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Ng WL, Rego EH. A nucleoid-associated protein is involved in the emergence of antibiotic resistance by promoting the frequent exchange of the replicative DNA polymerase in Mycobacterium smegmatis. mSphere 2024; 9:e0012224. [PMID: 38591887 PMCID: PMC11237743 DOI: 10.1128/msphere.00122-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Accepted: 03/16/2024] [Indexed: 04/10/2024] Open
Abstract
Antibiotic resistance in Mycobacterium tuberculosis exclusively originates from chromosomal mutations, either during normal DNA replication or under stress, when the expression of error-prone DNA polymerases increases to repair damaged DNA. To bypass DNA lesions and catalyze error-prone DNA synthesis, translesion polymerases must be able to access the DNA, temporarily replacing the high-fidelity replicative polymerase. The mechanisms that govern polymerase exchange are not well understood, especially in mycobacteria. Here, using a suite of quantitative fluorescence imaging techniques, we discover that in Mycobacterium smegmatis, as in other bacterial species, the replicative polymerase, DnaE1, exchanges at a timescale much faster than that of DNA replication. Interestingly, this fast exchange rate depends on an actinobacteria-specific nucleoid-associated protein (NAP), Lsr2. In cells missing lsr2, DnaE1 exchanges less frequently, and the chromosome is replicated more faithfully. Additionally, in conditions that damage DNA, cells lacking lsr2 load the complex needed to bypass DNA lesions less effectively and, consistently, replicate with higher fidelity but exhibit growth defects. Together, our results show that Lsr2 promotes dynamic flexibility of the mycobacterial replisome, which is critical for robust cell growth and lesion repair in conditions that damage DNA. IMPORTANCE Unlike many other pathogens, Mycobacterium tuberculosis has limited ability for horizontal gene transfer, a major mechanism for developing antibiotic resistance. Thus, the mechanisms that facilitate chromosomal mutagenesis are of particular importance in mycobacteria. Here, we show that Lsr2, a nucleoid-associated protein, has a novel role in DNA replication and mutagenesis in the model mycobacterium Mycobacterium smegmatis. We find that Lsr2 promotes the fast exchange rate of the replicative DNA polymerase, DnaE1, at the replication fork and is important for the effective loading of the DnaE2-ImuA'-ImuB translesion complex. Without lsr2, M. smegmatis replicates its chromosome more faithfully and acquires resistance to rifampin at a lower rate, but at the cost of impaired survival to DNA damaging agents. Together, our work establishes Lsr2 as a potential factor in the emergence of mycobacterial antibiotic resistance.
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Affiliation(s)
- Wei L Ng
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - E Hesper Rego
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
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2
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Gerges E, Rodríguez-Ordoñez MDP, Durand N, Herrmann JL, Crémazy F. Lsr2, a pleiotropic regulator at the core of the infectious strategy of Mycobacterium abscessus. Microbiol Spectr 2024; 12:e0352823. [PMID: 38353553 PMCID: PMC10913753 DOI: 10.1128/spectrum.03528-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 01/22/2024] [Indexed: 03/06/2024] Open
Abstract
Mycobacterium abscessus is a non-tuberculous mycobacterium, causing lung infections in cystic fibrosis patients. During pulmonary infection, M. abscessus switches from smooth (Mabs-S) to rough (Mabs-R) morphotypes, the latter being hyper-virulent. Previously, we isolated the lsr2 gene as differentially expressed during S-to-R transition. lsr2 encodes a pleiotropic transcription factor that falls under the superfamily of nucleoid-associated proteins. Here, we used two functional genomic methods, RNA-seq and chromatin immunoprecipitation-sequencing (ChIP-seq), to elucidate the molecular role of Lsr2 in the pathobiology of M. abscessus. Transcriptomic analysis shows that Lsr2 differentially regulates gene expression across both morphotypes, most of which are involved in several key cellular processes of M. abscessus, including host adaptation and antibiotic resistance. These results were confirmed through quantitative real-time PCR, as well as by minimum inhibitory concentration tests and infection tests on macrophages in the presence of antibiotics. ChIP-seq analysis revealed that Lsr2 extensively binds the M. abscessus genome at AT-rich sequences and appears to form long domains that participate in the repression of its target genes. Unexpectedly, the genomic distribution of Lsr2 revealed no distinctions between Mabs-S and Mabs-R, implying more intricate mechanisms at play for achieving target selectivity.IMPORTANCELsr2 is a crucial transcription factor and chromosome organizer involved in intracellular growth and virulence in the smooth and rough morphotypes of Mycobacterium abscessus. Using RNA-seq and chromatin immunoprecipitation-sequencing (ChIP-seq), we investigated the molecular role of Lsr2 in gene expression regulation along with its distribution on M. abscessus genome. Our study demonstrates the pleiotropic regulatory role of Lsr2, regulating the expression of many genes coordinating essential cellular and molecular processes in both morphotypes. In addition, we have elucidated the role of Lsr2 in antibiotic resistance both in vitro and in vivo, where lsr2 mutant strains display heightened sensitivity to antibiotics. Through ChIP-seq, we reported the widespread distribution of Lsr2 on M. abscessus genome, revealing a direct repressive effect due to its extensive binding on promoters or coding sequences of its targets. This study unveils the significant regulatory role of Lsr2, intricately intertwined with its function in shaping the organization of the M. abscessus genome.
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Affiliation(s)
- Elias Gerges
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
| | - María del Pilar Rodríguez-Ordoñez
- Université Paris-Saclay, Université d’Evry, Laboratoire Européen de Recherche pour la Polyarthrite rhumatoïde-Genhotel, Evry, France
| | - Nicolas Durand
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
| | - Jean-Louis Herrmann
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
- APHP, GHU Paris-Saclay, Hôpital Raymond Poincaré, Service de Microbiologie, Garches, France
| | - Frédéric Crémazy
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, Montigny-Le-Bretonneux, France
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Gerges E, Herrmann JL, Crémazy F. [Lsr2: A Nucleoid Associated Protein (NAP) and a transcription factor in mycobacteria]. Med Sci (Paris) 2024; 40:154-160. [PMID: 38411423 DOI: 10.1051/medsci/2023218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/28/2024] Open
Abstract
Lsr2, a small protein mainly found in actinobacteria, plays a crucial role in the virulence and adaptation of mycobacteria to environmental conditions. As a member of the nucleoid-associated protein (NAPs) superfamily, Lsr2 influences DNA organization by facilitating the formation of chromosomal loops in vitro and, therefore, may be a major player in the three-dimensional folding of the genome. Additionally, Lsr2 also acts as a transcription factor, regulating the expression of numerous genes responsible for coordinating a myriad of cellular and molecular processes essential for the actinobacteria. Similar to the H-NS protein, its ortholog in enterobacteria, its role in transcriptional repression likely relies on oligomerization, rigidifying, and bridging of DNA, thereby disrupting RNA polymerase recruitment as well as the elongation of RNA transcripts.
