorily explained. We reconstruct the most probable evolutionary history of Dps in Streptomyces genomes. Typically, these bacteria encode for more than one Dps protein. We offer the explanation that variation in the number of dps per genome among closely related Streptomyces can be explained by gene duplication or lateral acquisition, and the former preceded a subsequent shift in expression patterns for one of the resultant paralogs. We show that the genome of S. coelicolor encodes for three Dps proteins including a tailless Dps. Our in vivo observations show that the tailless protein, unlike the other two Dps in S. coelicolor, does not readily oligomerise. Phylogenetic and bioinformatic analyses combined with expression studies indicate that in several Streptomyces species at least one Dps is significantly over-expressed during osmotic shock, but the identity of the ortholog varies. In silico analysis of dps promoter regions coupled with gene expression studies of duplicated dps genes shows that paralogous gene pairs are expressed differentially and this correlates with the presence of a sigB promoter. Lastly, we identify a rare novel clade of Dps and show that a representative of these proteins in S. coelicolor possesses a dodecameric quaternary structure of high stability.
Collapse
Affiliation(s)
- Paul D Facey
- Institute of Life Science, College of Medicine, Swansea University, Swansea, United Kingdom.
| | | | | | | | | | | |
Collapse
|
20
|
Li SK, Ng PKS, Qin H, Lau JKY, Lau JPY, Tsui SKW, Chan TF, Lau TCK. Identification of small RNAs in Mycobacterium smegmatis using heterologous Hfq. RNA (NEW YORK, N.Y.) 2013; 19:74-84. [PMID: 23169799 PMCID: PMC3527728 DOI: 10.1261/rna.034116.112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Accepted: 10/22/2012] [Indexed: 05/30/2023]
Abstract
Gene regulation by small RNAs (sRNAs) has been extensively studied in various bacteria. However, the presence and roles of sRNAs in mycobacteria remain largely unclear. Immunoprecipitation of RNA chaperone Hfq to enrich for sRNAs is one of the effective methods to isolate sRNAs. However, the lack of an identified mycobacterial hfq restricts the feasibility of this approach. We developed a novel method that takes advantage of the conserved inherent sRNAs-binding capability of heterologous Hfq from Escherichia coli to enrich sRNAs from Mycobacterium smegmatis, a model organism for studying Mycobacterium tuberculosis. We validated 12 trans-encoded and 12 cis-encoded novel sRNAs in M. smegmatis. Many of these sRNAs are differentially expressed at exponential phase compared with stationary phase, suggesting that sRNAs are involved in the growth of mycobacteria. Intriguingly, five of the cis-encoded novel sRNAs target known transposases. Phylogenetic conservation analysis shows that these sRNAs are pathogenicity dependent. We believe that our findings will serve as an important reference for future analysis of sRNAs regulation in mycobacteria and will contribute significantly to the development of sRNAs prediction programs. Moreover, this novel method of using heterologous Hfq for sRNAs enrichment can be of general use for the discovery of bacterial sRNAs in which no endogenous Hfq is identified.
