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MSphere May 2024The mycobacterial cell envelope is a major virulence determinant in pathogenic mycobacteria. Specific outer lipids play roles in pathogenesis, modulating the immune...
The mycobacterial cell envelope is a major virulence determinant in pathogenic mycobacteria. Specific outer lipids play roles in pathogenesis, modulating the immune system and promoting the secretion of virulence factors. ESX-1 (ESAT-6 system-1) is a conserved protein secretion system required for mycobacterial pathogenesis. Previous studies revealed that mycobacterial strains lacking the outer lipid PDIM have impaired ESX-1 function during laboratory growth and infection. The mechanisms underlying changes in ESX-1 function are unknown. We used a proteo-genetic approach to measure phthiocerol dimycocerosate (PDIM)- and phenolic glycolipid (PGL)-dependent protein secretion in a non-tubercular mycobacterial pathogen that causes tuberculosis-like disease in ectothermic animals. Importantly, is a well-established model for mycobacterial pathogenesis. Our findings showed that strains without PDIM and PGL showed specific, significant reductions in protein secretion compared to the WT and complemented strains. We recently established a hierarchy for the secretion of ESX-1 substrates in four (I-IV) groups. Loss of PDIM differentially impacted secretion of Group III and IV ESX-1 substrates, which are likely the effectors of pathogenesis. Our data suggest that the altered secretion of specific ESX-1 substrates is responsible for the observed ESX-1-related effects in PDIM-deficient strains.IMPORTANCE the cause of human tuberculosis, killed an estimated 1.3 million people in 2022. Non-tubercular mycobacterial species cause acute and chronic human infections. Understanding how these bacteria cause disease is critical. Lipids in the cell envelope are essential for mycobacteria to interact with the host and promote disease. Strains lacking outer lipids are attenuated for infection, but the reasons are unclear. Our research aims to identify a mechanism for attenuation of mycobacterial strains without the PDIM and PGL outer lipids in . These findings will enhance our understanding of the importance of lipids in pathogenesis and how these lipids contribute to other established virulence mechanisms.
Topics: Mycobacterium marinum; Bacterial Proteins; Virulence Factors; Glycolipids; Virulence; Lipids; Antigens, Bacterial
PubMed: 38661343
DOI: 10.1128/msphere.00005-24 -
Indian Journal of Gastroenterology :... Apr 2024
PubMed: 38652376
DOI: 10.1007/s12664-024-01572-8 -
Open Forum Infectious Diseases Apr 2024The objective of our study is to describe the clinical presentation, management, and outcome of a large cohort with nontuberculous mycobacteria (NTM) hand infection.
BACKGROUND
The objective of our study is to describe the clinical presentation, management, and outcome of a large cohort with nontuberculous mycobacteria (NTM) hand infection.
METHODS
We reviewed the medical records of all adults (≥18 years) managed at the Mayo Clinic (Rochester, MN) for NTM hand infection between 1998 and 2018.
RESULTS
Our cohort included 81 patients. The median age was 61.3 (interquartile range 51.7, 69.6) years; 39.5% were immunocompromised, and 67.9% reported a triggering exposure preceding infection. Infection was deep in 64.2% and disseminated in 3.7%. Up to 16.0% received intralesional steroids because of misdiagnosis with an inflammatory process. Immunocompromised patients had deeper infection, and fewer reports of a triggering exposure. , complex, and complex were the most common species. The median antibiotic duration was 6.1 (interquartile range 4.6, 9.9) months. Deep infection and infection with species other than were associated with using a greater number of antibiotics for combination therapy and an extended duration of treatment. Immunosuppression was also associated with longer courses of antibiotic therapy. Surgery was performed in 86.5% and 32.4% required multiple procedures. Ten patients, mostly with superficial infections, were treated with antibiotics alone. The 5-year cumulative rate of treatment failure was 30.3% (95% confidence interval, 20.9-44.0). Immunosuppression and intralesional steroid use were risk factors for failure.
CONCLUSIONS
Treatment of NTM hand infection usually requires surgery and antibiotics, but antibiotics alone may occasionally be attempted in select cases. Immunosuppression and intralesional steroids are risk factors for treatment failure.
PubMed: 38651140
DOI: 10.1093/ofid/ofae152 -
MSphere Apr 2024(), the pathogenic bacterium that causes tuberculosis, has evolved sophisticated defense mechanisms to counteract the cytotoxicity of reactive oxygen species (ROS)...
UNLABELLED
(), the pathogenic bacterium that causes tuberculosis, has evolved sophisticated defense mechanisms to counteract the cytotoxicity of reactive oxygen species (ROS) generated within host macrophages during infection. The gene in and () plays a crucial role in defense mechanisms against ROS generated during infection. We demonstrate that encodes an epoxide hydrolase and contributes to ROS detoxification. Deletion of in resulted in a mutant with increased sensitivity to oxidative stress, increased accumulation of aldehyde species, and decreased production of mycothiol and ergothioneine. This heightened vulnerability is attributed to the increased expression of , a universal stress sensor. The absence of also resulted in reduced intracellular levels of NAD, NADH, and ATP. Bacterial growth was impaired, even in the absence of external stressors, and the impairment was carbon source dependent. Initial MelH substrate specificity studies demonstrate a preference for epoxides with a single aromatic substituent. Taken together, these results highlight the role of in mycobacterial bioenergetic metabolism and provide new insights into the complex interplay between redox homeostasis and generation of reactive aldehyde species in mycobacteria.