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Affiliation(s)
- Elias Gerges
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, 78180 Montigny-Le-Bretonneux, France
| | - Jean-Louis Herrmann
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, 78180 Montigny-Le-Bretonneux, France
| | - Frédéric Crémazy
- Université Paris-Saclay, UVSQ, Inserm, Infection et inflammation, 78180 Montigny-Le-Bretonneux, France
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Ng WL, Rego EH. A nucleoid-associated protein is involved in the emergence of antibiotic resistance by promoting the frequent exchange of the replicative DNA polymerase in M. smegmatis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.06.12.544663. [PMID: 38260554 PMCID: PMC10802252 DOI: 10.1101/2023.06.12.544663] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Antibiotic resistance in M. tuberculosis exclusively originates from chromosomal mutations, either during normal DNA replication or under stress, when the expression of error-prone DNA polymerases increases to repair damaged DNA. To bypass DNA lesions and catalyze error-prone DNA synthesis, translesion polymerases must be able to access the DNA, temporarily replacing the high-fidelity replicative polymerase. The mechanisms that govern polymerase exchange are not well understood, especially in mycobacteria. Here, using a suite of quantitative fluorescence imaging techniques, we discover that, as in other bacterial species, in M. smegmatis, the replicative polymerase, DnaE1, exchanges at a timescale much faster than that of DNA replication. Interestingly, this fast exchange rate depends on an actinobacteria-specific nucleoid-associated protein (NAP), Lsr2. In cells missing lsr2, DnaE1 exchanges less frequently, and the chromosome is replicated more faithfully. Additionally, in conditions that damage DNA, cells lacking lsr2 load the complex needed to bypass DNA lesions less effectively and, consistently, replicate with higher fidelity but exhibit growth defects. Together, our results show that Lsr2 promotes dynamic flexibility of the mycobacterial replisome, which is critical for robust cell growth and lesion repair in conditions that damage DNA.
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Affiliation(s)
- Wei L. Ng
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06519
| | - E. Hesper Rego
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06519
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5
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Born SEM, Reichlen MJ, Bartek IL, Benoit JB, Frank DN, Voskuil MI. Population heterogeneity in Mycobacterium smegmatis and Mycobacterium abscessus. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001402. [PMID: 37862100 PMCID: PMC10634367 DOI: 10.1099/mic.0.001402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 10/06/2023] [Indexed: 10/21/2023]
Abstract
Bacteria use population heterogeneity, the presence of more than one phenotypic variant in a clonal population, to endure diverse environmental challenges - a 'bet-hedging' strategy. Phenotypic variants have been described in many bacteria, but the phenomenon is not well-understood in mycobacteria, including the environmental factors that influence heterogeneity. Here, we describe three reproducible morphological variants in M. smegmatis - smooth, rough, and an intermediate morphotype that predominated under typical laboratory conditions. M. abscessus has two recognized morphotypes, smooth and rough. Interestingly, M. tuberculosis exists in only a rough form. The shift from smooth to rough in both M. smegmatis and M. abscessus was observed over time in extended static culture, however the frequency of the rough morphotype was high in pellicle preparations compared to planktonic culture, suggesting a role for an aggregated microenvironment in the shift to the rough form. Differences in growth rate, biofilm formation, cell wall composition, and drug tolerance were noted among M. smegmatis and M. abscessus variants. Deletion of the global regulator lsr2 shifted the M. smegmatis intermediate morphotype to a smooth form but did not fully phenocopy the naturally generated smooth morphotype, indicating Lsr2 is likely downstream of the initiating regulatory cascade that controls these morphotypes. Rough forms typically correlate with higher invasiveness and worse outcomes during infection and our findings indicate the shift to this rough form is promoted by aggregation. Our findings suggest that mycobacterial population heterogeneity, reflected in colony morphotypes, is a reproducible, programmed phenomenon that plays a role in adaptation to unique environments and this heterogeneity may influence infection progression and response to treatment.
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Affiliation(s)
- Sarah E. M. Born
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Matthew J. Reichlen
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Iona L. Bartek
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jeanne B. Benoit
- Division of Infectious Diseases, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Daniel N. Frank
- Division of Infectious Diseases, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Martin I. Voskuil
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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6
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Dulberger CL, Guerrero-Bustamante CA, Owen SV, Wilson S, Wuo MG, Garlena RA, Serpa LA, Russell DA, Zhu J, Braunecker BJ, Squyres GR, Baym M, Kiessling LL, Garner EC, Rubin EJ, Hatfull GF. Mycobacterial nucleoid-associated protein Lsr2 is required for productive mycobacteriophage infection. Nat Microbiol 2023; 8:695-710. [PMID: 36823286 PMCID: PMC10066036 DOI: 10.1038/s41564-023-01333-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 01/23/2023] [Indexed: 02/25/2023]
Abstract
Mycobacteriophages are a diverse group of viruses infecting Mycobacterium with substantial therapeutic potential. However, as this potential becomes realized, the molecular details of phage infection and mechanisms of resistance remain ill-defined. Here we use live-cell fluorescence microscopy to visualize the spatiotemporal dynamics of mycobacteriophage infection in single cells and populations, showing that infection is dependent on the host nucleoid-associated Lsr2 protein. Mycobacteriophages preferentially adsorb at Mycobacterium smegmatis sites of new cell wall synthesis and following DNA injection, Lsr2 reorganizes away from host replication foci to establish zones of phage DNA replication (ZOPR). Cells lacking Lsr2 proceed through to cell lysis when infected but fail to generate consecutive phage bursts that trigger epidemic spread of phage particles to neighbouring cells. Many mycobacteriophages code for their own Lsr2-related proteins, and although their roles are unknown, they do not rescue the loss of host Lsr2.
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Affiliation(s)
- Charles L Dulberger
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | | | - Siân V Owen
- Department of Biomedical Informatics and Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Sean Wilson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Michael G Wuo
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Rebecca A Garlena
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lexi A Serpa
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Daniel A Russell
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Junhao Zhu
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Ben J Braunecker
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Georgia R Squyres
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Michael Baym
- Department of Biomedical Informatics and Laboratory of Systems Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Laura L Kiessling
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
| | - Eric J Rubin
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, MA, USA.
| | - Graham F Hatfull
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
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7
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Wu CY, Diaz S, Ellis A, Jones R, Pucheu-Haston C. Cutaneous Mycobacterium goodii infection in an immunocompetent cat in Louisiana: clinical presentation, molecular identification, antimicrobial susceptibility and management. JFMS Open Rep 2022; 8:20551169221090442. [PMID: 35462863 PMCID: PMC9021483 DOI: 10.1177/20551169221090442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Case summary A 9-year-old spayed female domestic shorthair cat was presented to a referral hospital for management of recurring non-healing ulcerations and a subcutaneous mass on the ventral abdomen. Prior treatment included antibiotics (cefovecin followed by clindamycin), wound cleaning and surgical debulking, but the ulcerations and mass recurred 1 month after surgical removal. At this point, the cat was started on doxycycline and pradofloxacin and referred for further work-up. The culture of skin biopsy specimens obtained at the time of referral revealed a population of bacterial colonies with two distinctly different phenotypes. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and 16S rRNA gene sequencing identified both colonies as Mycobacterium goodii. A diagnosis of a cutaneous infection of rapidly growing mycobacteria was made, and treatment with oral pradofloxacin and doxycycline was initiated. The ulcerations resolved within 4 months, and the subcutaneous mass gradually decreased in size until it was no longer palpable, even 4 months after the cessation of antibiotics. Relevance and novel information This is the second reported feline cutaneous M goodii infection in North America. The organism was not visualized on histopathology but was successfully cultured from tissue obtained by skin punch biopsy. A phenotypic switching phenomenon affecting the susceptibility results was suspected, possibly explaining the presence of phenotypically different but genetically identical strains. This case highlights the importance of submitting aseptically obtained tissue, fluid or fine-needle aspirates for culture and species identification, as well as histopathology, when infection with higher bacteria, such as rapidly growing mycobacteria, is suspected.
