-
Vitamin B uptake across the mycobacterial outer membrane is influenced by membrane permeability in .Microbiology Spectrum Jun 2024Vitamin B (B) serves as a critical cofactor within mycobacterial metabolism. While some pathogenic strains can synthesize B , others rely on host-acquired B. In this...
Vitamin B (B) serves as a critical cofactor within mycobacterial metabolism. While some pathogenic strains can synthesize B , others rely on host-acquired B. In this investigation, we studied the transport of vitamin B in using B-auxotrophic and B-sensitive strains by deleting or , respectively. These two enzymes rely on B in different ways to function as methionine synthases. We used these strains to select mutants affecting B scavenging and confirmed their phenotypes during growth experiments . Our analysis of B uptake mechanisms revealed that membrane lipids and cell wall integrity play an essential role in cell envelope transport. Furthermore, we identified a potential transcription regulator that responds to B. Our study demonstrates that can take up exogenous B and that altering mycobacterial membrane integrity affects B uptake. Finally, during zebrafish infection using B-auxotrophic and B-sensitive strains, we found that B is available for virulent mycobacteria .IMPORTANCEOur study investigates how mycobacteria acquire essential vitamin B. These microbes, including those causing tuberculosis, face challenges in nutrient uptake due to their strong outer layer. We focused on , similar to TB bacteria, to uncover its vitamin B absorption. We used modified strains unable to produce their own B and discovered that can indeed absorb it from the environment, even during infections. Changes in the outer layer composition affect this process, and genes related to membrane integrity play key roles. These findings illuminate the interaction between mycobacteria and their environment, offering insights into combatting diseases like tuberculosis through innovative strategies. Our concise research underscores the pivotal role of vitamin B in microbial survival and its potential applications in disease control.
Topics: Mycobacterium marinum; Vitamin B 12; Animals; Zebrafish; Bacterial Outer Membrane; Bacterial Proteins; Cell Membrane Permeability; Biological Transport; Cell Membrane; Mycobacterium Infections, Nontuberculous
PubMed: 38722177
DOI: 10.1128/spectrum.03168-23 -
The Journal of Antibiotics Jul 2024Three new liposidomycin congeners (1, 2, and 4), together with 14 known liposidomycins (3 and 5-17), were isolated from the culture broth of Streptomyces sp. TMPU-20A065...
Three new liposidomycin congeners (1, 2, and 4), together with 14 known liposidomycins (3 and 5-17), were isolated from the culture broth of Streptomyces sp. TMPU-20A065 as anti-Mycobacterium avium complex agents. The structures of liposidomycins were elucidated by spectroscopic analyses, including NMR and MS. Compounds 1, 2, and 4 belong to type-I liposidomycin-containing sulfate groups and methylglutaric acid, each with a different acyl side chain in the structure. Compounds 1-17 exhibited in vitro anti-M. avium and M. intracellulare activities with MIC values ranging between 2.0 and 64 μg ml. Furthermore, 1-17 exerted potent therapeutic effects in an in vivo-mimic silkworm infection model with ED values ranging between 0.12 and 3.7 μg larva g.
Topics: Animals; Streptomyces; Bombyx; Microbial Sensitivity Tests; Anti-Bacterial Agents; Mycobacterium avium Complex; Magnetic Resonance Spectroscopy; Disease Models, Animal; Molecular Structure
PubMed: 38720140
DOI: 10.1038/s41429-024-00724-4 -
Frontiers in Immunology 2024complex (MAC) is a non-tuberculous mycobacterium widely distributed in the environment. Even though MAC infection is increasing in older women and immunocompromised...