IMPORTANCE
This study unveils the pivotal role played by the gene in and in in combatting the detrimental impact of oxidative conditions during infection. This investigation revealed notable alterations in the level of cytokinin-associated aldehyde, -hydroxybenzaldehyde, as well as the redox buffer ergothioneine, upon deletion of . Moreover, changes in crucial cofactors responsible for electron transfer highlighted 's crucial function in maintaining a delicate equilibrium of redox and bioenergetic processes. MelH prefers epoxide small substrates with a phenyl substituted substrate. These findings collectively emphasize the potential of as an attractive target for the development of novel antitubercular therapies that sensitize mycobacteria to host stress, offering new avenues for combating tuberculosis.
Topics: Mycobacterium tuberculosis; Homeostasis; Oxidation-Reduction; Energy Metabolism; Oxidative Stress; Bacterial Proteins; Reactive Oxygen Species; Antitubercular Agents; Ergothioneine; Inositol; Mycobacterium marinum; Gene Deletion; Cysteine; Glycopeptides
PubMed: 38564709
DOI: 10.1128/msphere.00061-24 -
Marine Drugs Mar 2024With the emergence of drug-resistant strains, the treatment of tuberculosis (TB) is becoming more difficult and there is an urgent need to find new anti-TB drugs. , as a...
With the emergence of drug-resistant strains, the treatment of tuberculosis (TB) is becoming more difficult and there is an urgent need to find new anti-TB drugs. , as a model organism of , can be used for the rapid and efficient screening of bioactive compounds. The 14-membered resorcylic acid lactones (RALs) have a wide range of bioactivities such as antibacterial, antifouling and antimalarial activity. In order to further study their bioactivities, we initially constructed a 14-membered RALs library, which contains 16 new derivatives. The anti- activity was evaluated in vitro. Derivatives , , and exhibited promising activity with MIC values of 80, 90, 80 and 80 μM, respectively. The preliminary structure-activity relationships showed that the presence of a chlorine atom at C-5 was a key factor to improve activity. Further studies showed that markedly inhibited the survival of and significantly reduced the dosage of positive drugs isoniazid and rifampicin when combined with them. These results suggest that is a bioactive compound capable of enhancing the potency of existing positive drugs, and its effective properties make it a very useful leads for future drug development in combating TB resistance.
Topics: Mycobacterium marinum; Antibodies; Antimalarials; Antitubercular Agents; Lactones
PubMed: 38535476
DOI: 10.3390/md22030135 -
Microbiology Resource Announcements Apr 2024N-terminal acetylation in is correlated with pathogenic activity. We used genomics and bottom-up proteomics to identify protein Emp1 as the sole acetyltransferase...
N-terminal acetylation in is correlated with pathogenic activity. We used genomics and bottom-up proteomics to identify protein Emp1 as the sole acetyltransferase responsible for acetylation of EsxA, a known virulence factor. Using custom data analysis, we screened the proteome to identify 22 additional putative substrates of Emp1.
PubMed: 38477461
DOI: 10.1128/mra.01263-23 -
MBio Apr 2024Bacterial pathogens use protein secretion systems to transport virulence factors and regulate gene expression. Among pathogenic mycobacteria, including and , the ESAT-6...
Bacterial pathogens use protein secretion systems to transport virulence factors and regulate gene expression. Among pathogenic mycobacteria, including and , the ESAT-6 system 1 (ESX-1) secretion is crucial for host interaction. Secretion of protein substrates by the ESX-1 secretion system disrupts phagosomes, allowing mycobacteria cytoplasmic access during macrophage infections. Deletion or mutation of the ESX-1 system attenuates mycobacterial pathogens. Pathogenic mycobacteria respond to the presence or absence of the ESX-1 system in the cytoplasmic membrane by altering transcription. Under laboratory conditions, the EspM repressor and WhiB6 activator control transcription of specific ESX-1-responsive genes, including the ESX-1 substrate genes. However, deleting the or gene does not phenocopy the deletion of the ESX-1 substrate genes during macrophage infection by . In this study, we identified EspN, a critical transcription factor whose activity is masked by the EspM repressor under laboratory conditions. In the absence of EspM, EspN activates transcription of and ESX-1 genes during both laboratory growth and macrophage infection. EspN is also independently required for growth within and cytolysis of macrophages, similar to the ESX-1 genes, and for disease burden in a zebrafish larval model of infection. These findings suggest that EspN and EspM coordinate to counterbalance the regulation of the ESX-1 system and support mycobacterial pathogenesis.IMPORTANCEPathogenic mycobacteria, which are responsible for tuberculosis and other long-term diseases, use the ESX-1 system to transport proteins that control the host response to infection and promote bacterial survival. In this study, we identify an undescribed transcription factor that controls the expression of ESX-1 genes and is required for both macrophage and animal infection. However, this transcription factor is not the primary regulator of ESX-1 genes under standard laboratory conditions. These findings identify a critical transcription factor that likely controls expression of a major virulence pathway during infection, but whose effect is not detectable with standard laboratory strains and growth conditions.