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Affiliation(s)
- Chi-Yen Wu
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
| | - Sandra Diaz
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH, USA
| | | | - Rebekah Jones
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN, USA
| | - Cherie Pucheu-Haston
- Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA, USA
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Elimination of PknL and MSMEG_4242 in Mycobacterium smegmatis alters the character of the outer cell envelope and selects for mutations in Lsr2. ACTA ACUST UNITED AC 2021; 7:100060. [PMID: 34485766 PMCID: PMC8408660 DOI: 10.1016/j.tcsw.2021.100060] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 08/12/2021] [Accepted: 08/13/2021] [Indexed: 11/23/2022]
Abstract
Elimination of pknL and adjacent gene MSMEG_4242 in M. smegmatis produces rough & smooth colonies. All smooth colony mutants have inactivated lsr2 genes. Inactivated lsr2 leads to high expression of MSMEG_4727 and increased synthesis of LOS. Smooth mutants don’t form biofilms, have longer bacilli and increased sliding motility. Rough strains deleted for pknL and MSMEG_4242 form biofilms but have aberrant sliding motility. We propose a phosphorylation cascade of PknB phosphorylating PknL that then phosphorylates Lsr2.
Four serine/threonine kinases are present in all mycobacteria: PknA, PknB, PknG and PknL. PknA and PknB are essential for growth and replication, PknG regulates metabolism, but little is known about PknL. Inactivation of pknL and adjacent regulator MSMEG_4242 in rough colony M. smegmatis mc2155 produced both smooth and rough colonies. Upon restreaking rough colonies, smooth colonies appeared at a frequency of ~ 1/250. Smooth mutants did not form biofilms, showed increased sliding motility and anomalous lipids on thin-layer chromatography, identified by mass spectrometry as lipooligosaccharides and perhaps also glycopeptidolipids. RNA-seq and Sanger sequencing revealed that all smooth mutants had inactivated lsr2 genes due to mutations and different IS1096 insertions. When complemented with lsr2, the colonies became rough, anomalous lipids disappeared and sliding motility decreased. Smooth mutants showed increased expression of IS1096 transposase TnpA and MSMEG_4727, which encodes a protein similar to PKS5. When MSMEG_4727 was deleted, smooth pknL/MSMEG_4242/lsr2 mutants reverted to rough, formed good biofilms, their motility decreased slightly and their anomalous lipids disappeared. Rough delpknL/del4242 mutants formed poor biofilms and showed decreased, aberrant sliding motility and both phenotypes were complemented with the two deleted genes. Inactivation of lsr2 changes colony morphology from rough to smooth, augments sliding motility and increases expression of MSMEG_4727 and other enzymes synthesizing lipooligosaccharides, apparently preventing biofilm formation. Similar morphological phase changes occur in other mycobacteria, likely reflecting environmental adaptations. PknL and MSMEG_4242 regulate lipid components of the outer cell envelope and their absence selects for lsr2 inactivation. A regulatory, phosphorylation cascade model is proposed.
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9
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Pan L, Chen J, Ren S, Shen H, Rong B, Liu W, Yang Z. Complete genome sequence of Mycobacterium Mya-zh01, an endophytic bacterium, promotes plant growth and seed germination isolated from flower stalk of Doritaenopsis. Arch Microbiol 2020; 202:1965-1976. [DOI: 10.1007/s00203-020-01924-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 05/16/2020] [Accepted: 05/26/2020] [Indexed: 11/27/2022]
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Suarez CA, Franceschelli JJ, Tasselli SE, Morbidoni HR. Weirdo19ES is a novel singleton mycobacteriophage that selects for glycolipid deficient phage-resistant M. smegmatis mutants. PLoS One 2020; 15:e0231881. [PMID: 32357186 PMCID: PMC7194413 DOI: 10.1371/journal.pone.0231881] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 04/02/2020] [Indexed: 11/23/2022] Open
Abstract
The sequencing and bioinformatics analysis of bacteriophages infecting mycobacteria has yielded a large amount of information on their evolution, including that on their environmental propagation on other genera such as Gordonia, closely related to Mycobacterium. However, little is known on mycobacteriophages cell biology such as the nature of their receptor(s) or their replication cycle. As part of our on-going screening for novel mycobacteriophages, we herein report the isolation and genome bioinformatics analysis of Weirdo19ES, a singleton Siphoviridae temperate mycobacteriophage with a 70.19% GC content. Nucleotide and protein sequence comparison to actinobacteriophage databases revealed that Weirdo19ES shows low homology to Gordonia phage Ruthy and mycobacteriophages falling in clusters Q and G and to singleton DS6A.Weirdo19ES also displays uncommon features such as a very short Lysin A gene (with only one enzymatic domain) and two putative HNH endonucleases. Mycobacterium smegmatis mutants resistant to Weirdo19ES are cross- resistant to I3. In agreement with that phenotype, analysis of cell envelope of those mutants showed that Weirdo19ES shares receptors with the transducing mycobacteriophage I3.This singleton mycobacteriophage adds up to the uncommonness of local mycobacteriophages previously isolated by our group and helps understanding the nature of mycobacteriophage receptors.
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Affiliation(s)
- Cristian Alejandro Suarez
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Jorgelina Judith Franceschelli
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Sabrina Emilse Tasselli
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Héctor Ricardo Morbidoni
- Laboratorio de Microbiología Molecular, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
- * E-mail:
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11
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Johansen MD, Herrmann JL, Kremer L. Non-tuberculous mycobacteria and the rise of Mycobacterium abscessus. Nat Rev Microbiol 2020; 18:392-407. [PMID: 32086501 DOI: 10.1038/s41579-020-0331-1] [Citation(s) in RCA: 399] [Impact Index Per Article: 99.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/15/2020] [Indexed: 12/17/2022]
Abstract
Infections caused by non-tuberculous mycobacteria (NTM) are increasing globally and are notoriously difficult to treat due to intrinsic resistance of these bacteria to many common antibiotics. NTM are diverse and ubiquitous in the environment, with only a few species causing serious and often opportunistic infections in humans, including Mycobacterium abscessus. This rapidly growing mycobacterium is one of the most commonly identified NTM species responsible for severe respiratory, skin and mucosal infections in humans. It is often regarded as one of the most antibiotic-resistant mycobacteria, leaving us with few therapeutic options. In this Review, we cover the proposed infection process of M. abscessus, its virulence factors and host interactions and highlight the commonalities and differences of M. abscessus with other NTM species. Finally, we discuss drug resistance mechanisms and future therapeutic options. Taken together, this knowledge is essential to further our understanding of this overlooked and neglected global threat.
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Affiliation(s)
- Matt D Johansen
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier, France
| | - Jean-Louis Herrmann
- Université Paris-Saclay, UVSQ, Inserm, Infection et Inflammation, Montigny-Le-Bretonneux, France.,AP-HP. GHU Paris Saclay, Hôpital Raymond Poincaré, Garches, France
| | - Laurent Kremer
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique UMR 9004, Université de Montpellier, Montpellier, France. .,Inserm, Institut de Recherche en Infectiologie de Montpellier, Montpellier, France.
