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MBio Oct 2023N-terminal acetylation is a protein modification that broadly impacts basic cellular function and disease in higher organisms. Although bacterial proteins are...
N-terminal acetylation is a protein modification that broadly impacts basic cellular function and disease in higher organisms. Although bacterial proteins are N-terminally acetylated, little is understood how N-terminal acetylation impacts bacterial physiology and pathogenesis. Mycobacterial pathogens cause acute and chronic disease in humans and in animals. Approximately 15% of mycobacterial proteins are N-terminally acetylated, but the responsible enzymes are largely unknown. We identified a conserved mycobacterial protein required for the N-terminal acetylation of 23 mycobacterial proteins including the EsxA virulence factor. Loss of this enzyme from reduced macrophage killing and spread of to new host cells. Defining the acetyltransferases responsible for the N-terminal protein acetylation of essential virulence factors could lead to new targets for therapeutics against mycobacteria.
Topics: Humans; Animals; Virulence; Mycobacterium marinum; Acetylation; Mycobacterium tuberculosis; Bacterial Proteins; Virulence Factors; Acetyltransferases
PubMed: 37772840
DOI: 10.1128/mbio.00987-23 -
Microorganisms Sep 2023Antimicrobial peptides (AMPs) can directly kill Gram-positive bacteria, Gram-negative bacteria, mycobacteria, fungi, enveloped viruses, and parasites. At sublethal...
Antimicrobial peptides (AMPs) can directly kill Gram-positive bacteria, Gram-negative bacteria, mycobacteria, fungi, enveloped viruses, and parasites. At sublethal concentrations, some AMPs and also conventional antibiotics can stimulate bacterial response increasing their resilience, also called the hormetic response. This includes stimulation of growth, mobility, and biofilm production. Here, we describe the discovery of AMPs that stimulate the growth of certain mycobacteria. Peptide 14 showed a growth stimulating effect on (MTB), , subsp. (MAP), , and The effect was more pronounced at low bacterial inocula. The peptides induce a faster transition from the lag phase to the log phase and keep the bacteria longer in the log phase before entering stationary phase when compared to nontreated controls. In some cases, an increase in the division rate was observed. An initial screen using MAP and a collection of 75 peptides revealed 13 peptides with a hormetic effect. For MTB, a collection of 25 artificial peptides were screened and 13 were found to reduce the time to positivity (TTP) by at least 5%, improving growth. A screen of 43 naturally occurring peptides, 11 fragments of naturally occurring peptides and 5 designed peptides, all taken from the database APD3, identified a further 44 peptides that also lowered TTP by at least 5%. Lasioglossin LL-III (Bee) and Ranacyclin E (Frog) were the most active natural peptides, and the human cathelicidin LL37 fragment GF-17 and a porcine cathelicidin protegrin-1 fragment were the most active fragments of naturally occurring peptides. Peptide 14 showed growth-stimulating activity between 10 ng/mL and 10 µg/mL, whereas the stability-optimised Peptide 14D had a narrow activity range of 0.1-1 µg/mL. Peptides identified in this study are currently in commercial use to improve recovery and culture for the diagnostics of mycobacteria in humans and animals.
PubMed: 37764069
DOI: 10.3390/microorganisms11092225 -
Acta Dermato-venereologica Sep 2023
Topics: Humans; Trephining; Hand; Upper Extremity; High-Throughput Nucleotide Sequencing
PubMed: 37731212
DOI: 10.2340/actadv.v103.13360 -
Scientific Reports Sep 2023The β-lactamase of Mycobacterium tuberculosis, BlaC, hydrolyzes β-lactam antibiotics, hindering the use of these antibiotics for the treatment of tuberculosis....
The β-lactamase of Mycobacterium tuberculosis, BlaC, hydrolyzes β-lactam antibiotics, hindering the use of these antibiotics for the treatment of tuberculosis. Inhibitors, such as avibactam, can reversibly inhibit the enzyme, allowing for the development of combination therapies using both antibiotic and inhibitor. However, laboratory evolution studies using Escherichia coli resulted in the discovery of single amino acid variants of BlaC that reduce the sensitivity for inhibitors or show higher catalytic efficiency against antibiotics. Here, we tested these BlaC variants under more physiological conditions using the M. marinum infection model of zebrafish, which recapitulates hallmark features of tuberculosis, including the intracellular persistence of mycobacteria in macrophages and the induction of granuloma formation. To this end, the M. tuberculosis blaC gene was integrated into the chromosome of a blaC frameshift mutant of M. marinum. Subsequently, the resulting strains were used to infect zebrafish embryos in order to test the combinatorial effect of ampicillin and avibactam. The results show that embryos infected with an M. marinum strain producing BlaC show lower infection levels after treatment than untreated embryos. Additionally, BlaC K234R showed higher infection levels after treatment than those infected with bacteria producing the wild-type enzyme, demonstrating that the zebrafish host is less sensitive to the combinatorial therapy of β-lactam antibiotic and inhibitor. These findings are of interest for future development of combination therapies to treat tuberculosis.
Topics: Animals; Mycobacterium tuberculosis; Zebrafish; Mycobacterium marinum; beta-Lactamases; Tuberculosis; Ampicillin; Anti-Bacterial Agents; Escherichia coli
PubMed: 37717068
DOI: 10.1038/s41598-023-42152-8 -
Microbiology Resource Announcements Oct 2023The complete genome sequence of mycobacterial strain YM-3, isolated from cultured yellowtail in 1986, was determined. The strain was , a closely related subspecies of ,...