Collapse
Affiliation(s)
- Sai-Kam Li
- Department of Biology and Chemistry, City University of Hong Kong, Hong Kong SAR
| | | | - Hao Qin
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong SAR
| | - Jeffrey Kwan-Yiu Lau
- Department of Biology and Chemistry, City University of Hong Kong, Hong Kong SAR
| | | | | | - Ting-Fung Chan
- School of Life Sciences, The Chinese University of Hong Kong, Hong Kong SAR
| | | |
Collapse
|
21
|
Newton-Foot M, Gey van Pittius NC. The complex architecture of mycobacterial promoters. Tuberculosis (Edinb) 2012; 93:60-74. [PMID: 23017770 DOI: 10.1016/j.tube.2012.08.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Revised: 07/31/2012] [Accepted: 08/06/2012] [Indexed: 01/02/2023]
Abstract
The genus Mycobacterium includes a variety of species with differing phenotypic properties, including growth rate, pathogenicity and environment- and host-specificity. Although many mycobacterial species have been extensively studied and their genomes sequenced, the reasons for phenotypic variation between closely related species remain unclear. Variation in gene expression may contribute to these characteristics and enable the bacteria to respond to changing environmental conditions. Gene expression is controlled primarily at the level of transcription, where the main element of regulation is the promoter. Transcriptional regulation and associated promoter sequences have been studied extensively in E. coli. This review describes the complex structure and characteristics of mycobacterial promoters, in comparison to the classical E. coli prokaryotic promoter structure. Some components of mycobacterial promoters are similar to those of E. coli. These include the predominant guanine residue at the transcriptional start point, conserved -10 hexamer, similar interhexameric distances, the use of ATG as a start codon, the guanine- and adenine-rich ribosome binding site and the presence of extended -10 (TGn) motifs in strong promoters. However, these components are much more variable in sequence in mycobacterial promoters and no conserved -35 hexamer sequence (clearly defined in E. coli) can be identified. This may be a result of the high G+C content of mycobacterial genomes, as well as the large number of sigma factors present in mycobacteria, which may recognise different promoter sequences. Mycobacteria possess a complex transcriptional regulatory network. Numerous regulatory motifs have been identified in mycobacterial promoters, predominantly in the interhexameric region. These are bound by specific transcriptional regulators in response to environmental changes. The combination of specific promoter sequences, transcriptional regulators and a variety of sigma factors enables rapid and specific responses to diverse conditions and different stages of infection. This review aims to provide an overview of the complex architecture of mycobacterial transcriptional regulation.
Collapse
Affiliation(s)
- Mae Newton-Foot
- DST/NRF Centre of Excellence for Biomedical Tuberculosis Research/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, PO Box 19063, Francie van Zijl Drive, Tygerberg 7505, South Africa.
| | | |
Collapse
|
22
|
Ganguly A, Chatterji D. Sequential assembly of an active RNA polymerase molecule at the air-water interface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:3808-3814. [PMID: 21395266 DOI: 10.1021/la200225t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
At the heart of understanding cellular processes lies our ability to explore the specific nature of communication between sequential information carrying biopolymers. However, the data extracted from conventional solution phase studies may not reflect the dynamics of communication between recognized partners as they occur in the crowded cellular milieu. We use the principle of immobilization of histidine-tagged biopolymers at a Ni(II)-encoded Langmuir monolayer to study sequence-specific protein-protein interactions in an artificially crowded environment. The advantage of this technique lies in increasing the surface density of one of the interacting partners that allows us to study macromolecular interactions in a controlled crowded environment, but without compromising the speed of the reactions. We have taken advantage of this technique to follow the sequential assembly process of the multiprotein complex Escherichia coli RNA polymerase at the interface and also deciphered the role of one of the proteins, omega (ω), in the assembly pathway. Our reconstitution studies indicate that in the absence of molecular chaperones or other cofactors, omega (ω) plays a decisive role in refolding the largest protein beta prime (β') and its recruitment into the multimeric assembly to reconstitute an active RNA polymerase. It was also observed that the monolayer had the ability to distinguish between sequence-specific and -nonspecific interactions despite the immobilization of one of the biomacromolecules. The technique provides a universal two-dimensional template for studying protein-ligand interactions while mimicking molecular crowding.