complex (MAC) is a non-tuberculous mycobacterium widely distributed in the environment. Even though MAC infection is increasing in older women and immunocompromised patients, to our knowledge there has been no comprehensive analysis of the MAC-infected host-cell transcriptome-and particularly of long non-coding RNAs (lncRNAs). By using cultured primary mouse bone-marrow-derived macrophages (BMDMs) and Cap analysis of gene expression, we analyzed the transcriptional and kinetic landscape of macrophage genes, with a focus on lncRNAs, during MAC infection. MAC infection of macrophages induced the expression of immune/inflammatory response genes and other genes similar to those involved in M1 macrophage activation, consistent with previous reports, although (M1 activation) and (M2 activation) had distinct expression profiles. We identified 31 upregulated and 30 downregulated lncRNA promoters corresponding respectively to 18 and 26 lncRNAs. Upregulated lncRNAs were clustered into two groups-early and late upregulated-predicted to be associated with immune activation and the immune response to infection, respectively. Furthermore, an Ingenuity Pathway Analysis revealed canonical pathways and upstream transcription regulators associated with differentially expressed lncRNAs. Several differentially expressed lncRNAs reported elsewhere underwent expressional changes upon M1 or M2 preactivation and subsequent MAC infection. Finally, we showed that expressional change of lncRNAs in MAC-infected BMDMs was mediated by toll-like receptor 2, although there may be other mechanisms that sense MAC infection. We identified differentially expressed lncRNAs in MAC-infected BMDMs, revealing diverse features that imply the distinct roles of these lncRNAs in MAC infection and macrophage polarization.
Topics: RNA, Long Noncoding; Animals; Macrophages; Mycobacterium avium Complex; Mice; Gene Expression Profiling; Mycobacterium avium-intracellulare Infection; Transcriptome; Macrophage Activation; Mice, Inbred C57BL; Cells, Cultured; Gene Expression Regulation
PubMed: 38711507
DOI: 10.3389/fimmu.2024.1374437 -
Scientific Reports May 2024Mammals are generally resistant to Mycobacterium avium complex (MAC) infections. We report here on a primary immunodeficiency disorder causing increased susceptibility...
Mammals are generally resistant to Mycobacterium avium complex (MAC) infections. We report here on a primary immunodeficiency disorder causing increased susceptibility to MAC infections in a canine breed. Adult Miniature Schnauzers developing progressive systemic MAC infections were related to a common founder, and pedigree analysis was consistent with an autosomal recessive trait. A genome-wide association study and homozygosity mapping using 8 infected, 9 non-infected relatives, and 160 control Miniature Schnauzers detected an associated region on chromosome 9. Whole genome sequencing of 2 MAC-infected dogs identified a codon deletion in the CARD9 gene (c.493_495del; p.Lys165del). Genotyping of Miniature Schnauzers revealed the presence of this mutant CARD9 allele worldwide, and all tested MAC-infected dogs were homozygous mutants. Peripheral blood mononuclear cells from a dog homozygous for the CARD9 variant exhibited a dysfunctional CARD9 protein with impaired TNF-α production upon stimulation with the fungal polysaccharide β-glucan that activates the CARD9-coupled C-type lectin receptor, Dectin-1. While CARD9-deficient knockout mice are susceptible to experimental challenges by fungi and mycobacteria, Miniature Schnauzer dogs with systemic MAC susceptibility represent the first spontaneous animal model of CARD9 deficiency, which will help to further elucidate host defense mechanisms against mycobacteria and fungi and assess potential therapies for animals and humans.
Topics: Animals; CARD Signaling Adaptor Proteins; Dogs; Genetic Predisposition to Disease; Mycobacterium avium-intracellulare Infection; Mycobacterium avium Complex; Genome-Wide Association Study; Dog Diseases; Sequence Deletion; Pedigree; Female; Male; Whole Genome Sequencing; Homozygote; Lectins, C-Type
PubMed: 38710903
DOI: 10.1038/s41598-024-61054-x -
PLoS Neglected Tropical Diseases May 2024Critical scientific questions remain regarding infection with Mycobacterium ulcerans, the organism responsible for the neglected tropical disease, Buruli ulcer (BU). A...