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12
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Samanta S, Biswas P, Banerjee A, Bose A, Siddiqui N, Nambi S, Saini DK, Visweswariah SS. A universal stress protein in Mycobacterium smegmatis sequesters the cAMP-regulated lysine acyltransferase and is essential for biofilm formation. J Biol Chem 2020; 295:1500-1516. [PMID: 31882539 PMCID: PMC7008380 DOI: 10.1074/jbc.ra119.011373] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 12/19/2019] [Indexed: 01/08/2023] Open
Abstract
Universal stress proteins (USPs) are present in many bacteria, and their expression is enhanced under various environmental stresses. We have previously identified a USP in Mycobacterium smegmatis that is a product of the msmeg_4207 gene and is a substrate for a cAMP-regulated protein lysine acyltransferase (KATms; MSMEG_5458). Here, we explored the role of this USP (USP4207) in M. smegmatis and found that its gene is present in an operon that also contains genes predicted to encode a putative tripartite tricarboxylate transporter (TTT). Transcription of the TTT-usp4207 operon was induced in the presence of citrate and tartrate, perhaps by the activity of a divergent histidine kinase-response regulator gene pair. A usp4207-deleted strain had rough colony morphology and reduced biofilm formation compared with the WT strain; however, both normal colony morphology and biofilm formation were restored in a Δusp4207Δkatms strain. We identified several proteins whose acetylation was lost in the Δkatms strain, and whose transcript levels increased in M. smegmatis biofilms along with that of USP4207, suggesting that USP4207 insulates KATms from its other substrates in the cell. We propose that USP4207 sequesters KATms from diverse substrates whose activities are down-regulated by acylation but are required for biofilm formation, thus providing a defined role for this USP in mycobacterial physiology and stress responses.
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Affiliation(s)
- Sintu Samanta
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Priyanka Biswas
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Arka Banerjee
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Avipsa Bose
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Nida Siddiqui
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Subhalaxmi Nambi
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Deepak Kumar Saini
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Sandhya S Visweswariah
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bengaluru, Karnataka 560012, India.
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Le Moigne V, Bernut A, Cortès M, Viljoen A, Dupont C, Pawlik A, Gaillard JL, Misguich F, Crémazy F, Kremer L, Herrmann JL. Lsr2 Is an Important Determinant of Intracellular Growth and Virulence in Mycobacterium abscessus. Front Microbiol 2019; 10:905. [PMID: 31114557 PMCID: PMC6503116 DOI: 10.3389/fmicb.2019.00905] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 04/09/2019] [Indexed: 12/30/2022] Open
Abstract
Mycobacterium abscessus, a pathogen responsible for severe lung infections in cystic fibrosis patients, exhibits either smooth (S) or rough (R) morphotypes. The S-to-R transition correlates with inhibition of the synthesis and/or transport of glycopeptidolipids (GPLs) and is associated with an increase of pathogenicity in animal and human hosts. Lsr2 is a small nucleoid-associated protein highly conserved in mycobacteria, including M. abscessus, and is a functional homolog of the heat-stable nucleoid-structuring protein (H-NS). It is essential in Mycobacterium tuberculosis but not in the non-pathogenic model organism Mycobacterium smegmatis. It acts as a master transcriptional regulator of multiple genes involved in virulence and immunogenicity through binding to AT-rich genomic regions. Previous transcriptomic studies, confirmed here by quantitative PCR, showed increased expression of lsr2 (MAB_0545) in R morphotypes when compared to their S counterparts, suggesting a possible role of this protein in the virulence of the R form. This was addressed by generating lsr2 knock-out mutants in both S (Δlsr2-S) and R (Δlsr2-R) variants, demonstrating that this gene is dispensable for M. abscessus growth. We show that the wild-type S variant, Δlsr2-S and Δlsr2-R strains were more sensitive to H2O2 as compared to the wild-type R variant of M. abscessus. Importantly, virulence of the Lsr2 mutants was considerably diminished in cellular models (macrophage and amoeba) as well as in infected animals (mouse and zebrafish). Collectively, these results emphasize the importance of Lsr2 in M. abscessus virulence.
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Affiliation(s)
| | - Audrey Bernut
- UMR 9004, Centre National de la Recherche Scientifique, Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, Montpellier, France
| | | | - Albertus Viljoen
- UMR 9004, Centre National de la Recherche Scientifique, Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, Montpellier, France
| | - Christian Dupont
- UMR 9004, Centre National de la Recherche Scientifique, Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, Montpellier, France
| | - Alexandre Pawlik
- Unité de Pathogénomique Mycobactérienne, Institut Pasteur, Paris, France
| | - Jean-Louis Gaillard
- 2I, UVSQ, INSERM, Université Paris-Saclay, Versailles, France.,APHP, GHU PIFO, Hôpital Raymond-Poincaré - Hôpital Ambroise-Paré, Boulogne-Billancourt, France
| | | | | | - Laurent Kremer
- UMR 9004, Centre National de la Recherche Scientifique, Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, Montpellier, France.,INSERM, Institut de Recherche en Infectiologie de Montpellier, Montpellier, France
| | - Jean-Louis Herrmann
- 2I, UVSQ, INSERM, Université Paris-Saclay, Versailles, France.,APHP, GHU PIFO, Hôpital Raymond-Poincaré - Hôpital Ambroise-Paré, Boulogne-Billancourt, France
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14
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Gutiérrez AV, Viljoen A, Ghigo E, Herrmann JL, Kremer L. Glycopeptidolipids, a Double-Edged Sword of the Mycobacterium abscessus Complex. Front Microbiol 2018; 9:1145. [PMID: 29922253 PMCID: PMC5996870 DOI: 10.3389/fmicb.2018.01145] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/14/2018] [Indexed: 01/14/2023] Open
Abstract
Mycobacterium abscessus is a rapidly-growing species causing a diverse panel of clinical manifestations, ranging from cutaneous infections to severe respiratory disease. Its unique cell wall, contributing largely to drug resistance and to pathogenicity, comprises a vast panoply of complex lipids, among which the glycopeptidolipids (GPLs) have been the focus of intense research. These lipids fulfill various important functions, from sliding motility or biofilm formation to interaction with host cells and intramacrophage trafficking. Being highly immunogenic, the induction of a strong humoral response is likely to select for rough low-GPL producers. These, in contrast to the smooth high-GPL producers, display aggregative properties, which strongly impacts upon intracellular survival. A propensity to grow as extracellular cords allows these low-GPL producing bacilli to escape the innate immune defenses. Transitioning from high-GPL to low-GPL producers implicates mutations within genes involved in biosynthesis or transport of GPL. This leads to induction of an intense pro-inflammatory response and robust and lethal infections in animal models, explaining the presence of rough isolates in patients with decreased pulmonary functions. Herein, we will discuss how, thanks to the generation of defined GPL mutants and the development of appropriate cellular and animal models to study pathogenesis, GPL contribute to M. abscessus biology and physiopathology.
