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Armianinova DK, Karpov DS, Kotliarova MS, Goncharenko AV. Genetic Engineering in Mycobacteria. Mol Biol 2022. [DOI: 10.1134/s0026893322060036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Abstract
Genetic tools for targeted modification of the mycobacterial genome contribute to the understanding of the physiology and virulence mechanisms of mycobacteria. Human and animal pathogens, such as the Mycobacterium tuberculosis complex, which causes tuberculosis, and M. leprae, which causes leprosy, are of particular importance. Genetic research opens up novel opportunities to identify and validate new targets for antibacterial drugs and to develop improved vaccines. Although mycobacteria are difficult to work with due to their slow growth rate and a limited possibility to transfer genetic information, significant progress has been made in developing genetic engineering methods for mycobacteria. The review considers the main approaches to changing the mycobacterial genome in a targeted manner, including homologous and site-specific recombination and use of the CRISPR/Cas system.
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Qu D, Zhao X, Sun Y, Wu FL, Tao SC. Mycobacterium tuberculosis Thymidylyltransferase RmlA Is Negatively Regulated by Ser/Thr Protein Kinase PknB. Front Microbiol 2021; 12:643951. [PMID: 33868202 PMCID: PMC8044546 DOI: 10.3389/fmicb.2021.643951] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 02/28/2021] [Indexed: 11/13/2022] Open
Abstract
Ser/Thr phosphorylation by serine/threonine protein kinases (STPKs) plays significant roles in molecular regulation, which allows Mycobacteria to adapt their cell wall structure in response to the environment changes. Identifying direct targets of STPKs and determining their activities are therefore critical to revealing their function in Mycobacteria, for example, in cell wall formation and virulence. Herein, we reported that RmlA, a crucial L-rhamnose biosynthesis enzyme, is a substrate of STPK PknB in Mycobacterium tuberculosis (M. tuberculosis). Mass spectrometry analysis revealed that RmlA is phosphorylated at Thr-12, Thr-54, Thr-197, and Thr-12 is located close to the catalytic triad of RmlA. Biochemical and phenotypic analysis of two RmlA mutants, T12A/T12D, showed that their activities were reduced, and cell wall formation was negatively affected. Moreover, virulence of RmlA T12D mutant was attenuated in a macrophage model. Overall, these results provide the first evidence for the role of PknB-dependent RmlA phosphorylation in regulating cell wall formation in Mycobacteria, with significant implications for pathogenicity.
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Affiliation(s)
- Dehui Qu
- Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in Universities of Shandong, School of Agriculture, Ludong University, Yantai, China.,State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaohui Zhao
- Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in Universities of Shandong, School of Agriculture, Ludong University, Yantai, China
| | - Yao Sun
- Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in Universities of Shandong, School of Agriculture, Ludong University, Yantai, China
| | - Fan-Lin Wu
- Key Laboratory of Molecular Module-Based Breeding of High Yield and Abiotic Resistant Plants in Universities of Shandong, School of Agriculture, Ludong University, Yantai, China
| | - Sheng-Ce Tao
- Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
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3
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Brown AC. Gene Switching and Essentiality Testing. Methods Mol Biol 2021; 2314:285-299. [PMID: 34235659 DOI: 10.1007/978-1-0716-1460-0_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The identification of essential genes is of major importance to mycobacterial research, and a number of essential genes have been identified in mycobacteria, however confirming essentiality is not straightforward, as deletion of essential genes results in a lethal phenotype. In this chapter, protocols are described which can be used to confirm gene essentiality using gene switching, following the construction of a strain carrying its only functional copy on an integrated plasmid (Δ'int). Since deletion mutants cannot be created for essential genes, a second gene copy is introduced via an integrating vector, which allows the chromosomal gene copy to be deleted. The integrated vector can then be replaced using the gene switching method, where no transformants are obtained, essentiality is confirmed. This technique can also be used to confirm functionality of gene homologs and to easily identify essential operon members.
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Affiliation(s)
- Amanda Claire Brown
- Texas A&M Veterinary Medical Diagnostic Laboratory (TVDML), College Station, TX, USA.
- Department of Animal Science, Texas A&M University, Kleberg Center, College Station, TX, USA.
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Borgers K, Vandewalle K, Van Hecke A, Michielsen G, Plets E, van Schie L, Vanmarcke S, Schindfessel L, Festjens N, Callewaert N. Development of a Counterselectable Transposon To Create Markerless Knockouts from an 18,432-Clone Ordered Mycobacterium bovis Bacillus Calmette-Guérin Mutant Resource. mSystems 2020; 5:e00180-20. [PMID: 32788404 PMCID: PMC7426150 DOI: 10.1128/msystems.00180-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 07/20/2020] [Indexed: 12/02/2022] Open
Abstract
Mutant resources are essential to improve our understanding of the biology of slow-growing mycobacteria, which include the causative agents of tuberculosis in various species, including humans. The generation of deletion mutants in slow-growing mycobacteria in a gene-by-gene approach in order to make genome-wide ordered mutant resources is still a laborious and costly approach, despite the recent development of improved methods. On the other hand, transposon mutagenesis in combination with Cartesian pooling-coordinate sequencing (CP-CSeq) allows the creation of large archived Mycobacterium transposon insertion libraries. However, such mutants contain selection marker genes with a risk of polar gene effects, which are undesired both for research and for use of these mutants as live attenuated vaccines. In this paper, a derivative of the Himar1 transposon is described which allows the generation of clean, markerless knockouts from archived transposon libraries. By incorporating FRT sites for FlpE/FRT-mediated recombination and I-SceI sites for ISceIM-based transposon removal, we enable two thoroughly experimentally validated possibilities to create unmarked mutants from such marked transposon mutants. The FRT approach is highly efficient but leaves an FRT scar in the genome, whereas the I-SceI-mediated approach can create mutants without any heterologous DNA in the genome. The combined use of CP-CSeq and this optimized transposon was applied in the BCG Danish 1331 vaccine strain (WHO reference 07/270), creating the largest ordered, characterized resource of mutants in a member of the Mycobacterium tuberculosis complex (18,432 clones, mutating 83% of the nonessential M. tuberculosis homologues), from which markerless knockouts can be easily generated.IMPORTANCE While speeding up research for many fields of biology (e.g., yeast, plant, and Caenorhabditis elegans), genome-wide ordered mutant collections are still elusive in mycobacterial research. We developed methods to generate such resources in a time- and cost-effective manner and developed a newly engineered transposon from which unmarked mutants can be efficiently generated. Our library in the WHO reference vaccine strain of Mycobacterium bovis BCG Danish targets 83% of all nonessential genes and was made publicly available via the BCCM/ITM Mycobacteria Collection. This resource will speed up Mycobacterium research (e.g., drug resistance research and vaccine development) and paves the way to similar genome-wide mutant collections in other strains of the Mycobacterium tuberculosis complex. The stretch to a full collection of mutants in all nonessential genes is now much shorter, with just 17% remaining genes to be targeted using gene-by-gene approaches, for which highly effective methods have recently also been described.