Collapse
Affiliation(s)
- Abantika Ganguly
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560012, India
| | | |
Collapse
|
23
|
Joon M, Bhatia S, Pasricha R, Bose M, Brahmachari V. Functional analysis of an intergenic non-coding sequence within mce1 operon of M.tuberculosis. BMC Microbiol 2010; 10:128. [PMID: 20420720 PMCID: PMC2867952 DOI: 10.1186/1471-2180-10-128] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Accepted: 04/27/2010] [Indexed: 11/29/2022] Open
Abstract
Background The mce operons play an important role in the entry of M. tuberculosis into macrophages and non-phagocytic cells. Their non-redundant function as well as complex regulation is implied by the phenotype of mce mutants. Recently, mce1 operon was found to extend over 13 genes, fadD5 (Rv0166) being the first gene of the operon. The presence of a non-coding sequence of 200 base pairs between Rv0166 and Rv0167 is peculiar to mce1 among the four mce operons of M.tuberculosis. We have examined the function of this region. Results We predicted putative promoter activity of the 200 base pairs of non-coding, intergenic region between Rv0166 and Rv0167 in silico using MEME software and designate it as intergenic promoter, IGPr. We demonstrate both promoter activity and a putative negative regulatory function of this fragment by reporter assays carried out in the surrogate host M.smegmatis. We find that the repressive elements not only control the native promoter but also repress a heterologous promoter of M.smegmatis. The higher activity of the intergenic promoter in a clinical isolate in comparison with the wild type sequence from M.tuberculosis H37Rv could be correlated with a point mutation within the negative element. We have mapped two transcription start sites for mce1 operon both of which are utilized in M.tuberculosis H37Rv as well as the clinical isolate VPCI591. Our studies show that the promoter activity in the non-coding region is relevant not only in reporter gene expression but also in the expression of mce1 operon in M. tuberculosis cells grown in synthetic medium. Conclusion The mce operon of M.tuberculosis H37Rv potentially can be transcribed from two promoters P1 and P2, former mapping upstream of Rv0166 and the latter in the non-coding intergenic region between Rv0166 and Rv0167. The transcription initiation from P1 results in a transcript with Rv0166 while that from P2 will be without it. The sequences between the translation start site of Rv0167 and the promoter P2 have a negative regulatory role, as point mutation within the sequence leads to enhanced activity of P2 as well as a heterologous promoter from M.smegmatis. The mutation detected in the clinical isolate VPCI591 therefore behaves like a gain-of-function mutation.
Collapse
Affiliation(s)
- Monika Joon
- Dr B R Ambedkar Centre for Biomedical Research, University of Delhi, Delhi-110007, India
| | | | | | | | | |
Collapse
|
24
|
Chowdhury RP, Saraswathi R, Chatterji D. Mycobacterial stress regulation: The Dps "twin sister" defense mechanism and structure-function relationship. IUBMB Life 2010; 62:67-77. [PMID: 20014234 DOI: 10.1002/iub.285] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In this work, we have tried to emphasize the connection between mycobacterial growth and regulation of gene expression. Utilization of multiple carbon sources and diauxic growth helps bacteria to regulate gene expression at an optimum level so that the inhospitable conditions encountered during nutrient depletion can be circumvented. These aspects will be discussed with respect to mycobacterial growth in subsequent sections. Identification and characterization of genes induced under such conditions is helpful to understand the physiology of the bacterium. Although it is necessary to compare the total expression profile of proteins as they transit from vegetative growth to stationary phase, at times a lot of insights can be deciphered from the expression pattern of one or two proteins. We have compared the protein expression and sigma factor selectivity of two such proteins in M. smegmatis to understand the differential regulation of genes playing diverse function in the same species. Some newer insights on the structure and function of one of the Dps proteins are also explained.
Collapse
|
25
|
The SigF regulon in Mycobacterium smegmatis reveals roles in adaptation to stationary phase, heat, and oxidative stress. J Bacteriol 2010; 192:2491-502. [PMID: 20233930 DOI: 10.1128/jb.00035-10] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SigF is an alternative sigma factor that is highly conserved among species of the genus Mycobacterium. In this study we identified the SigF regulon in Mycobacterium smegmatis using whole-genome microarray and promoter consensus analyses. In total, 64 genes in exponential phase and 124 genes in stationary phase are SigF dependent (P < 0.01, >2-fold expression change). Our experimental data reveal the SigF-dependent promoter consensus GTTT-N((15-17))-GGGTA for M. smegmatis, and we propose 130 potential genes under direct control of SigF, of which more than 50% exhibited reduced expression in a Delta sigF strain. We previously reported an increased susceptibility of the Delta sigF strain to heat and oxidative stress, and our expression data indicate a molecular basis for these phenotypes. We observed SigF-dependent expression of several genes purportedly involved in oxidative stress defense, namely, a heme-containing catalase, a manganese-containing catalase, a superoxide dismutase, the starvation-induced DNA-protecting protein MsDps1, and the biosynthesis genes for the carotenoid isorenieratene. Our data suggest that SigF regulates the biosynthesis of the thermoprotectant trehalose, as well as an uptake system for osmoregulatory compounds, and this may explain the increased heat susceptibility of the Delta sigF strain. We identified the regulatory proteins SigH3, PhoP, WhiB1, and WhiB4 as possible genes under direct control of SigF and propose four novel anti-sigma factor antagonists that could be involved in the posttranslational regulation of SigF in M. smegmatis. This study emphasizes the importance of this sigma factor for stationary-phase adaptation and stress response in mycobacteria.