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Affiliation(s)
- Ana Victoria Gutiérrez
- Centre National de la Recherche Scientifique, Institut de Recherche en Infectiologie de Montpellier, UMR 9004, Université de Montpellier, Montpellier, France.,CNRS, IRD 198, INSERM U1095, APHM, Institut Hospitalo-Universitaire Méditerranée Infection, UMR 7278, Aix-Marseille Université, Marseille, France
| | - Albertus Viljoen
- Centre National de la Recherche Scientifique, Institut de Recherche en Infectiologie de Montpellier, UMR 9004, Université de Montpellier, Montpellier, France
| | - Eric Ghigo
- CNRS, Campus Joseph Aiguier, Marseille, France
| | | | - Laurent Kremer
- Centre National de la Recherche Scientifique, Institut de Recherche en Infectiologie de Montpellier, UMR 9004, Université de Montpellier, Montpellier, France.,INSERM, IRIM, Montpellier, France
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15
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Yang Y, Thomas J, Li Y, Vilchèze C, Derbyshire KM, Jacobs WR, Ojha AK. Defining a temporal order of genetic requirements for development of mycobacterial biofilms. Mol Microbiol 2017. [PMID: 28628249 DOI: 10.1111/mmi.13734] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Most mycobacterial species spontaneously form biofilms, inducing unique growth physiologies and reducing drug sensitivity. Biofilm growth progresses through three genetically programmed stages: substratum attachment, intercellular aggregation and architecture maturation. Growth of Mycobacterium smegmatis biofilms requires multiple factors including a chaperonin (GroEL1) and a nucleoid-associated protein (Lsr2), although how their activities are linked remains unclear. Here it is shown that Lsr2 participates in intercellular aggregation, but substratum attachment of Lsr2 mutants is unaffected, thereby genetically distinguishing these developmental stages. Further, a suppressor mutation in a glycopeptidolipid synthesis gene (mps) that results in hyperaggregation of cells and fully restores the form and functions of Δlsr2 mutant biofilms was identified. Suppression by the mps mutation is specific to Δlsr2; it does not rescue the maturation-deficient biofilms of a ΔgroEL1 mutant, thereby differentiating the process of aggregation from maturation. Gene expression analysis supports a stepwise process of maturation, highlighted by temporally separated, transient inductions of iron and nitrogen import genes. Furthermore, GroEL1 activity is required for induction of nitrogen, but not iron, import genes. Together, the findings begin to define molecular checkpoints during development of mycobacterial biofilms.
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Affiliation(s)
- Yong Yang
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Joseph Thomas
- Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yunlong Li
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - Catherine Vilchèze
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Keith M Derbyshire
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY, USA
| | - William R Jacobs
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA.,Howard Hughes Medical Institute, Bronx, NY, USA
| | - Anil K Ojha
- Division of Genetics, Wadsworth Center, New York State Department of Health, Albany, NY, USA.,Department of Infectious Diseases and Microbiology, University of Pittsburgh, Pittsburgh, PA, USA
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16
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Liu Y, Wang H, Cui T, Zhou X, Jia Y, Zhang H, He ZG. NapM, a new nucleoid-associated protein, broadly regulates gene expression and affects mycobacterial resistance to anti-tuberculosis drugs. Mol Microbiol 2016; 101:167-81. [DOI: 10.1111/mmi.13383] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2016] [Indexed: 12/15/2022]
Affiliation(s)
- Yu Liu
- National Key Laboratory of Agricultural Microbiology, Department of Biological Science, College of Life Science and Technology, Huazhong Agricultural University; Wuhan 430070 China
| | - Hongyang Wang
- National Key Laboratory of Agricultural Microbiology, Department of Biological Science, College of Life Science and Technology, Huazhong Agricultural University; Wuhan 430070 China
| | - Tao Cui
- National Key Laboratory of Agricultural Microbiology, Department of Biological Science, College of Life Science and Technology, Huazhong Agricultural University; Wuhan 430070 China
| | - Xiling Zhou
- National Key Laboratory of Agricultural Microbiology, Department of Biological Science, College of Life Science and Technology, Huazhong Agricultural University; Wuhan 430070 China
| | - Yanxia Jia
- Division of Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences; Beijing 100101 China
| | - Hua Zhang
- National Key Laboratory of Agricultural Microbiology, Department of Biological Science, College of Life Science and Technology, Huazhong Agricultural University; Wuhan 430070 China
| | - Zheng-Guo He
- National Key Laboratory of Agricultural Microbiology, Department of Biological Science, College of Life Science and Technology, Huazhong Agricultural University; Wuhan 430070 China
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17
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Abstract
This article summarizes what is currently known of the structures, physiological roles, involvement in pathogenicity, and biogenesis of a variety of noncovalently bound cell envelope lipids and glycoconjugates of Mycobacterium tuberculosis and other Mycobacterium species. Topics addressed in this article include phospholipids; phosphatidylinositol mannosides; triglycerides; isoprenoids and related compounds (polyprenyl phosphate, menaquinones, carotenoids, noncarotenoid cyclic isoprenoids); acyltrehaloses (lipooligosaccharides, trehalose mono- and di-mycolates, sulfolipids, di- and poly-acyltrehaloses); mannosyl-beta-1-phosphomycoketides; glycopeptidolipids; phthiocerol dimycocerosates, para-hydroxybenzoic acids, and phenolic glycolipids; mycobactins; mycolactones; and capsular polysaccharides.
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18
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Pathogenic nontuberculous mycobacteria resist and inactivate cathelicidin: implication of a novel role for polar mycobacterial lipids. PLoS One 2015; 10:e0126994. [PMID: 25993058 PMCID: PMC4436335 DOI: 10.1371/journal.pone.0126994] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 04/09/2015] [Indexed: 12/05/2022] Open
Abstract
Nontuberculous mycobacteria (NTM) are a large group of environmental organisms with worldwide distribution, but only a relatively few are known to be pathogenic. Chronic, debilitating lung disease is the most common manifestation of NTM infection, which is often refractory to treatment. The incidence and prevalence of NTM lung disease are increasing in the United States and in many parts of the world. Hence, a more complete understanding of NTM pathogenesis will provide the foundation to develop innovative approaches to treat this recalcitrant disease. Herein, we demonstrate that several species of NTM show broad resistance to the antimicrobial peptide, cathelicidin (LL-37). Resistance to LL-37 was not significantly different between M. avium that contain serovar-specific glycopeptidolipid (GPL, M. aviumssGPL) and M. avium that do not (M. aviumΔssGPL). Similarly, M. abscessus containing non-specific GPL (M. abscessusnsGPL(+)) or lacking nsGPL (M. abscessusnsGPL(-)) remained equally resistant to LL-37. These findings would support the notion that GPL are not the components responsible for NTM resistance to LL-37. Unexpectedly, the growth of M. abscessusnsGPL(-) increased with LL-37 or scrambled LL-37 peptide in a dose-dependent fashion. We also discovered that LL-37 exposed to NTM had reduced antimicrobial activity, and initial work indicates that this is likely due to inactivation of LL-37 by lipid component(s) of the NTM cell envelope. We conclude that pathogenic NTM resist and inactivate LL-37. The mechanism by which NTM circumvent the antimicrobial activity of LL-37 remains to be determined.