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Affiliation(s)
- Katlyn Borgers
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Kristof Vandewalle
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Annelies Van Hecke
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Gitte Michielsen
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Evelyn Plets
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Loes van Schie
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Sandrine Vanmarcke
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | | | - Nele Festjens
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Nico Callewaert
- Center for Medical Biotechnology, VIB-Ghent University, Ghent, Belgium
- Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
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5
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Borgers K, Vandewalle K, Festjens N, Callewaert N. A guide to Mycobacterium mutagenesis. FEBS J 2019; 286:3757-3774. [PMID: 31419030 DOI: 10.1111/febs.15041] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 07/05/2019] [Accepted: 08/12/2019] [Indexed: 12/18/2022]
Abstract
The genus Mycobacterium includes several pathogens that cause severe disease in humans, like Mycobacterium tuberculosis (M. tb), the infectious agent causing tuberculosis. Genetic tools to engineer mycobacterial genomes, in a targeted or random fashion, have provided opportunities to investigate M. tb infection and pathogenesis. Furthermore, they have allowed the identification and validation of potential targets for the diagnosis, prevention, and treatment of tuberculosis. This review describes the various methods that are available for the generation of mutants in Mycobacterium species, focusing specifically on tools for altering slow-growing mycobacteria from the M. tb complex. Among others, it incorporates the recent new molecular biological technologies (e.g. ORBIT) to rapidly and/or genome-wide comprehensively obtain targeted mutants in mycobacteria. As such, this review can be used as a guide to select the appropriate genetic tools to generate mycobacterial mutants of interest, which can be used as tools to aid understanding of M. tb infection or to help developing TB intervention strategies.
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Affiliation(s)
- Katlyn Borgers
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
| | - Kristof Vandewalle
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
| | - Nele Festjens
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
| | - Nico Callewaert
- VIB-UGhent Center for Medical Biotechnology, Belgium.,Department of Biochemistry and Microbiology, Ghent University, Belgium
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Sun B, Yang J, Yang S, Ye RD, Chen D, Jiang Y. A CRISPR-Cpf1-Assisted Non-Homologous End Joining Genome Editing System of Mycobacterium smegmatis. Biotechnol J 2018; 13:e1700588. [PMID: 30039929 DOI: 10.1002/biot.201700588] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 06/21/2018] [Indexed: 01/24/2023]
Abstract
Mycobacterium smegmatis is an important model strain of Mycobacterium for scientific study because it is non-pathogenic and grows rapidly. However, research is limited by the low efficiency and time-consuming nature of existing genome editing tools. Although the Streptococcus pyogenes CRISPR-Cas9 system is widely used in bacterial genome editing, it cannot be introduced into M. smegmatis because of its toxicity. The authors test 14 different Cas effector proteins in M. smegmatis. Cas9 (TdCas9_m) from Treponema denticola, Cas9 (NmCas9) from Neisseria meningitidis, and Corynebacterium glutamicum codon-optimized Cpf1 (FnCpf1_cg) from Francisella tularensis do not affect cell growth. The numbers of transformant plasmids expressing TdCas9_m, NmCas9, or FnCpf1_cg, and guide RNAs (gRNA) targeting ku(MSMEG_5580), ligD(MSMEG_6301), pta(MSMEG_0783), or ackA(MSMEG_0784) decreases by about 10-, 10-, or 100-fold, respectively, compared with plasmids expressing only the Cas effector proteins. Non-homologous end joining (NHEJ) is detected only in the CRISPR-FnCpf1_cg system. The one-plasmid-based, CRISPR-FnCpf1-assisted NHEJ system enables N iterative rounds of genome editing in 7N + 2 days, with an editing efficiency up to 70%; thus, this system should greatly reduce the necessary genome manipulation time for M. smegmatis.
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Affiliation(s)
- Bingbing Sun
- School of Pharmacy, Shanghai Jiaotong University, Shanghai 200240, China.,Shanghai Institute of Pharmaceutical Industry, China State Institute of Pharmaceutical Industry, Shanghai 201203, China
| | - Junjie Yang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Sheng Yang
- School of Pharmacy, Shanghai Jiaotong University, Shanghai 200240, China
| | - Richard D Ye
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China
| | - Daijie Chen
- School of Pharmacy, Shanghai Jiaotong University, Shanghai 200240, China
| | - Yu Jiang
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.,Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing 211816, China
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PhoPR Positively Regulates whiB3 Expression in Response to Low pH in Pathogenic Mycobacteria. J Bacteriol 2018; 200:JB.00766-17. [PMID: 29378889 DOI: 10.1128/jb.00766-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Accepted: 01/22/2018] [Indexed: 01/18/2023] Open
Abstract
During infection, Mycobacterium tuberculosis colonizes macrophages or necrotic granulomas, in which low pH is one of the major challenges. The PhoPR two-component regulatory system and the cytosolic redox sensor WhiB3 both play important roles in the response to low pH by M. tuberculosis However, whether close association exists between PhoPR and WhiB3 remains unclear. In this study, the positive regulation of whiB3 by PhoPR in mycobacteria was characterized. We observed that the expression patterns of the whiB3 gene under acidic conditions are different among mycobacterial species, suggesting that the regulation of whiB3 differs among mycobacteria. A sequence analysis of the whiB3 promoters (whiB3p) from M. tuberculosis and two closely related species, namely, M. marinum and M. smegmatis, showed that the whiB3p regions from M. tuberculosis and M. marinum contain a new type of PhoP box that is absent in the M. smegmatiswhiB3p Direct binding of PhoP to whiB3p from M. tuberculosis and M. marinum but not that from M. smegmatis was validated by in vitro protein-DNA binding assays. The direct activation of whiB3 by PhoPR under acidic conditions was further verified by reverse transcription-quantitative PCR (qRT-PCR) analysis in M. marinum Moreover, mutating the residues important for the phosphorylation pathway of PhoPR in M. marinum abolished the activation of whiB3 expression by PhoPR under acidic conditions, suggesting that low pH triggers the phosphorylation of PhoPR, which in turn activates the transcription of whiB3 Since the PhoP box was only identified in whiB3p of pathogenic mycobacteria, we suggest that the PhoPR-whiB3 regulatory pathway may have evolved to facilitate mycobacterial infection.IMPORTANCE The low pH in macrophages is an important barrier for infection by microbes. The PhoPR two-component regulatory system is required for the response to low pH and plays a role in redox homeostasis in Mycobacterium tuberculosis WhiB3, a cytosolic redox-sensing transcriptional regulator, is also involved in these processes. However, there is no direct evidence to demonstrate the regulation of WhiB3 by PhoPR. In this study, we found that PhoPR directly activates whiB3 expression in response to low pH. An atypical PhoP box in the whiB3 promoters has been identified and is only found in pathogenic mycobacteria, which suggests that the PhoPR-whiB3 regulatory pathway may facilitate mycobacterial infection. This study provides novel information for further characterization of the PhoPR regulon.
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Ji X, Wang Y, Li J, Rong Q, Chen X, Zhang Y, Liu X, Li B, Zhao H. Application of FLP-FRT System to Construct Unmarked Deletion in Helicobacter pylori and Functional Study of Gene hp0788 in Pathogenesis. Front Microbiol 2017; 8:2357. [PMID: 29238332 PMCID: PMC5712585 DOI: 10.3389/fmicb.2017.02357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 11/15/2017] [Indexed: 12/21/2022] Open
Abstract
Helicobacter pylori is a Gram-negative, microaerophilic bacterium associated with human gastric diseases. Further investigations on virulence genes are still required to clarify the pathogenic mechanism of H. pylori and the heterogeneous problem of infection. In order to develop an efficient and accurate method to study gene functions in H. pylori pathogenesis, an unmarked deletion method for both a single gene and a large fragment was established based on the FLP-FRT recombination system. Using this method, the gene hp0788, encoding an outer membrane protein (HofF), was deleted. Deletion of hp0788 did not affect growth or motility of H. pylori, but reduced the adherence of the bacteria to gastric epithelial cells. The apoptosis of GES-1 cells caused by H. pylori infection was also reduced by the defection of hp0788. These suggest that hp0788 takes part in the bacterium-host interaction and plays an important role in H. pylori infection. Furthermore, a large genomic fragment deletion from hp0541 to hp0547 in cag pathogenicity island was also successfully achieved using FLP-FRT method. The innovative application of the FLP-FRT recombination system in H. pylori to construct unmarked deletion would provide a helpful tool for further function research of putative pathogenic genes and contribute to the understanding of H. pylori pathogenesis.