Critical scientific questions remain regarding infection with Mycobacterium ulcerans, the organism responsible for the neglected tropical disease, Buruli ulcer (BU). A controlled human infection model has the potential to accelerate our knowledge of the immunological correlates of disease, to test prophylactic interventions and novel therapeutics. Here we present microbiological evidence supporting M. ulcerans JKD8049 as a suitable human challenge strain. This non-genetically modified Australian isolate is susceptible to clinically relevant antibiotics, can be cultured in animal-free and surfactant-free media, can be enumerated for precise dosing, and has stable viability following cryopreservation. Infectious challenge of humans with JKD8049 is anticipated to imitate natural infection, as M. ulcerans JKD8049 is genetically stable following in vitro passage and produces the key virulence factor, mycolactone. Also reported are considerations for the manufacture, storage, and administration of M. ulcerans JKD8049 for controlled human infection.
Topics: Mycobacterium ulcerans; Buruli Ulcer; Humans; Anti-Bacterial Agents; Australia
PubMed: 38701090
DOI: 10.1371/journal.pntd.0011979 -
Microbiology Spectrum Jun 2024Four species of non-tuberculous mycobacteria (NTM) rated as biosafety level 1 or 2 (BSL-1/BSL-2) organisms and showing higher genomic similarity with () than previous...
Four species of non-tuberculous mycobacteria (NTM) rated as biosafety level 1 or 2 (BSL-1/BSL-2) organisms and showing higher genomic similarity with () than previous comparator species and were subjected to genomic and phenotypic characterization. These species named , , and might represent "missing links" between low-virulent mycobacterial opportunists and the highly virulent obligate pathogen . We confirmed that is the closest NTM species to currently known and found that it has an optimal growth temperature of 32°C-35°C and not 37°C. showed resistance to rifampicin, isoniazid, and ethambutol, whereas and showed resistance to isoniazid and ethambutol. was sensitive to all three first-line TB drugs, and all four species were sensitive to bedaquiline, a third-generation anti-TB drug. Our results suggest these four NTM may be useful models for the identification and study of new anti-TB molecules, facilitated by their culture under non-BSL-3 conditions as compared to was the most virulent of the four species in cellular and mouse infection models. also multiplied in THP-1 cells at 35°C but was growth impaired at 37°C. Genomic comparisons showed that the locus, essential for the secretion of ESX-1 proteins in , was present only in , which was able to secrete ESAT-6 and CFP-10, whereas secretion of these antigens varied in the other species, making the four species interesting examples for studying ESX-1 secretion mechanisms.IMPORTANCEIn this work, we investigated recently identified opportunistic mycobacterial pathogens that are genomically more closely related to () than previously used comparator species and . We confirmed that is the currently closest known species to the tubercle bacilli, represented by and strains. Surprisingly, the reference strain of (DSM 45176), which was purchased as a biosafety level 1 (BSL-1)-rated organism, was the most virulent of the four species in the tested cellular and mouse infection models, suggesting that a BSL-2 rating might be more appropriate for this strain than the current BSL-1 rating. Our work establishes the four NTM species as interesting study models to obtain new insights into the evolutionary mechanisms and phenotypic particularities of mycobacterial pathogens that likely have also impacted the evolution of the key pathogen .
Topics: Mycobacterium tuberculosis; Antitubercular Agents; Nontuberculous Mycobacteria; Humans; Genome, Bacterial; Genomics; Phenotype; Microbial Sensitivity Tests; Mycobacterium Infections, Nontuberculous; Phylogeny; Animals; Tuberculosis; Drug Resistance, Bacterial; Mice
PubMed: 38700329
DOI: 10.1128/spectrum.04126-23 -
Cellular and Molecular Life Sciences :... May 2024Nitrogen metabolism of M. tuberculosis is critical for its survival in infected host cells. M. tuberculosis has evolved sophisticated strategies to switch between de...