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Fujiwara N, Ohara N, Ogawa M, Maeda S, Naka T, Taniguchi H, Yamamoto S, Ayata M. Glycopeptidolipid of Mycobacterium smegmatis J15cs Affects Morphology and Survival in Host Cells. PLoS One 2015; 10:e0126813. [PMID: 25970481 PMCID: PMC4430512 DOI: 10.1371/journal.pone.0126813] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 04/08/2015] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium smegmatis has been widely used as a mycobacterial infection model. Unlike the M. smegmatis mc2155 strain, M. smegmatis J15cs strain has the advantage of surviving for one week in murine macrophages. In our previous report, we clarified that the J15cs strain has deleted apolar glycopeptidolipids (GPLs) in the cell wall, which may affect its morphology and survival in host cells. In this study, the gene causing the GPL deletion in the J15cs strain was identified. The mps1-2 gene (MSMEG_0400-0402) correlated with GPL biosynthesis. The J15cs strain had 18 bps deleted in the mps1 gene compared to that of the mc2155 strain. The mps1-complemented J15cs mutant restored the expression of GPLs. Although the J15cs strain produces a rough and dry colony, the colony morphology of this mps1-complement was smooth like the mc2155 strain. The length in the mps1-complemented J15cs mutant was shortened by the expression of GPLs. In addition, the GPL-restored J15cs mutant did not survive as long as the parent J15cs strain in the murine macrophage cell line J774.1 cells. The results are direct evidence that the deletion of GPLs in the J15cs strain affects bacterial size, morphology, and survival in host cells.
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Affiliation(s)
- Nagatoshi Fujiwara
- Department of Food and Nutrition, Faculty of Contemporary Human Life Science, Tezukayama University, Nara City, Nara, Japan
- Department of Bacteriology, Osaka City University Graduate School of Medicine, Osaka City, Osaka, Japan
- * E-mail:
| | - Naoya Ohara
- Department of Oral Microbiology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama City, Okayama, Japan
| | - Midori Ogawa
- Department of Microbiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu City, Fukuoka, Japan
| | - Shinji Maeda
- Molecular Epidemiology Division, Mycobacterium Reference Center, The Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Kiyose City, Tokyo, Japan
| | - Takashi Naka
- Department of Bacteriology, Osaka City University Graduate School of Medicine, Osaka City, Osaka, Japan
- MBR Co. Ltd., Toyonaka City, Osaka, Japan
| | - Hatsumi Taniguchi
- Department of Microbiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu City, Fukuoka, Japan
| | | | - Minoru Ayata
- Department of Virology, Osaka City University Graduate School of Medicine, Osaka City, Osaka, Japan
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20
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Quadri LEN. Biosynthesis of mycobacterial lipids by polyketide synthases and beyond. Crit Rev Biochem Mol Biol 2014; 49:179-211. [DOI: 10.3109/10409238.2014.896859] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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21
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Liu J, Gordon BRG. Targeting the global regulator Lsr2 as a novel approach for anti-tuberculosis drug development. Expert Rev Anti Infect Ther 2014; 10:1049-53. [DOI: 10.1586/eri.12.86] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Klepp LI, Forrellad MA, Osella AV, Blanco FC, Stella EJ, Bianco MV, Santangelo MDLP, Sassetti C, Jackson M, Cataldi AA, Bigi F, Morbidoni HR. Impact of the deletion of the six mce operons in Mycobacterium smegmatis. Microbes Infect 2012; 14:590-9. [PMID: 22353253 PMCID: PMC3615541 DOI: 10.1016/j.micinf.2012.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/28/2011] [Accepted: 01/15/2012] [Indexed: 11/19/2022]
Abstract
The Mycobacterium smegmatis genome contains six operons designated mce (mammalian cell entry). These operons, which encode membrane and exported proteins, are highly conserved in pathogenic and non-pathogenic mycobacteria. Although the function of the Mce protein family has not yet been established in Mycobacterium smegmatis, the requirement of the mce4 operon for cholesterol utilization and uptake by Mycobacterium tuberculosis has recently been demonstrated. In this study, we report the construction of an M. smegmatis knock-out mutant deficient in the expression of all six mce operons. The consequences of these mutations were studied by analyzing physiological parameters and phenotypic traits. Differences in colony morphology, biofilm formation and aggregation in liquid cultures were observed, indicating that mce operons of M. smegmatis are implicated in the maintenance of the surface properties of the cell. Importantly, the mutant strain showed reduced cholesterol uptake when compared to the parental strain. Further cholesterol uptake studies using single mce mutant strains showed that the mutation of operon mce4 was reponsible for the cholesterol uptake failure detected in the sextuple mce mutant. This finding demonstrates that mce4operon is involved in cholesterol transport in M. smegmatis.
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Affiliation(s)
- Laura I. Klepp
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina
| | - Marina A. Forrellad
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina
| | - Ana V. Osella
- Cátedra de Microbiología, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Federico C. Blanco
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina
| | - Emma J. Stella
- Cátedra de Microbiología, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
| | - María Verónica Bianco
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina
| | - María de la Paz Santangelo
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina
| | - Cristopher Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Angel A. Cataldi
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina
| | - Fabiana Bigi
- Instituto de Biotecnología, Instituto Nacional de Tecnología Agropecuaria (INTA), Castelar, Buenos Aires, Argentina
| | - Héctor R. Morbidoni
- Cátedra de Microbiología, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Rosario, Argentina
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23
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Tatham E, Sundaram Chavadi S, Mohandas P, Edupuganti UR, Angala SK, Chatterjee D, Quadri LEN. Production of mycobacterial cell wall glycopeptidolipids requires a member of the MbtH-like protein family. BMC Microbiol 2012; 12:118. [PMID: 22726990 PMCID: PMC3537567 DOI: 10.1186/1471-2180-12-118] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Accepted: 05/07/2012] [Indexed: 12/22/2022] Open
Abstract
Background Glycopeptidolipids (GPLs) are among the major free glycolipid components of the outer membrane of several saprophytic and clinically-relevant Mycobacterium species. The architecture of GPLs is based on a constant tripeptide-amino alcohol core of nonribosomal peptide synthetase origin that is N-acylated with a 3-hydroxy/methoxy acyl chain synthesized by a polyketide synthase and further decorated with variable glycosylation patterns built from methylated and acetylated sugars. GPLs have been implicated in many aspects of mycobacterial biology, thus highlighting the significance of gaining an understanding of their biosynthesis. Our bioinformatics analysis revealed that every GPL biosynthetic gene cluster known to date contains a gene (referred herein to as gplH) encoding a member of the MbtH-like protein family. Herein, we sought to conclusively establish whether gplH was required for GPL production. Results Deletion of gplH, a gene clustered with nonribosomal peptide synthetase-encoding genes in the GPL biosynthetic gene cluster of Mycobacterium smegmatis, produced a GPL deficient mutant. Transformation of this mutant with a plasmid expressing gplH restored GPL production. Complementation was also achieved by plasmid-based constitutive expression of mbtH, a paralog of gplH found in the biosynthetic gene cluster for production of the siderophore mycobactin of M. smegmatis. Further characterization of the gplH mutant indicated that it also displayed atypical colony morphology, lack of sliding motility, altered capacity for biofilm formation, and increased drug susceptibility. Conclusions Herein, we provide evidence formally establishing that gplH is essential for GPL production in M. smegmatis. Inactivation of gplH also leads to a pleiotropic phenotype likely to arise from alterations in the cell envelope due to the lack of GPLs. While genes encoding MbtH-like proteins have been shown to be needed for production of siderophores and antibiotics, our study presents the first case of one such gene proven to be required for production of a cell wall component. Furthermore, our results provide the first example of a mbtH-like gene with confirmed functional role in a member of the Mycobacterium genus. Altogether, our findings demonstrate a critical role of gplH in mycobacterial biology and advance our understanding of the genetic requirements for the biosynthesis of an important group of constituents of the mycobacterial outer membrane.