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Affiliation(s)
- Xiaofei Ji
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, China
| | - Ying Wang
- Central Laboratory, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, China
| | - Jiaojiao Li
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, China
| | - Qianyu Rong
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, China
| | - Xingxing Chen
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, China
| | - Ying Zhang
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, China
| | - Xiaoning Liu
- Central Laboratory, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, China
| | - Boqing Li
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, China
| | - Huilin Zhao
- Department of Pathogenic Biology, School of Basic Medical Sciences, Binzhou Medical University, Yantai, China
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Hu Y, Wang Z, Feng L, Chen Z, Mao C, Zhu Y, Chen S. σ(E) -dependent activation of RbpA controls transcription of the furA-katG operon in response to oxidative stress in mycobacteria. Mol Microbiol 2016; 102:107-20. [PMID: 27353316 DOI: 10.1111/mmi.13449] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2016] [Indexed: 01/08/2023]
Abstract
Mycobacterium tuberculosis adopts various strategies to cope with oxidative stress during infection. Transcriptional regulators, including σ factors, make important contributions to this stress response, but how these proteins cooperate with each other is largely unknown. In this study, the role of RbpA and its cooperation with σ factors in response to oxidative stress are investigated. Knock down expression of rbpA in Mycobacterium smegmatis attenuated bacterial survival in the presence of H2 O2 . Additionally, transcription of the rbpA gene was induced by H2 O2 in a σ(E) -dependent manner. After induction, RbpA interacts with the principal sigma factor, σ(A) , to control the transcription of furA-katG operon, which encodes an H2 O2 scavenging enzyme. Moreover, this regulation is responsible for the role of σ(E) in oxidative response because bacterial survival was attenuated and transcription of the furA-katG operon was down-regulated with H2 O2 treatment in sigE deletion mutant (ΔsigE), and over-expression of RbpA in ΔsigE strain restored all of these phenotypes. Taken together, our study first illustrated a mechanism for σ(E) in response to oxidative stress through regulation of rbpA transcription. This study was also the first to demonstrate that RbpA is required for the full response to oxidative stress by cooperating with the principal σ(A) .
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Affiliation(s)
- Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Zhongwei Wang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, 10086, China
| | - Lipeng Feng
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, 10086, China
| | - Zhenkang Chen
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, 10086, China
| | - Chunyou Mao
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, 10086, China
| | - Yan Zhu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, 10086, China
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.
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Pavlenok M, Niederweis M. Hetero-oligomeric MspA pores in Mycobacterium smegmatis. FEMS Microbiol Lett 2016; 363:fnw046. [PMID: 26912121 DOI: 10.1093/femsle/fnw046] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/20/2016] [Indexed: 12/22/2022] Open
Abstract
The porin MspA of Mycobacterium smegmatis is a biological nanopore used for DNA sequencing. The octameric MspA pore can be isolated from M. smegmatis in milligram quantities, is extremely stable against denaturation and rapidly inserts into lipid membranes. Here, we show that MspA pores composed of different Msp subunits are formed in M. smegmatis and that hetero-oligomers of different Msp monomers increase the heterogeneity of MspA pores designed for DNA sequencing. To improve the quality of preparations of mutant MspA proteins, all four msp genes were deleted from the M. smegmatis genome after insertion of an inducible porin gene from M. tuberculosis. In the msp quadruple mutant M. smegmatis ML712 no Msp porins were detected and mutant MspA proteins were produced at wild-type levels. Lipid bilayer experiments demonstrated that MspA pores isolated from ML712 formed functional channels and had a narrower conductance distribution than pores purified from M. smegmatis with background msp expression. Thus, the M. smegmatis msp quadruple mutant improves the homogeneity of MspA pores designed for DNA sequencing and might also facilitate the identification and functional characterization of other mycobacterial pore proteins.
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Affiliation(s)
- Mikhail Pavlenok
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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11
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Tan Y, Xu Z, Tao J, Ni J, Zhao W, Lu J, Yao YF. A SIRT4-like auto ADP-ribosyltransferase is essential for the environmental growth of Mycobacterium smegmatis. Acta Biochim Biophys Sin (Shanghai) 2016; 48:145-52. [PMID: 26685303 DOI: 10.1093/abbs/gmv121] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 09/26/2015] [Indexed: 01/12/2023] Open
Abstract
SIRT family proteins are highly conserved both in the structure and function among all the organisms, and are involved in gene silencing, DNA damage repair, cell growth and metabolism. Here, a SIRT4 homologue MSMEG_4620 was identified and characterized in Mycobacterium smegmatis. MSMEG_4620 exhibits deacetylase activity that can be activated by fatty acids. Interestingly, MSMEG_4620 also possesses auto ADP-ribosylation activity. MSMEG_4620 is modified on arginine residues as revealed by a chemical stability assay. Moreover, the auto ADP-ribosylation activity of MSMEG_4620 was found to be enhanced by ferric ion. Notably, the SIRT4 homologues are widely distributed in the genomes of environmental mycobacterial species instead of pathogenic mycobacterial species. When MSMEG_4620 was deleted in M. smegmatis, the mutant strain showed a growth defect in 7H9 minimal medium compared with the parental strain. Taken together, these results provided the characteristics of a SIRT4 homologue in prokaryotes and implicated its critical roles in the growth of environmental mycobacterial species.
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Affiliation(s)
- Yongcong Tan
- Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Zhihong Xu
- Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jing Tao
- Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jinjing Ni
- Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wei Zhao
- Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Jie Lu
- Department of Infectious Diseases, Shanghai Ruijin Hospital, Shanghai 200025, China
| | - Yu-Feng Yao
- Laboratory of Bacterial Pathogenesis, Department of Microbiology and Immunology, Institutes of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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12
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Croux C, Nguyen NPT, Lee J, Raynaud C, Saint-Prix F, Gonzalez-Pajuelo M, Meynial-Salles I, Soucaille P. Construction of a restriction-less, marker-less mutant useful for functional genomic and metabolic engineering of the biofuel producer Clostridium acetobutylicum. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:23. [PMID: 26839586 PMCID: PMC4736252 DOI: 10.1186/s13068-016-0432-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 01/07/2016] [Indexed: 05/20/2023]
Abstract
BACKGROUND Clostridium acetobutylicum is a gram-positive, spore-forming, anaerobic bacterium capable of converting various sugars and polysaccharides into solvents (acetone, butanol, and ethanol). The sequencing of its genome has prompted new approaches to genetic analysis, functional genomics, and metabolic engineering to develop industrial strains for the production of biofuels and bulk chemicals. RESULTS The method used in this paper to knock-out or knock-in genes in C. acetobutylicum combines the use of an antibiotic-resistance gene for the deletion or replacement of the target gene, the subsequent elimination of the antibiotic-resistance gene with the flippase recombinase system from Saccharomyces cerevisiae, and a C. acetobutylicum strain that lacks upp, which encodes uracil phosphoribosyl-transferase, for subsequent use as a counter-selectable marker. A replicative vector containing (1) a pIMP13 origin of replication from Bacillus subtilis that is functional in Clostridia, (2) a replacement cassette consisting of an antibiotic resistance gene (MLS (R) ) flanked by two FRT sequences, and (3) two sequences homologous to selected regions around target DNA sequence was first constructed. This vector was successfully used to consecutively delete the Cac824I restriction endonuclease encoding gene (CA_C1502) and the upp gene (CA_C2879) in the C. acetobutylicum ATCC824 chromosome. The resulting C. acetobutylicum Δcac1502Δupp strain is marker-less, readily transformable without any previous plasmid methylation and can serve as the host for the "marker-less" genetic exchange system. The third gene, CA_C3535, shown in this study to encode for a type II restriction enzyme (Cac824II) that recognizes the CTGAAG sequence, was deleted using an upp/5-FU counter-selection strategy to improve the efficiency of the method. The restriction-less marker-less strain and the method was successfully used to delete two genes (ctfAB) on the pSOL1 megaplasmid and one gene (ldhA) on the chromosome to get strains no longer producing acetone or l-lactate. CONCLUSIONS The restriction-less, marker-less strain described in this study, as well as the maker-less genetic exchange coupled with positive selection, will be useful for functional genomic studies and for the development of industrial strains for the production of biofuels and bulk chemicals.