The complete genome sequence of mycobacterial strain YM-3, isolated from cultured yellowtail in 1986, was determined. The strain was , a closely related subspecies of , so the strain was isolated earlier than the first report of the subspecies in 2005.
PubMed: 37712690
DOI: 10.1128/MRA.00498-23 -
MBio Oct 2023Tuberculosis still remains a global burden and is one of the top infectious diseases from a single pathogen. , the causative agent, has perfected many ways to replicate...
Tuberculosis still remains a global burden and is one of the top infectious diseases from a single pathogen. , the causative agent, has perfected many ways to replicate and persist within its host. While mycobacteria induce vacuole damage to evade the toxic environment and eventually escape into the cytosol, the host recruits repair machineries to restore the MCV membrane. However, how lipids are delivered for membrane repair is poorly understood. Using advanced fluorescence imaging and volumetric correlative approaches, we demonstrate that this involves the recruitment of the endoplasmic reticulum (ER)-Golgi lipid transfer protein OSBP8 in the / system. Strikingly, depletion of OSBP8 affects lysosomal function accelerating mycobacterial growth. This indicates that an ER-dependent repair pathway constitutes a host defense mechanism against intracellular pathogens such as .
Topics: Humans; Vacuoles; Dictyostelium; Endoplasmic Reticulum; Mycobacterium marinum; Mycobacterium tuberculosis; Tuberculosis
PubMed: 37676004
DOI: 10.1128/mbio.00943-23 -
Respirology Case Reports Oct 2023is a ubiquitous water-borne non-tuberculous mycobacterial (NTM) pathogen. In humans, infections are acquired through direct inoculation of skin wounds and are almost...
is a ubiquitous water-borne non-tuberculous mycobacterial (NTM) pathogen. In humans, infections are acquired through direct inoculation of skin wounds and are almost exclusively localized to skin and soft tissues. Pulmonary infection with is extremely rare, and to our knowledge, invasive endobronchial disease has not been reported. Here, we present a case of a 71-year-old immunocompetent male surfer with invasive endotracheal granulomatous disease. The patient was successfully cured with a regimen of azithromycin 250 mg daily, ethambutol 900 mg (15 mg/kg) daily and rifampicin 600 mg daily for 12 months following culture conversion. This case highlights several important concepts: Firstly, infection, including invasive endobronchial infection, should be considered a rare cause of NTM pulmonary disease. Secondly, endotracheal infection can be successfully eradicated with this selected therapeutic regimen. Finally, the absence of . skin or soft-tissue infection in this patient, raises the possibility that human disease might also be acquired via inhalation of . contaminated water in rare circumstances.
PubMed: 37664419
DOI: 10.1002/rcr2.1211 -
BioRxiv : the Preprint Server For... Aug 2023Intracellular lipid inclusions (ILI) are triacylglyceride rich organelles produced by mycobacteria thought to serve as energy reservoirs. It is believed that ILI are...
Intracellular lipid inclusions (ILI) are triacylglyceride rich organelles produced by mycobacteria thought to serve as energy reservoirs. It is believed that ILI are formed as a result of a mediated transition from replicative growth to non-replicating persistence (NRP). ILI rich (Mtb) bacilli have been reported during infection and in sputum, establishing their importance in Mtb pathogenesis. Studies conducted in mycobacteria such as or lab Mtb strains have demonstrated ILI formation in the presence of hypoxic, nitric oxide, nutrient limitation, or low nitrogen stress, conditions believed to emulate the host environment within which Mtb resides. Here, we show that and clinical Mtb isolates make ILI during active replication in axenic culture independent of environmental stressors. By tracking ILI formation dynamics we demonstrate that ILI are quickly formed in the presence of fresh media or exogenous fatty acids but are rapidly depleted while bacteria are still actively replicating. We also show that the cell envelope is an alternate site for neutral lipid accumulation observed during stationary phase. In addition, we screen a panel of 60 clinical isolates and observe variation in ILI production during early log phase growth between and among Mtb lineages. Finally, we show that expression level does not strictly correlate with ILI accumulation in fresh clinical isolates. Taken together, our data provide evidence of an active ILI formation pathway in replicating mycobacteria cultured in the absence of stressors, suggesting a decoupling of ILI formation from NRP.
PubMed: 37609245
DOI: 10.1101/2023.08.10.552809 -
Cureus Jul 2023is a ubiquitous and opportunist agent that may cause infections related to water activities in humans. It causes mainly skin and soft tissue infections, and other...
is a ubiquitous and opportunist agent that may cause infections related to water activities in humans. It causes mainly skin and soft tissue infections, and other forms of presentation are uncommon. A 27-year-old man presented to the Emergency Department of a tertiary hospital due to a cervical foreign-body sensation that evolved into right cervical swelling and consumption symptoms. He was a waiter on a cruise in the Douro river. Weeks after the initial presentation, the diagnosis of infection was made by positive nucleic acid amplification tests (NAAT) in tissues obtained by excisional biopsy of cervical adenopathy. Treatment with rifampicin and clarithromycin was started. The symptoms improved, and there was a decrease in the adenopathy number and size. Although adenitis as initial presentation of the disease is rare, the identification of the agent by NAAT and favorable response to treatment supported the diagnosis.
PubMed: 37575752
DOI: 10.7759/cureus.41833 -
Indian Journal of Dermatology 2023
PubMed: 37529440
DOI: 10.4103/ijd.ijd_533_22