Collapse
|
26
|
Saraswathi R, Pait Chowdhury R, Williams SM, Ghatak P, Chatterji D. The mycobacterial MsDps2 protein is a nucleoid-forming DNA binding protein regulated by sigma factors sigma and sigma. PLoS One 2009; 4:e8017. [PMID: 19956571 PMCID: PMC2779847 DOI: 10.1371/journal.pone.0008017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 10/29/2009] [Indexed: 11/19/2022] Open
Abstract
The Dps (DNA-binding protein from starved cells) proteins from Mycobacterium smegmatis MsDps1 and MsDps2 are both DNA-binding proteins with some differences. While MsDps1 has two oligomeric states, with one of them responsible for DNA binding, MsDps2 has only one DNA-binding oligomeric state. Both the proteins however, show iron-binding activity. The MsDps1 protein has been shown previously to be induced under conditions of starvation and osmotic stress and is regulated by the extra cellular sigma factors sigma(H) and sigma(F). We show here, that the second Dps homologue in M. smegmatis, namely MsDps2, is purified in a DNA-bound form and exhibits nucleoid-like structures under the atomic force microscope. It appears that the N-terminal sequence of Dps2 plays a role in nucleoid formation. MsDps2, unlike MsDps1, does not show elevated expression in nutritionally starved or stationary phase conditions; rather its promoter is recognized by RNA polymerase containing sigma(A) or sigma(B), under in vitro conditions. We propose that due to the nucleoid-condensing ability, the expression of MsDps2 is tightly regulated inside the cells.
Collapse
Affiliation(s)
| | | | | | - Payel Ghatak
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
- * E-mail:
| |
Collapse
|
27
|
Dey A, Verma AK, Chatterji D. Role of an RNA polymerase interacting protein, MsRbpA, from Mycobacterium smegmatis in phenotypic tolerance to rifampicin. MICROBIOLOGY-SGM 2009; 156:873-883. [PMID: 19926651 DOI: 10.1099/mic.0.033670-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Rifampicin and its derivatives are at the forefront of the current standard chemotherapeutic regimen for active tuberculosis; they act by inhibiting the transcription activity of prokaryotic RNA polymerase. Rifampicin is believed to interact with the beta subunit of RNA polymerase. However, it has been observed that protein-protein interactions with RNA polymerase core enzyme lead to its reduced susceptibility to rifampicin. This mechanism became more diversified with the discovery of RbpA, a novel RNA polymerase-binding protein, in Streptomyces coelicolor that could mitigate the effect of rifampicin on RNA polymerase activity. MsRbpA is a homologue of RbpA in Mycobacterium smegmatis. On deciphering the role of MsRbpA in M. smegmatis we found that it interacts with RNA polymerase and increases the rifampicin tolerance levels, both in vitro and in vivo. It interacts with the beta subunit of RNA polymerase. However, it was found to be incapable of rescuing rifampicin-resistant RNA polymerases in the presence of rifampicin at the respective IC(50).
Collapse
Affiliation(s)
- Abhinav Dey
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Amit Kumar Verma
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Dipankar Chatterji
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| |
Collapse
|
28
|
Differential expression of sigH paralogs during growth and under different stress conditions in Mycobacterium smegmatis. J Bacteriol 2009; 191:2888-93. [PMID: 19218386 DOI: 10.1128/jb.01773-08] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SigH regulates a transcriptional network that responds to heat and oxidative stress in mycobacteria. Seven sigH paralogs are reported to exist in the Mycobacterium smegmatis genome. A comprehensive real-time reverse transcriptase PCR analysis during different stages of growth and upon exposure to various stress conditions and antimycobacterial compounds showed differential expression of sigH paralogs during stationary phase and severalfold increases in the levels of transcription of sigH1, sigH4, sigH5, sigH6, and sigH7 under specific stress conditions.