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Affiliation(s)
- Elizabeth Tatham
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
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24
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García Guerreiro MP. What makes transposable elements move in the Drosophila genome? Heredity (Edinb) 2012; 108:461-8. [PMID: 21971178 PMCID: PMC3330689 DOI: 10.1038/hdy.2011.89] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/22/2011] [Accepted: 08/25/2011] [Indexed: 11/08/2022] Open
Abstract
Transposable elements (TEs), by their capacity of moving and inducing mutations in the genome, are considered important drivers of species evolution. The successful invasions of TEs in genomes, despite their mutational properties, are an apparent paradox. TEs' transposition is usually strongly regulated to low value, but in some cases these elements can also show high transposition rates, which has been associated sometimes to changes in environmental conditions. It is evident that factors susceptible to induce transpositions in natural populations contribute to TE perpetuation. Different factors were proposed as causative agents of TE mobilization in a wide range of organisms: biotic and abiotic stresses, inter- and intraspecific crosses and populational factors. However, there is no clear evidence of the factors capable of inducing TE mobilization in Drosophila, and data on laboratory stocks show contradictory results. The aim of this review is to have an update critical revision about mechanisms promoting transposition of TEs in Drosophila, and to provide to the readers a global vision of the dynamics of these genomic elements in the Drosophila genome.
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Affiliation(s)
- M P García Guerreiro
- Grup de Biologia Evolutiva, Departament de Genètica i Microbiologia, Facultat de Biociències, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, Spain.
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25
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2007-2008. MASS SPECTROMETRY REVIEWS 2012; 31:183-311. [PMID: 21850673 DOI: 10.1002/mas.20333] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Revised: 01/04/2011] [Accepted: 01/04/2011] [Indexed: 05/31/2023]
Abstract
This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate-protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest.
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Affiliation(s)
- David J Harvey
- Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
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26
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Fujiwara N, Naka T, Ogawa M, Yamamoto R, Ogura H, Taniguchi H. Characteristics of Mycobacterium smegmatis J15cs strain lipids. Tuberculosis (Edinb) 2011; 92:187-92. [PMID: 22056691 DOI: 10.1016/j.tube.2011.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 09/26/2011] [Accepted: 10/10/2011] [Indexed: 11/16/2022]
Abstract
Mycobacterium smegmatis is a rapidly growing, non-pathogenic mycobacterium, and M. smegmatis strain mc(2)155 in particular has been used as a tool for molecular analysis of mycobacteria because of its high rate of transformation. We examined another strain, M. smegmatis J15cs, which has the advantage of surviving for six days in murine macrophages. The J15cs strain produces a rough dry colony, and we hypothesized that the long survival of the J15cs strain was correlated with its cell wall components. Therefore, the lipid compositions of these two strains were compared. The subclasses and carbon species of the mycolic acids were very similar, and the major glycolipids and phospholipids were expressed in both strains. However, apolar glycopeptidolipids were deleted only in the J15cs strain. The presence of apolar glycopeptidolipids gives the cell wall a different structure. Moreover, the apolar glycopeptidolipids were recognized by macrophages via toll-like receptor 2, but not 4. We concluded that the absence of apolar glycopeptidolipids is a definitive feature of the J15cs strain, and affects its morphology and survival in host cells.
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Affiliation(s)
- Nagatoshi Fujiwara
- Department of Bacteriology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, Osaka 545-8585, Japan.
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Structural basis for recognition of AT-rich DNA by unrelated xenogeneic silencing proteins. Proc Natl Acad Sci U S A 2011; 108:10690-5. [PMID: 21673140 DOI: 10.1073/pnas.1102544108] [Citation(s) in RCA: 167] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
H-NS and Lsr2 are nucleoid-associated proteins from Gram-negative bacteria and Mycobacteria, respectively, that play an important role in the silencing of horizontally acquired foreign DNA that is more AT-rich than the resident genome. Despite the fact that Lsr2 and H-NS proteins are dissimilar in sequence and structure, they serve apparently similar functions and can functionally complement one another. The mechanism by which these xenogeneic silencers selectively target AT-rich DNA has been enigmatic. We performed high-resolution protein binding microarray analysis to simultaneously assess the binding preference of H-NS and Lsr2 for all possible 8-base sequences. Concurrently, we performed a detailed structure-function relationship analysis of their C-terminal DNA binding domains by NMR. Unexpectedly, we found that H-NS and Lsr2 use a common DNA binding mechanism where a short loop containing a "Q/RGR" motif selectively interacts with the DNA minor groove, where the highest affinity is for AT-rich sequences that lack A-tracts. Mutations of the Q/RGR motif abolished DNA binding activity. Netropsin, a DNA minor groove-binding molecule effectively outcompeted H-NS and Lsr2 for binding to AT-rich sequences. These results provide a unified molecular mechanism to explain findings related to xenogeneic silencing proteins, including their lack of apparent sequence specificity but preference for AT-rich sequences. Our findings also suggest that structural information contained within the DNA minor groove is deciphered by xenogeneic silencing proteins to distinguish genetic material that is self from nonself.
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Deshayes C, Bach H, Euphrasie D, Attarian R, Coureuil M, Sougakoff W, Laval F, Av-Gay Y, Daffé M, Etienne G, Reyrat JM. MmpS4 promotes glycopeptidolipids biosynthesis and export in Mycobacterium smegmatis. Mol Microbiol 2010; 78:989-1003. [DOI: 10.1111/j.1365-2958.2010.07385.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Mycobacterial biofilms facilitate horizontal DNA transfer between strains of Mycobacterium smegmatis. J Bacteriol 2010; 192:5134-42. [PMID: 20675473 DOI: 10.1128/jb.00650-10] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Conjugal transfer of chromosomal DNA between strains of Mycobacterium smegmatis occurs by a novel mechanism. In a transposon mutagenesis screen, three transfer-defective insertions were mapped to the lsr2 gene of the donor strain mc(2)155. Because lsr2 encodes a nonspecific DNA-binding protein, mutations of lsr2 give rise to a variety of phenotypes, including an inability to form biofilms. In this study, we show that efficient DNA transfer between strains of M. smegmatis occurs in a mixed biofilm and that the process requires expression of lsr2 in the donor but not in the recipient strain. Testing cells from different strata of standing cultures showed that transfer occurred predominantly at the biofilm air-liquid interface, as other strata containing higher cell densities produced very few transconjugants. These data suggest that the biofilm plays a role beyond mere facilitation of cell-cell contact. Surprisingly, we found that under standard assay conditions the recipient strain does not form a biofilm. Taking these results together, we conclude that for transfer to occur, the recipient strain is actively recruited into the biofilm. In support of this idea, we show that donor and recipient cells are present in almost equal numbers in biofilms that produce transconjugants. Our demonstration of genetic exchange between mycobacteria in a mixed biofilm suggests that conjugation occurs in the environment. Since biofilms are considered to be the predominant natural microhabitat for bacteria, our finding emphasizes the importance of studying biological and physical processes that occur between cells in mixed biofilms.