Topics: Animals; Transcription Factors; Bacterial Proteins; Type VII Secretion Systems; Zebrafish; Tuberculosis; Mycobacterium tuberculosis; Mycobacterium marinum
PubMed: 38445877
DOI: 10.1128/mbio.03357-23 -
ACS Chemical Biology Mar 2024Surface lipids on pathogenic mycobacteria modulate infection outcomes by regulating host immune responses. Phenolic glycolipid (PGL) is a host-modulating surface lipid...
Surface lipids on pathogenic mycobacteria modulate infection outcomes by regulating host immune responses. Phenolic glycolipid (PGL) is a host-modulating surface lipid that varies among clinical strains. PGL is also found in , where it promotes infection of zebrafish through effects on the innate immune system. Given the important role this lipid plays in the host-pathogen relationship, tools for profiling its abundance, spatial distribution, and dynamics are needed. Here, we report a strategy for imaging PGL in live mycobacteria using bioorthogonal metabolic labeling. We functionalized the PGL precursor -hydroxybenzoic acid (HB) with an azide group (3-azido HB). When fed to mycobacteria, 3-azido HB was incorporated into the cell surface, which could then be visualized the bioorthogonal conjugation of a fluorescent probe. We confirmed that 3-azido HB incorporates into PGL using mass spectrometry methods and demonstrated selectivity for PGL-producing and strains. Finally, we applied this metabolic labeling strategy to study the dynamics of PGL within the mycobacterial membrane. This new tool enables visualization of PGL that may facilitate studies of mycobacterial pathogenesis.
Topics: Animals; Glycolipids; Virulence Factors; Zebrafish; Mycobacterium tuberculosis; Mycobacterium marinum
PubMed: 38442242
DOI: 10.1021/acschembio.3c00724 -
Archives of Biochemistry and Biophysics Apr 2024The cytochrome P450 family of heme metalloenzymes (CYPs) catalyse important biological monooxygenation reactions. Mycobacterium marinum contains a gene encoding a...
The cytochrome P450 family of heme metalloenzymes (CYPs) catalyse important biological monooxygenation reactions. Mycobacterium marinum contains a gene encoding a CYP105Q4 enzyme of unknown function. Other members of the CYP105 CYP family have key roles in bacterial metabolism including the synthesis of secondary metabolites. We produced and purified the cytochrome P450 enzyme CYP105Q4 to enable its characterization. Several nitrogen-donor atom-containing ligands were found to bind to CYP105Q4 generating type II changes in the UV-vis absorbance spectrum. Based on the UV-vis absorbance spectra none of the potential substrate ligands we tested with CYP105Q4 were able to displace the sixth distal aqua ligand from the heme, though there was evidence for binding of oleic acid and amphotericin B. The crystal structure of CYP105Q4 in the substrate-free form was determined in an open conformation. A computational structural similarity search (Dali) was used to find the most closely related characterized relatives within the CYP105 family. The structure of CYP105Q4 enzyme was compared to the GfsF CYP enzyme from Streptomyces graminofaciens which is involved in the biosynthesis of a macrolide polyketide. This structural comparison to GfsF revealed conformational changes in the helices and loops near the entrance to the substrate access channel. A disordered B/C loop region, usually involved in substrate recognition, was also observed.
Topics: Mycobacterium marinum; Cytochrome P-450 Enzyme System; Protein Structure, Secondary; Macrolides; Heme; Crystallography, X-Ray
PubMed: 38430969
DOI: 10.1016/j.abb.2024.109950 -
IScience Mar 2024Pathogenic mycobacteria orchestrate the complex cell populations known as granuloma that is the hallmark of tuberculosis. Foam cells, a lipid-rich cell-type, are...
Pathogenic mycobacteria orchestrate the complex cell populations known as granuloma that is the hallmark of tuberculosis. Foam cells, a lipid-rich cell-type, are considered critical for granuloma formation; however, the causative factor in foam cell formation remains unclear. Atherosclerosis is a chronic inflammatory disease characterized by the abundant accumulation of lipid-laden-macrophage-derived foam cells during which cholesterol 25-hydroxylase (CH25H) is crucial in foam cell formation. Here, we show that . (), a relative of . , induces foam cell formation, leading to granuloma development following CH25H upregulation. Moreover, the -driven increase in CH25H expression is associated with the presence of phthiocerol dimycocerosate, a determinant for virulence and integrity. CH25H- mice showed decreased foam cell formation and attenuated pathology. Atorvastatin, a recommended first-line lipid-lowering drug, promoted the elimination of and concomitantly reduced CH25H production. These results define a previously unknown role for CH25H in controlling macrophage-derived foam cell formation and Tuberculosis pathology.
PubMed: 38420591
DOI: 10.1016/j.isci.2024.109204