Collapse
|
29
|
Gebhard S, Hümpel A, McLellan AD, Cook GM. The alternative sigma factor SigF of Mycobacterium smegmatis is required for survival of heat shock, acidic pH and oxidative stress. MICROBIOLOGY-SGM 2008; 154:2786-2795. [PMID: 18757812 DOI: 10.1099/mic.0.2008/018044-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The alternative sigma factor SigF of Mycobacterium tuberculosis has been characterized in detail as a general-stress, stationary-phase sigma factor involved in the virulence of the bacterium. While a homologous gene has been annotated in the genome of the fast-growing Mycobacterium smegmatis, little experimental evidence is available on the function of this gene. Here, we demonstrate that SigF of M. smegmatis is required for resistance to hydrogen peroxide, heat shock and acidic pH, but not for survival in human neutrophils. No difference in sensitivity to isoniazid was observed between the wild-type strain and the DeltasigF mutant, suggesting that SigF-mediated resistance to hydrogen peroxide was via a pathway independent of KatG or AhpC. RT-PCR and 5'-RACE (rapid amplification of cDNA ends) analyses showed that sigF of M. smegmatis was co-transcribed with rsbW (thought to encode an anti-sigma factor for SigF) and MSMEG_1802 (unknown function) and was expressed from two promoters, one upstream of MSMEG_1802 and the second upstream of rsbW. Analysis of transcriptional lacZ fusion constructs in the sigF-deletion background revealed that the MSMEG_1802 promoter was dependent on SigF for expression. Moreover, MSMEG_1802-lacZ was induced twofold upon entry into stationary phase, while exposure of exponentially growing cultures to various stress conditions (e.g. heat, cold, ethanol, hydrogen peroxide or different pH values) did not lead to induction of MSMEG_1802-lacZ. Expression of rsbW-lacZ was independent of SigF and remained constant throughout the growth cycle and under various stress conditions unless the bacteria were challenged with d-cycloserine.
Collapse
Affiliation(s)
- Susanne Gebhard
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin, New Zealand
| | - Anja Hümpel
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin, New Zealand
| | - Alexander D McLellan
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin, New Zealand
| | - Gregory M Cook
- Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, PO Box 56, Dunedin, New Zealand
| |
Collapse
|
30
|
Interaction of DevR with multiple binding sites synergistically activates divergent transcription of narK2-Rv1738 genes in Mycobacterium tuberculosis. J Bacteriol 2008; 190:5394-403. [PMID: 18502855 DOI: 10.1128/jb.00488-08] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Under hypoxic conditions or upon exposure to low concentrations of nitric oxide, DevR transcriptional regulator mediates the activation of approximately 50 genes that are believed to assist in dormancy development in Mycobacterium tuberculosis. Most of the strongly induced genes are characterized by the presence of one to four copies of a Dev box-like sequence at an upstream location. Among these are several gene pairs that are transcribed in opposite directions. This arrangement could provide for coordinated control of the adjacent genes under inducing conditions. In this work, we report the first detailed analysis of DevR-mediated hypoxic regulation of narK2-Rv1738 genes that are oppositely oriented in M. tuberculosis. Phosphorylated DevR interacts with intergenic sequences and protects approximately 80 bp of DNA that contains three binding sites, designated Dev boxes D1, D2, and D3. The hypoxia-specific transcription start points of narK2 and Rv1738 were mapped, and it was noted that the -35 elements of both promoters overlapped with the proximally placed Dev box. DevR bound cooperatively to adjacently placed D2 and D3 boxes while binding to D1 was independent of DevR interaction with the D2 and D3 boxes. Mutational analysis and green fluorescent protein reporter assays established that the three Dev boxes function synergistically to mediate maximal transcriptional induction of both narK2 and Rv1738 in hypoxic cultures of M. tuberculosis. Analysis of narK2 promoter activity indicates that it is under negative regulation in addition to DevR-mediated positive regulation and also reveals differences between M. tuberculosis and Mycobacterium bovis BCG.
Collapse
|
31
|
Mukherjee R, Chatterji D. Stationary phase induced alterations in mycobacterial RNA polymerase assembly: A cue to its phenotypic resistance towards rifampicin. Biochem Biophys Res Commun 2008; 369:899-904. [DOI: 10.1016/j.bbrc.2008.02.118] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2008] [Accepted: 02/25/2008] [Indexed: 10/22/2022]
|