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Affiliation(s)
- Christian Croux
- />LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
| | | | - Jieun Lee
- />College of Life Sciences and Biotechnology, Korea University, Seoul, South Korea
| | | | - Florence Saint-Prix
- />LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
| | - Maria Gonzalez-Pajuelo
- />LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
| | | | - Philippe Soucaille
- />LISBP, INSA, University of Toulouse, 135 Avenue de Rangueil, 31077 Toulouse Cedex, France
- />Metabolic Explorer, Saint-Beauzire, France
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FLP-FRT-based method to obtain unmarked deletions of CHU_3237 (porU) and large genomic fragments of Cytophaga hutchinsonii. Appl Environ Microbiol 2014; 80:6037-45. [PMID: 25063660 DOI: 10.1128/aem.01785-14] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Cytophaga hutchinsonii is a widely distributed cellulolytic bacterium in the phylum Bacteroidetes. It can digest crystalline cellulose rapidly without free cellulases or cellulosomes. The mechanism of its cellulose utilization remains a mystery. We developed an efficient method based on a linear DNA double-crossover and FLP-FRT recombination system to obtain unmarked deletions of both single genes and large genomic fragments in C. hutchinsonii. Unmarked deletion of CHU_3237 (porU), an ortholog of the C-terminal signal peptidase of a type IX secretion system (T9SS), resulted in defects in colony spreading, cellulose degradation, and protein secretion, indicating that it is a component of the T9SS and that T9SS plays an important role in cellulose degradation by C. hutchinsonii. Furthermore, deletions of four large genomic fragments were obtained using our method, and the sizes of the excised fragments varied from 9 to 19 kb, spanning from 6 to 22 genes. The customized FLP-FRT method provides an efficient tool for more rapid progress in the cellulose degradation mechanism and other physiological aspects of C. hutchinsonii.
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14
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Jeßberger N, Lu Y, Amon J, Titgemeyer F, Sonnewald S, Reid S, Burkovski A. Nitrogen starvation-induced transcriptome alterations and influence of transcription regulator mutants in Mycobacterium smegmatis. BMC Res Notes 2013; 6:482. [PMID: 24266988 PMCID: PMC4222082 DOI: 10.1186/1756-0500-6-482] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 11/18/2013] [Indexed: 11/16/2022] Open
Abstract
Background As other bacteria, Mycobacterium smegmatis needs adaption mechanisms to cope with changing nitrogen sources and to survive situations of nitrogen starvation. In the study presented here, transcriptome analyses were used to characterize the response of the bacterium to nitrogen starvation and to elucidate the role of specific transcriptional regulators. Results In response to nitrogen deprivation, a general starvation response is induced in M. smegmatis. This includes changes in the transcription of several hundred genes encoding e.g. transport proteins, proteins involved in nitrogen metabolism and regulation, energy generation and protein turnover. The specific nitrogen-related changes at the transcriptional level depend mainly on the presence of GlnR, while the AmtR protein controls only a small number of genes. Conclusions M. smegmatis is able to metabolize a number of different nitrogen sources and nitrogen control in M. smegmatis is similar to control mechanisms characterized in streptomycetes, while the master regulator of nitrogen control in corynebacteria, AmtR, is plays a minor role in this regulatory network.
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Affiliation(s)
- Nadja Jeßberger
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
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Shenkerman Y, Elharar Y, Vishkautzan M, Gur E. Efficient and simple generation of unmarked gene deletions in Mycobacterium smegmatis. Gene 2013; 533:374-8. [PMID: 24100088 DOI: 10.1016/j.gene.2013.09.082] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 09/15/2013] [Accepted: 09/23/2013] [Indexed: 10/26/2022]
Abstract
Genetic research in molecular laboratories relies heavily on directed mutagenesis and gene deletion techniques. In mycobacteria, however, genetic analysis is often hindered by difficulties in the preparation of deletion mutants. Indeed, in comparison to the allelic exchange systems available for the study of other common model organisms, such as Saccharomyces cerevisiae and Escherichia coli, mycobacterial gene disruption systems suffer from low mutant isolation success rates, mostly due to inefficient homologous recombination and a high degree of non-specific recombination. Here, we present a gene deletion system that combines efficient homologous recombination with advanced screening of mutants. This novel methodology allows for gene disruption in three consecutive steps. The first step relies on the use of phage Che9c recombineering proteins for directed insertion into the chromosome of a linear DNA fragment that encodes GFP and confers hygromycin resistance. In the second step, GFP positive and hygromycin resistant colonies are selected, and in the last step, the gfp-hyg cassette is excised from the chromosome, thus resulting in the formation of an unmarked deletion. We provide a detailed gene deletion methodology and demonstrate the use of this genetic system by deleting the prcSBA operon of Mycobacterium smegmatis.
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Affiliation(s)
- Yael Shenkerman
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
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16
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Abstract
Copper resistance mechanisms are crucial for many pathogenic bacteria, including Mycobacterium tuberculosis, during infection because the innate immune system utilizes copper ions to kill bacterial intruders. Despite several studies detailing responses of mycobacteria to copper, the pathways by which copper ions cross the mycobacterial cell envelope are unknown. Deletion of porin genes in Mycobacterium smegmatis leads to a severe growth defect on trace copper medium but simultaneously increases tolerance for copper at elevated concentrations, indicating that porins mediate copper uptake across the outer membrane. Heterologous expression of the mycobacterial porin gene mspA reduced growth of M. tuberculosis in the presence of 2.5 μM copper by 40% and completely suppressed growth at 15 μM copper, while wild-type M. tuberculosis reached its normal cell density at that copper concentration. Moreover, the polyamine spermine, a known inhibitor of porin activity in Gram-negative bacteria, enhanced tolerance of M. tuberculosis for copper, suggesting that copper ions utilize endogenous outer membrane channel proteins of M. tuberculosis to gain access to interior cellular compartments. In summary, these findings highlight the outer membrane as the first barrier against copper ions and the role of porins in mediating copper uptake in M. smegmatis and M. tuberculosis.