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Correlation of the capsular phenotype in Propionibacterium freudenreichii with the level of expression of gtf, a unique polysaccharide synthase-encoding gene. Appl Environ Microbiol 2010; 76:2740-6. [PMID: 20228100 DOI: 10.1128/aem.02591-09] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many food-grade bacteria produce exopolysaccharides (EPS) that affect the texture of fermented food products and that may be involved in probiotic properties. Propionibacterium freudenreichii is a Gram-positive food-grade bacterium with reported probiotic capabilities that is widely used as starter in Swiss-type cheese. In this study, 68 strains of P. freudenreichii were screened for the beta-glucan capsular phenotype by immunoagglutination with a specific antibody and for the presence of the gtf gene coding for polysaccharide synthase. All strains were positive for PCR amplification with gtf gene-specific primers, but the presence of beta-glucan capsular EPS was detected for only 35% of the strains studied. Disruption of gtf in P. freudenreichii revealed that gtf is a unique gene involved in beta-glucan capsular EPS production in P. freudenreichii. The gtf gene was transferred into and expressed in Lactococcus lactis, in which it conferred an agglutination-positive phenotype. Expression of the gtf gene was measured by performing quantitative reverse transcription-PCR assays with RNA from four capsular and three noncapsular strains. A positive correlation was found between the beta-glucan capsular phenotype and gtf gene expression. Sequencing of the region upstream of the gtf open reading frame revealed the presence of an insertion element (IS element) in this upstream region in the four strains with the beta-glucan capsular phenotype. The role of the IS element in the expression of neighboring genes and its impact on interstrain variability of the P. freudenreichii capsule phenotype remain to be elucidated.
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Lsr2 is a nucleoid-associated protein that targets AT-rich sequences and virulence genes in Mycobacterium tuberculosis. Proc Natl Acad Sci U S A 2010; 107:5154-9. [PMID: 20133735 DOI: 10.1073/pnas.0913551107] [Citation(s) in RCA: 159] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Bacterial nucleoid-associated proteins play important roles in chromosome organization and global gene regulation. We find that Lsr2 of Mycobacterium tuberculosis is a unique nucleoid-associated protein that binds AT-rich regions of the genome, including genomic islands acquired by horizontal gene transfer and regions encoding major virulence factors, such as the ESX secretion systems, the lipid virulence factors PDIM and PGL, and the PE/PPE families of antigenic proteins. Comparison of genome-wide binding data with expression data indicates that Lsr2 binding results in transcriptional repression. Domain-swapping experiments demonstrate that Lsr2 has an N-terminal dimerization domain and a C-terminal DNA-binding domain. Nuclear magnetic resonance analysis of the DNA-binding domain of Lsr2 and its interaction with DNA reveals a unique structure and a unique mechanism that enables Lsr2 to discriminately target AT-rich sequences through interactions with the minor groove of DNA. Taken together, we provide evidence that mycobacteria have employed a structurally distinct molecule with an apparently different DNA recognition mechanism to achieve a function similar to the Enterobacteriaceae H-NS, likely coordinating global gene regulation and virulence in this group of medically important bacteria.
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Mycobacterium abscessus: a new player in the mycobacterial field. Trends Microbiol 2010; 18:117-23. [PMID: 20060723 DOI: 10.1016/j.tim.2009.12.007] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 11/25/2009] [Accepted: 12/09/2009] [Indexed: 11/24/2022]
Abstract
Mycobacterium abscessus, a relative of Koch's bacillus (the bacterium that causes tuberculosis), has recently emerged as the cause of an increasing number of both community- and hospital-acquired infections in humans; it also constitutes a serious threat for cystic fibrosis patients. This situation is worsened by its exceptionally high natural and acquired antibiotic resistance that complicates treatment. Although a rapid grower, it shares some traits with Koch's bacillus, including the ability to induce a persistent lung disease associated with caseous lesions, a landmark of Mycobacterium tuberculosis infection. Its genome sequence and microarrays are now available, and efficient genetic tools have recently been developed. Here we consider the various advantages of using this species as an experimental model to study tuberculosis and other related mycobacterial diseases.
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Abstract
This unit gives background information on Mycobacterium smegmatis, a mycobacterial model system, and covers all the laboratory maintenance for this species including growth in liquid and on solid medium. It also contains recommendations concerning long-term strain storage. Although M. smegmatis is a Biosafety Level 1 organism, some rare infections in humans have been reported, and, thus all of the required safety measures are discussed here.
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Identification of the polyketide synthase involved in the biosynthesis of the surface-exposed lipooligosaccharides in mycobacteria. J Bacteriol 2009; 191:2613-21. [PMID: 19181796 DOI: 10.1128/jb.01235-08] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipooligosaccharides (LOS) are highly antigenic glycolipids produced by a number of Mycobacterium species, which include "M. canettii," a member of the M. tuberculosis complex, and the opportunistic pathogens M. marinum and M. kansasii. The various LOS share a core composed of trehalose esterified by at least 1 mole of polymethyl-branched fatty acid (PMB-FA) and differ from one another by their oligosaccharide extensions. In this study, we identified a cluster of genes, MSMEG_4727 through MSMEG_4741, likely involved in the synthesis of LOS in M. smegmatis. Disruption of MSMEG_4727 (the ortholog of pks5 of M. tuberculosis), which encodes a putative polyketide synthase, resulted in the concomitant abrogation of the production of both PMB-FA and LOS in the mutant strain. Complementation of the mutant with the wild-type gene fully restored the phenotype. We also showed that, in contrast to the case for "M. canettii" and M. marinum, LOS are located in deeper compartments of the cell envelope of M. smegmatis. The availability of two mycobacterial strains differing only in LOS production should help in defining the biological role(s) of this important glycolipid.
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SigF controls carotenoid pigment production and affects transformation efficiency and hydrogen peroxide sensitivity in Mycobacterium smegmatis. J Bacteriol 2008; 190:7859-63. [PMID: 18805974 DOI: 10.1128/jb.00714-08] [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
Carotenoids are complex lipids that are known for acting against photodynamic injury and free radicals. We demonstrate here that sigma(F) is required for carotenoid pigment production in Mycobacterium smegmatis. We further show that a sigF mutant exhibits a transformation efficiency 10(4)-fold higher than that of the parental strain, suggesting that sigma(F) regulates the production of components affecting cell wall permeability. In addition, a sigF mutant showed an increased sensitivity to hydrogen peroxide. An in silico search of the M. smegmatis genome identified a number of SigF consensus sites, including sites upstream of the carotenoid synthesis locus, which explains its SigF regulation.
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Abstract
Lsr2 is a small, basic protein present in Mycobacterium and related actinomycetes. Our previous in vitro biochemical studies showed that Lsr2 is a DNA-bridging protein, a property shared by H-NS-like proteins in gram-negative bacteria. Here we present in vivo evidence based on genetic complementation experiments that Lsr2 is a functional analog of H-NS, the first such protein identified in gram-positive bacteria. We show that lsr2 can complement the phenotypes related to hns mutations in Escherichia coli, including beta-glucoside utilization, mucoidy, motility, and hemolytic activity. We also show that Lsr2 binds specifically to H-NS-regulated genes and the repression of hlyE by Lsr2 can be partially eliminated by overexpression of slyA, suggesting that the molecular mechanisms of Lsr2 repression and depression are similar to those of H-NS. The functional equivalence of these two proteins is further supported by the ability of hns to complement the lsr2 phenotype in Mycobacterium smegmatis. Taken together, our results demonstrate unequivocally that Lsr2 is an H-NS-like protein.
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