Nitrogen metabolism of M. tuberculosis is critical for its survival in infected host cells. M. tuberculosis has evolved sophisticated strategies to switch between de novo synthesis and uptake of various amino acids from host cells for metabolic demands. Pyridoxal phosphate-dependent histidinol phosphate aminotransferase-HspAT enzyme is critically required for histidine biosynthesis. HspAT is involved in metabolic synthesis of histidine, phenylalanine, tyrosine, tryptophan, and novobiocin. We showed that M. tuberculosis Rv2231c is a conserved enzyme with HspAT activity. Rv2231c is a monomeric globular protein that contains α-helices and β-sheets. It is a secretory and cell wall-localized protein that regulates critical pathogenic attributes. Rv2231c enhances the survival and virulence of recombinant M. smegmatis in infected RAW264.7 macrophage cells. Rv2231c is recognized by the TLR4 innate immune receptor and modulates the host immune response by suppressing the secretion of the antibacterial pro-inflammatory cytokines TNF, IL-12, and IL-6. It also inhibits the expression of co-stimulatory molecules CD80 and CD86 along with antigen presenting molecule MHC-I on macrophage and suppresses reactive nitrogen species formation, thereby promoting M2 macrophage polarization. Recombinant M. smegmatis expressing Rv2231c inhibited apoptosis in macrophages, promoting efficient bacterial survival and proliferation, thereby increasing virulence. Our results indicate that Rv2231c is a moonlighting protein that regulates multiple functions of M. tuberculosis pathophysiology to increase its virulence. These mechanistic insights can be used to better understand the pathogenesis of M. tuberculosis and to design strategies for tuberculosis mitigation.
Topics: Mice; Mycobacterium tuberculosis; Animals; RAW 264.7 Cells; Virulence; Macrophages; Transaminases; Bacterial Proteins; Mycobacterium smegmatis; Cytokines; Toll-Like Receptor 4; Humans; Immunity, Innate; Host-Pathogen Interactions; Tuberculosis
PubMed: 38698289
DOI: 10.1007/s00018-024-05200-8 -
The European Respiratory Journal May 2024https://bit.ly/3PUGvbV
https://bit.ly/3PUGvbV
Topics: Humans; Mycobacterium avium-intracellulare Infection; Rifampin; Mycobacterium avium Complex; Anti-Bacterial Agents; Lung Diseases; Treatment Outcome
PubMed: 38697635
DOI: 10.1183/13993003.02210-2023 -
Journal of Clinical Tuberculosis and... May 2024Nontuberculous mycobacteria are a rare but still emerging cause of difficult-to-treat prosthetic joint infection. To our knowledge only 17 cases of prosthetic joint... (Review)
Review
Nontuberculous mycobacteria are a rare but still emerging cause of difficult-to-treat prosthetic joint infection. To our knowledge only 17 cases of prosthetic joint infection are reported in literature, of which only 1 is by . No guidelines are available for this clinical scenario. We describe a 68-years-old female patient with an early-onset prosthetic joint infection, successfully treated with a tailored medical-surgical strategy, and present an overview of cases currently available in the literature to assist physicians in the management of these uncommon infections.
PubMed: 38694253
DOI: 10.1016/j.jctube.2024.100440 -
Antimicrobial Agents and Chemotherapy May 2024The dual β-lactam approach has been successfully applied to overcome target redundancy in nontuberculous mycobacteria. Surprisingly, this approach has not been...
The dual β-lactam approach has been successfully applied to overcome target redundancy in nontuberculous mycobacteria. Surprisingly, this approach has not been leveraged for despite the high conservation of peptidoglycan synthesis. Through a comprehensive screen of oral β-lactam pairs, we have discovered that cefuroxime strongly potentiates the bactericidal activity of tebipenem and sulopenem-advanced clinical candidates-and amoxicillin, at concentrations achieved clinically. β-lactam pairs thus have the potential to reduce TB treatment duration.
PubMed: 38690896
DOI: 10.1128/aac.00034-24