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17
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Characterization of the MSMEG_2631 gene (mmp) encoding a multidrug and toxic compound extrusion (MATE) family protein in Mycobacterium smegmatis and exploration of its polyspecific nature using biolog phenotype microarray. J Bacteriol 2013; 195:1610-21. [PMID: 23292779 DOI: 10.1128/jb.01724-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Mycobacterium, multidrug efflux pumps can be associated with intrinsic drug resistance. Comparison of putative mycobacterial transport genes revealed a single annotated open reading frame (ORF) for a multidrug and toxic compound extrusion (MATE) family efflux pump in all sequenced mycobacteria except Mycobacterium leprae. Since MATE efflux pumps function as multidrug efflux pumps by conferring resistance to structurally diverse antibiotics and DNA-damaging chemicals, we studied this gene (MSMEG_2631) in M. smegmatis mc(2)155 and determined that it encodes a MATE efflux system that contributes to intrinsic resistance of Mycobacterium. We propose that the MSMEG_2631 gene be named mmp, for mycobacterial MATE protein. Biolog Phenotype MicroArray data indicated that mmp deletion increased susceptibility for phleomycin, bleomycin, capreomycin, amikacin, kanamycin, cetylpyridinium chloride, and several sulfa drugs. MSMEG_2619 (efpA) and MSMEG_3563 mask the effect of mmp deletion due to overlapping efflux capabilities. We present evidence that mmp is a part of an MSMEG_2626-2628-2629-2630-2631 operon regulated by a strong constitutive promoter, initiated from a single transcription start site. All together, our results show that M. smegmatis constitutively encodes an Na(+)-dependent MATE multidrug efflux pump from mmp in an operon with putative genes encoding proteins for apparently unrelated functions.
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18
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Kateete DP, Katabazi FA, Okeng A, Okee M, Musinguzi C, Asiimwe BB, Kyobe S, Asiimwe J, Boom WH, Joloba ML. Rhomboids of Mycobacteria: characterization using an aarA mutant of Providencia stuartii and gene deletion in Mycobacterium smegmatis. PLoS One 2012; 7:e45741. [PMID: 23029216 PMCID: PMC3448690 DOI: 10.1371/journal.pone.0045741] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 08/24/2012] [Indexed: 01/07/2023] Open
Abstract
Background Rhomboids are ubiquitous proteins with unknown roles in mycobacteria. However, bioinformatics suggested putative roles in DNA replication pathways and metabolite transport. Here, mycobacterial rhomboid-encoding genes were characterized; first, using the Providencia stuartii null-rhomboid mutant and then deleted from Mycobacterium smegmatis for additional insight in mycobacteria. Methodology/Principal Findings Using in silico analysis we identified in M. tuberculosis genome the genes encoding two putative rhomboid proteins; Rv0110 (referred to as “rhomboid protease 1”) and Rv1337 (“rhomboid protease 2”). Genes encoding orthologs of these proteins are widely represented in all mycobacterial species. When transformed into P. stuartii null-rhomboid mutant (ΔaarA), genes encoding mycobacterial orthologs of “rhomboid protease 2” fully restored AarA activity (AarA is the rhomboid protein of P. stuartii). However, most genes encoding mycobacterial “rhomboid protease 1” orthologs did not. Furthermore, upon gene deletion in M. smegmatis, the ΔMSMEG_4904 single mutant (which lost the gene encoding MSMEG_4904, orthologous to Rv1337, “rhomboid protease 2”) formed the least biofilms and was also more susceptible to ciprofloxacin and novobiocin, antimicrobials that inhibit DNA gyrase. However, the ΔMSMEG_5036 single mutant (which lost the gene encoding MSMEG_5036, orthologous to Rv0110, “rhomboid protease 1”) was not as susceptible. Surprisingly, the double rhomboid mutant ΔMSMEG_4904–ΔMSMEG_5036 (which lost genes encoding both homologs) was also not as susceptible suggesting compensatory effects following deletion of both rhomboid-encoding genes. Indeed, transforming the double mutant with a plasmid encoding MSMEG_5036 produced phenotypes of the ΔMSMEG_4904 single mutant (i.e. susceptibility to ciprofloxacin and novobiocin). Conclusions/Significance Mycobacterial rhomboid-encoding genes exhibit differences in complementing aarA whereby it's only genes encoding “rhomboid protease 2” orthologs that fully restore AarA activity. Additionally, gene deletion data suggests inhibition of DNA gyrase by MSMEG_4904; however, the ameliorated effect in the double mutant suggests occurrence of compensatory mechanisms following deletion of genes encoding both rhomboids.
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Affiliation(s)
- David Patrick Kateete
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
| | - Fred Ashaba Katabazi
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
| | - Alfred Okeng
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
| | - Moses Okee
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
| | - Conrad Musinguzi
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
| | - Benon Byamugisha Asiimwe
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
| | - Samuel Kyobe
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
| | - Jeniffer Asiimwe
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
- College of Veterinary Medicine, Animal Resources and Biosecurity (CoVAB), Makerere University, Kampala, Uganda
| | - W. Henry Boom
- Tuberculosis Research Unit (TBRU), Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Moses Lutaakome Joloba
- Department of Medical Microbiology, School of Biomedical Sciences, Makerere University College of Health Sciences (MakCHS), Kampala, Uganda
- Tuberculosis Research Unit (TBRU), Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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19
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Eibauer M, Hoffmann C, Plitzko JM, Baumeister W, Nickell S, Engelhardt H. Unraveling the structure of membrane proteins in situ by transfer function corrected cryo-electron tomography. J Struct Biol 2012; 180:488-96. [PMID: 23000705 DOI: 10.1016/j.jsb.2012.09.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 08/30/2012] [Accepted: 09/03/2012] [Indexed: 01/05/2023]
Abstract
Cryo-electron tomography in combination with subtomogram averaging allows to investigate the structure of protein assemblies in their natural environment in a close to live state. To make full use of the structural information contained in tomograms it is necessary to analyze the contrast transfer function (CTF) of projections and to restore the phases of higher spatial frequencies. CTF correction is however hampered by the difficulty of determining the actual defocus values from tilt series data, which is due to the low signal-to-noise ratio of electron micrographs. In this study, an extended acquisition scheme is introduced that enables an independent CTF determination. Two high-dose images are recorded along the tilt axis on both sides of each projection, which allow an accurate determination of the defocus values of these images. These values are used to calculate the CTF for each image of the tilt series. We applied this scheme to the mycobacterial outer membrane protein MspA reconstituted in lipid vesicles and tested several variants of CTF estimation in combination with subtomogram averaging and correction of the modulation transfer function (MTF). The 3D electron density map of MspA was compared with a structure previously determined by X-ray crystallography. We were able to demonstrate that structural information up to a resolution of 16.8Å can be recovered using our CTF correction approach, whereas the uncorrected 3D map had a resolution of only 26.2Å.
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20
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Du QL, Fan XY, Mao JX, Xie JP. [Progression on genetic knockout tools in Mycobacterium]. YI CHUAN = HEREDITAS 2012; 34:857-62. [PMID: 22805211 DOI: 10.3724/sp.j.1005.2012.00857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Pathogenic mycobacteria were and remain a heavy burden to public health. Unfortunately, genetic manipulation including knockout technologies of Mycobacterium is difficult compared with other traditional model organisms. To overcome this obstacle, achievements in Mycobacterium knockout technologies were summarized, including delivery vector, sequence-specific recombination system, as well as the recently developed recombinogenic engineering and its application. The future for this tool innovation is also addressed.
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Affiliation(s)
- Qin-Lin Du
- Institute of Modern Biopharmaceuticals, State Key Laboratory Breeding Base of Eco-Environment and Bio-Resource of the Three Gorges Area, School of Life Sciences, Southwest University, Chongqing 400715, China.
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21
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Song H, Huff J, Janik K, Walter K, Keller C, Ehlers S, Bossmann SH, Niederweis M. Expression of the ompATb operon accelerates ammonia secretion and adaptation of Mycobacterium tuberculosis to acidic environments. Mol Microbiol 2011; 80:900-18. [PMID: 21410778 DOI: 10.1111/j.1365-2958.2011.07619.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Homeostasis of intracellular pH is a trait critical for survival of Mycobacterium tuberculosis in macrophages. However, mechanisms by which M. tuberculosis adapts to acidic environments are poorly understood. In this study, we analysed the physiological functions of OmpATb, a surface-accessible protein of M. tuberculosis. OmpATb did not complement the permeability defects of a Mycobacterium smegmatis porin mutant to glucose, serine and glycerol, in contrast to the porin MspA. Uptake rates of these solutes were unchanged in an ompATb operon mutant of M. tuberculosis indicating that OmpATb is not a general porin. Chemical analysis of low-pH culture filtrates showed that the proteins encoded by the ompATb operon are involved in generating a rapid ammonia burst, which neutralized medium pH and preceded exponential growth of M. tuberculosis. Addition of ammonia accelerated growth of the ompATb operon mutant demonstrating that ammonia secretion is indeed a mechanism by which M. tuberculosis neutralizes acidic environments. Infection experiments revealed that the ompATb operon was not required for full virulence in mice suggesting that M. tuberculosis has multiple mechanisms of resisting phagosomal acidification. Taken together, these results show that the ompATb operon is necessary for rapid ammonia secretion and adaptation of M. tuberculosis to acidic environments in vitro but not in mice.
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Affiliation(s)
- Houhui Song
- Department of Microbiology, University of Alabama at Birmingham, 609 Bevill Biomedical Research Building, 845 19th Street South, Birmingham, AL 35294, USA
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22
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Huff J, Czyz A, Landick R, Niederweis M. Taking phage integration to the next level as a genetic tool for mycobacteria. Gene 2010; 468:8-19. [PMID: 20692326 DOI: 10.1016/j.gene.2010.07.012] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Revised: 07/26/2010] [Accepted: 07/27/2010] [Indexed: 11/25/2022]
Abstract
Genes must be stably integrated into bacterial chromosomes for complementation of gene deletion mutants in animal infection experiments or to express antigens in vaccine strains. However, with currently available vectors it is cumbersome to create multiple, stable, unmarked chromosomal integrations in mycobacteria. Here, we have constructed a novel integration vector for mycobacteria that enables expression of genes from a cassette protected from transcriptional interference by bi-directional transcriptional terminators proven to be highly efficient in in vitro transcription termination assays. Removal of the integrase gene by a site-specific recombinase, easily identifiable by loss of a backbone reporter gene, stabilizes the integration cassette and makes this vector ideally suitable for infection experiments. This integration vector can be easily adapted to different mycobacteriophage attachment sites (attB) due to its modular design. Integration of a gfp expression cassette at the L5, Giles and Ms6 attB sites in the chromosomes of Mycobacterium smegmatis and Mycobacterium tuberculosis yielded identical gfp expression levels, indicating that none of these sites are compromised for gene expression. The copy number of pAL5000-based extrachromosomal plasmids is 23 in M. smegmatis as determined by quantitative real-time PCR and accounts for the previously observed drastic reduction of gene expression upon integration of plasmids into the chromosome of mycobacteria. Gfp expression and fluorescence of M. smegmatis and M. tuberculosis strains with multiple integrations of gfp increased concomitantly with the copy number demonstrating that these vectors can be used to generate stronger phenotypes and/or to analyze several genes simultaneously in vivo.
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Affiliation(s)
- Jason Huff
- Department of Microbiology, University of Alabama at Birmingham, 609 Bevill Biomedical Research Building, 845 19th Street South, Birmingham, AL 35294, USA
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Cascioferro A, Boldrin F, Serafini A, Provvedi R, Palù G, Manganelli R. Xer site-specific recombination, an efficient tool to introduce unmarked deletions into mycobacteria. Appl Environ Microbiol 2010; 76:5312-6. [PMID: 20543044 PMCID: PMC2916470 DOI: 10.1128/aem.00382-10] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 06/01/2010] [Indexed: 02/01/2023] Open
Abstract
Genetic manipulation of mycobacteria still represents a serious challenge due to the lack of tools and selection markers. In this report, we describe the development of an intrinsically unstable excisable cassette for introduction of unmarked mutations in both Mycobacterium smegmatis and Mycobacterium tuberculosis.
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Affiliation(s)
- Alessandro Cascioferro
- Department of Histology, Microbiology, and Medical Biotechnologies, Department of Biology, University of Padua, Padua, Italy
| | - Francesca Boldrin
- Department of Histology, Microbiology, and Medical Biotechnologies, Department of Biology, University of Padua, Padua, Italy
| | - Agnese Serafini
- Department of Histology, Microbiology, and Medical Biotechnologies, Department of Biology, University of Padua, Padua, Italy
| | - Roberta Provvedi
- Department of Histology, Microbiology, and Medical Biotechnologies, Department of Biology, University of Padua, Padua, Italy
| | - Giorgio Palù
- Department of Histology, Microbiology, and Medical Biotechnologies, Department of Biology, University of Padua, Padua, Italy
| | - Riccardo Manganelli
- Department of Histology, Microbiology, and Medical Biotechnologies, Department of Biology, University of Padua, Padua, Italy
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Development and application of a PCR-targeted gene disruption method for studying CelR function in Thermobifida fusca. Appl Environ Microbiol 2010; 76:2098-106. [PMID: 20097808 DOI: 10.1128/aem.02626-09] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thermobifida fusca is a high-G+C-content, thermophilic, Gram-positive soil actinobacterium with high cellulolytic activity. In T. fusca, CelR is thought to act as the primary regulator of cellulase gene expression by binding to a 14-bp inverted repeat [5'-(T)GGGAGCGCTCCC(A)] that is upstream of many known cellulase genes. Previously, the ability to study the roles and regulation of cellulase genes in T. fusca has been limited largely by a lack of established genetic engineering methods for T. fusca. In this study, we developed an efficient procedure for creating precise chromosomal gene disruptions and demonstrated this procedure by generating a celR deletion strain. The celR deletion strain was then characterized using measurements for growth behavior, cellulase activity, and gene expression. The celR deletion strain of T. fusca exhibited a severely crippled growth phenotype with a prolonged lag phase and decreased cell yields for growth on both glucose and cellobiose. While the maximum endoglucanase activity and cellulase activity were not significantly changed, the endoglucanase activity and cellulase activity per cell were highly elevated. Measurements of mRNA transcript levels in both the celR deletion strain and the wild-type strain indicated that the CelR protein potentially acts as a repressor for some genes and as an activator for other genes. Overall, we established and demonstrated a method for manipulating chromosomal DNA in T. fusca that can be used to study the cellulolytic capabilities of this organism. Components of this method may be useful in developing genetic engineering methods for other currently intractable organisms.
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Sharbati S, Schramm K, Rempel S, Wang H, Andrich R, Tykiel V, Kunisch R, Lewin A. Characterisation of porin genes from Mycobacterium fortuitum and their impact on growth. BMC Microbiol 2009; 9:31. [PMID: 19203364 PMCID: PMC2651896 DOI: 10.1186/1471-2180-9-31] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 02/09/2009] [Indexed: 01/25/2023] Open
Abstract
Background Highly pathogenic mycobacteria like Mycobacterium tuberculosis are characterised by their slow growth and their ability to reside and multiply in the very hostile phagosomal environment and a correlation between the growth rate of mycobacteria and their pathogenicity has been hypothesised. Here, porin genes from M. fortuitum were cloned and characterised to address their impact on the growth rate of fast-growing and pathogenic mycobacteria. Results Two genes encoding porins orthologous to MspA from M. smegmatis, porM1 and porM2, were cloned from M. fortuitum strains, which were originally isolated from human patients. Both porin genes were at least partially able to complement the mutations of a M. smegmatis mutant strain lacking the genes mspA and mspC with respect to the growth rate. PorM1 and porM2 were present in different strains of M. fortuitum including the type strain. Comparative expression analysis of porM genes revealed divergent porin expression among analysed M. fortuitum strains. Repression of the expression of porins by antisense technique decreased the growth rates of different M. fortuitum. The effects of over-expression of porM1 as well as porM2 varied depending on the strain and the concentration of antibiotic added to the medium and indicated that PorM1 and PorM2 enhance the growth of M. fortuitum strains, but also the diffusion of the antibiotic kanamycin into the cells. Conclusion This study demonstrates the important role of porin expression in growth as well as antibiotic susceptibility of the opportunistic bacterium M. fortuitum.
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Affiliation(s)
- Soroush Sharbati
- Freie Universität Berlin, Institute of Veterinary Biochemistry, Berlin, Germany.
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Abstract
The identification of essential genes is of major importance to mycobacterial research, and a number of essential genes have been identified in mycobacteria, however confirming essentiality is not straightforward, as deletion of essential genes results in a lethal phenotype. In this chapter, protocols are described that can be used to confirm gene essentiality using gene switching, following the construction of a delinquent strain. Because deletion mutants cannot be created for essential genes, a second gene copy is introduced via an integrating vector, which allows the chromosomal gene copy to be deleted. The integrated vector can then be replaced using the gene switching method; where no transformants are obtained, essentiality is confirmed. This technique can also be used to confirm functionality of gene homologues and to easily identify essential operon members.
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Affiliation(s)
- Amanda Claire Brown
- Institute of Cell and Molecular Science, Barts and the London, Queen Mary's School of Medicine and Dentistry, 4 Newark Street, Whitechapel, London E1 2AA, UK.
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Abstract
Site-specific recombinases such as the Saccharomyces cerevisiae Flp and the P1 phage Cre proteins have been increasingly used for the construction of unmarked deletions in bacteria. Both systems consist of an antibiotic resistance gene flanked by recognition sites in direct orientation and a curable plasmid for temporary expression of the respective recombinase gene. In this chapter, we describe strategies and methods of how to use sequence-specific recombination mediated by Flp and Cre to construct mutants of Mycobacterium smegmatis, Mycobacterium bovis BCG, and Mycobacterium tuberculosis.
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Affiliation(s)
- Houhui Song
- Department of Microbiology, University of Alabama at Birmingham, Alabama 35294, USA
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Nitrogen control in Mycobacterium smegmatis: nitrogen-dependent expression of ammonium transport and assimilation proteins depends on the OmpR-type regulator GlnR. J Bacteriol 2008; 190:7108-16. [PMID: 18689485 DOI: 10.1128/jb.00855-08] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effect of nitrogen regulation on the level of transcriptional control has been investigated in a variety of bacteria, such as Bacillus subtilis, Corynebacterium glutamicum, Escherichia coli, and Streptomyces coelicolor; however, until now there have been no data for mycobacteria. In this study, we found that the OmpR-type regulator protein GlnR controls nitrogen-dependent transcription regulation in Mycobacterium smegmatis. Based on RNA hybridization experiments with a wild-type strain and a corresponding mutant strain, real-time reverse transcription-PCR analyses, and DNA binding studies using cell extract and purified protein, the glnA (msmeg_4290) gene, which codes for glutamine synthetase, and the amtB (msmeg_2425) and amt1 (msmeg_6259) genes, which encode ammonium permeases, are controlled by GlnR. Furthermore, since glnK (msmeg_2426), encoding a PII-type signal transduction protein, and glnD (msmeg_2427), coding for a putative uridylyltransferase, are in an operon together with amtB, these genes are part of the GlnR regulon as well. The GlnR protein binds specifically to the corresponding promoter sequences and functions as an activator of transcription when cells are subjected to nitrogen starvation.
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Dani RK, Kang M, Kalita M, Smith PE, Bossmann SH, Chikan V. MspA Porin-Gold Nanoparticle Assemblies: Enhanced Binding through a Controlled Cysteine Mutation. NANO LETTERS 2008; 8:1229-1236. [PMID: 18318505 DOI: 10.1021/nl072658h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
In this study, the interactions of two gold nanoparticles of different sizes (average diameters of 3.7 +/- 2.6 and 17 +/- 3 nm) with octameric mycobacterial porin A from Mycobacterium smegmatis (MspA) and a mutant of MspA featuring a cysteine mutation in position 126 (Q126C) are investigated. From the observation of enhanced photoluminescence quenching, it is inferred that the presence of eight cysteines in the MspA Q126C mutant significantly enhances the binding of selected small gold nanoparticles within the inner pore of MspA. The large gold nanoparticle/porin complex shows photoluminescence enhancement, which is expected since the larger nanoparticles cannot dock within the homopore of MspA due to size exclusion. In addition to the fluorescence experiments, observation of energy transfer from the small gold nanoparticles to the MspA shows the close proximity of the small gold nanoparticles with the porin. Interestingly, the energy transfer of the large nanoparticle/MspA complex is completely missing. From high-performance liquid chromatography data, the estimated binding constants for small Au@MspA, large Au@MspA, small Au@MspAcys, and large Au@MspAcys are 1.3 x 10 (9), 2.22 x 10 (10), > 10 (12) (irreversible), and 1.7 x 10 (10), respectively.
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Affiliation(s)
- Raj Kumar Dani
- Department of Chemistry, Kansas State University, Manhattan, KS 66506-3701, USA
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30
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Fehér T, Papp B, Pal C, Pósfai G. Systematic genome reductions: theoretical and experimental approaches. Chem Rev 2007; 107:3498-513. [PMID: 17636890 DOI: 10.1021/cr0683111] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tamas Fehér
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary
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31
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Song H, Niederweis M. Functional expression of the Flp recombinase in Mycobacterium bovis BCG. Gene 2007; 399:112-9. [PMID: 17590537 PMCID: PMC1987385 DOI: 10.1016/j.gene.2007.05.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 05/03/2007] [Accepted: 05/04/2007] [Indexed: 11/18/2022]
Abstract
Mycobacteria contain a large number of redundant genes whose functions are difficult to analyze in mutants because there are only two efficient antibiotic resistance genes available for allelic exchange experiments. Sequence-specific recombinbases such as the Flp recombinase can be used to excise resistance markers. Expression of the flp(e) gene from Saccharomyces cerevisiae is functional for this purpose in fast-growing Mycobacterium smegmatis but not in slow-growing mycobacteria such as M. bovis BCG or M. tuberculosis. We synthesized the flp(m) gene by adapting the codon usage to that preferred by M. tuberculosis. This increased the G+C content from 38% to 61%. Using the synthetic flp(m) gene, the frequency of removal of FRT-hyg-FRT cassette from the chromosome by the Flp recombinase was increased by more than 100-fold in M. smegmatis. In addition, 40% of all clones of M. bovis BCG had lost the hyg resistance cassette after transient expression of the flp(m) gene. Sequencing of the chromosomal DNA showed that excision of the FRT-hyg-FRT cassette by Flp was specific. These results show that the flp(m) encoded Flp recombinase is not only an improved genetic tool for M. smegmatis, but can also be used in slow growing mycobacteria such as M. tuberculosis for constructing unmarked mutations. Other more sophisticated applications in mycobacterial genetics would also profit from the improved Flp/FRT system.
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Affiliation(s)
| | - Michael Niederweis
- * For correspondence: Phone: +1-205-996-2711, Fax: +1-205-934-9256, E-Mail:
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Wolschendorf F, Mahfoud M, Niederweis M. Porins are required for uptake of phosphates by Mycobacterium smegmatis. J Bacteriol 2007; 189:2435-42. [PMID: 17209034 PMCID: PMC1899398 DOI: 10.1128/jb.01600-06] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phosphorus is an essential nutrient, but how phosphates cross the mycobacterial cell wall is unknown. Phosphatase activity in whole cells of Mycobacterium smegmatis was significantly lower than that in lysed cells, indicating that access to the substrate was restricted. The loss of the outer membrane (OM) porin MspA also reduced the phosphatase activity in whole cells compared to that in lysed cells. A similar result was obtained for M. smegmatis that overexpressed endogenous alkaline phosphatase, indicating that PhoA is not a surface protein, contrary to a previous report. The uptake of phosphate by a mutant lacking the porins MspA and MspC was twofold lower than that by wild-type M. smegmatis. Strikingly, the loss of these porins resulted in a severe growth defect of M. smegmatis on low-phosphate plates. We concluded that the OM of M. smegmatis represents a permeability barrier for phosphates and that Msp porins are the only OM channels for the diffusion of phosphate in M. smegmatis. However, phosphate diffusion through Msp pores is rather inefficient as shown by the 10-fold lower permeability of M. smegmatis for phosphate compared to that for glucose. This is likely due to the negative charges in the constriction zone of Msp porins. The phosphatase activity in whole cells of Mycobacterium bovis BCG was significantly less than that in lysed cells, indicating a similar uptake pathway for phosphates in slow-growing mycobacteria. However, porins that could mediate the diffusion of phosphates across the OM of M. bovis BCG and Mycobacterium tuberculosis are unknown.
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Affiliation(s)
- Frank Wolschendorf
- Department of Microbiology, University of Alabama at Birmingham, Mail Box 24, 609 Bevill Biomedical Research Building, 845 19th Street South, Birmingham, AL 35294, USA
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Weider M, Machnik A, Klebl F, Sauer N. Vhr1p, a New Transcription Factor from Budding Yeast, Regulates Biotin-dependent Expression of VHT1 and BIO5. J Biol Chem 2006; 281:13513-13524. [PMID: 16533810 DOI: 10.1074/jbc.m512158200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcription of the Saccharomyces cerevisiae vitamin H transporter gene VHT1 is enhanced by low extracellular biotin. Here we present the identification and characterization of Vhr1p as a transcriptional regulator of VHT1 (VHR1 (YIL056w); VHT1 regulator 1) and the identification of the cis-regulatory target sequences for Vhr1p in two yeast promoters. VHR1 was identified in a complementation screening of mutagenized yeast cells that had lost the capacity to express the gene of the green fluorescent protein (GFP) from the VHT1 promoter. Deltavhr1 deletion mutants fail to induce VHT1 on low biotin concentrations. In yeast one-hybrid analyses performed with fusions of Vhr1p N-terminal and C-terminal fragments to the Gal4p activation domain or to the Gal4p DNA-binding domain, the Vhr1p N terminus mediated biotin-dependent DNA binding, and the Vhr1p C terminus triggered biotin-dependent transcriptional activation. The analyzed Vhr1p N-terminal fragment has previously been described as a domain of unknown function (DUF352). Deletion and linker scanning analyses of the VHT1 promoter revealed the palindromic 18-nucleotide sequence AATCA-N8-TGAYT as the vitamin H-responsive element. This sequence was identified also in the BIO5 promoter that is also transcriptionally activated on low biotin concentrations. Bio5p mediates the transport of 7-keto-8-aminopelargonic acid across the yeast plasma membrane, a compound that is used as a precursor in biotin biosynthesis. Deltavhr1 deletion mutants fail to induce BIO5 on low biotin concentrations. The presented data characterize Vhr1p as an essential component of the biotin-dependent signal transduction cascade in yeast.
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Affiliation(s)
- Matthias Weider
- Molekulare Pflanzenphysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany
| | - Agnes Machnik
- Molekulare Pflanzenphysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany
| | - Franz Klebl
- Molekulare Pflanzenphysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany
| | - Norbert Sauer
- Molekulare Pflanzenphysiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany.
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Stephan J, Bender J, Wolschendorf F, Hoffmann C, Roth E, Mailänder C, Engelhardt H, Niederweis M. The growth rate of Mycobacterium smegmatis depends on sufficient porin-mediated influx of nutrients. Mol Microbiol 2006; 58:714-30. [PMID: 16238622 DOI: 10.1111/j.1365-2958.2005.04878.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mycobacteria have a unique outer membrane (OM) that is thicker than any other known biological membrane. Nutrients cross this permeability barrier by diffusion through porins. MspA is the major porin of Mycobacterium smegmatis. In this study we showed that three paralogues of MspA, namely MspB, MspC and MspD are also porins. However, only the mspA and mspC genes were expressed in the wild-type strain. None of the single deletion mutants displayed a significant OM permeability defect except for the mspA mutant. Deletion of the mspA gene caused activation of transcription of mspB and/or mspD in three independent strains by unknown chromosomal mutations. It is concluded that mspB and mspD provide backup porins for M. smegmatis. This also indicated that a minimal porin-mediated OM permeability is essential for survival of M. smegmatis. Electron microscopy in combination with quantitative image analysis of protein gels revealed that the number of pores per cell dropped from 2400 to 800 and 150 for the DeltamspA and DeltamspA DeltamspC mutant (ML10) respectively. The very low number of pores correlated well with the at least 20-fold lower channel activity of detergent extracts of the ML10 strain and its 15- and 75-fold lower permeability to nutrient molecules such as serine and glucose respectively. The amount of Msp porin and the OM permeability of the triple porin mutant lacking mspA, mspC and mspD was not altered. The growth rate of M. smegmatis dropped drastically with its porin-mediated OM permeability in contrast to porin mutants of Escherichia coli. These results show that porin-mediated influx of nutrients is a major determinant of the growth rate of M. smegmatis.
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Affiliation(s)
- Joachim Stephan
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstrasse 5, D-91058 Erlangen, Germany
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Sharbati-Tehrani S, Stephan J, Holland G, Appel B, Niederweis M, Lewin A. Porins limit the intracellular persistence of Mycobacterium smegmatis. MICROBIOLOGY-SGM 2005; 151:2403-2410. [PMID: 16000730 DOI: 10.1099/mic.0.27969-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The genus Mycobacterium comprises highly pathogenic as well as opportunistic or apathogenic species exhibiting a great variability with respect to their ability to persist or multiply within monocytic host cells. The impact of the permeability of the mycobacterial outer membrane on intracellular persistence was studied. For this purpose, a Mycobacterium smegmatis mutant with a deletion of the major porin gene mspA and a second mutant lacking mspA and the homologous porin gene mspC were used. Deletion of mspA together with mspC significantly enhanced intracellular persistence in murine bone marrow macrophages, the mouse macrophage cell line J774A.1 and Acanthamoeba castellanii. Complementation of mspA in the porin mutant strains resulted in restoration of the wild-type phenotype with respect to intracellular persistence. This is the first report to show that the deletion of porins of mycobacteria results in improved persistence in eukaryotic cells, demonstrating that the intracellular persistence of M. smegmatis depends upon the permeability of the outer membrane.
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Affiliation(s)
| | - Joachim Stephan
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Gudrun Holland
- Robert Koch-Institut, Nordufer 20, 13353 Berlin, Germany
| | - Bernd Appel
- Robert Koch-Institut, Nordufer 20, 13353 Berlin, Germany
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
- Lehrstuhl für Mikrobiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Astrid Lewin
- Robert Koch-Institut, Nordufer 20, 13353 Berlin, Germany
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Current awareness on yeast. Yeast 2005; 22:745-52. [PMID: 16106592 DOI: 10.1002/yea.1165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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