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The type VII secretion system (T7SS) of secretes three substrate classes: Esx, Esp, and PE/PPE proteins, that play important roles in bacterial physiology and host interaction. Five subtypes of T7SS, namely ESX-1 to ESX-5, are present in . ESX-4 is the progenitor of T7SS but its function is not understood. We investigated the ESX-4 system in . We show that ESX-4 of does not secrete its cognate substrates, EsxT and EsxU, under the conditions tested. Paradoxically, the deletion of , an essential component of ESX-4, resulted in elevated secretion of protein substrates of ESX-1 and ESX-5. Consequently, the Δ mutant was more efficient in inducing actin cytoskeleton rearrangement, which led to enhanced phagocytosis by macrophages. Our results reveal an intimate crosstalk between the progenitor of T7SS and its more recent duplication and expansion, and provide new insight into the evolution of T7SS in mycobacteria.
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http://dx.doi.org/10.1016/j.isci.2021.103585 | DOI Listing |
mBio
September 2025
School of Life Sciences, University of Warwick, Coventry, United Kingdom.
The FtsEX-EnvC-AmiA/B system is a key component of the cell division machinery that directs breakage of the peptidoglycan layer during separation of daughter cells. Structural and mechanistic studies have shown that ATP binding by FtsEX in the cytoplasm drives periplasmic conformational changes in EnvC, which lead to the binding and activation of peptidoglycan amidases such as AmiA and AmiB. The FtsEX-EnvC amidase system is highly regulated to prevent cell lysis with at least two separate layers of autoinhibition that must be relieved to initiate peptidoglycan hydrolysis during division.
View Article and Find Full Text PDFPLoS Pathog
September 2025
Centre for Molecular Inflammation Research (CEMIR), Norwegian University of, Science and Technology (NTNU), Trondheim, Norway.
Drosophila melanogaster (Drosophila) is one of the most extensively studied animal models we have, with a broad, advanced, and organized research community. Yet, Drosophila has barely been exploited to understand the underlying mechanisms of mycobacterial infections, which cause some of the deadliest infectious diseases humans are currently battling. Here, we identified mycobacterial genes required for the pathogen's growth during Drosophila infection.
View Article and Find Full Text PDFSpatiotemporal environmental variation results in marked heterogeneity in bacterial infection progression and disease outcome, with vital consequences for treatment success. For the globally important pathogen (Mtb), while the pronounced intra-host spatial heterogeneity in lesion immune cell composition and phenotype has been well-described, the highly complex Mtb cell envelope has presented a particular challenge for the required equivalent insight into bacterial heterogeneity. Here, we develop hybridization chain reaction- fluorescence hybridization (HCR-FISH)-based methodology for Mtb mRNA visualization in the context of intact lung and lesion architecture.
View Article and Find Full Text PDFJ Immunother Cancer
September 2025
Center for Cancer Immunotherapy, La Jolla Institute for Immunology, La Jolla, California, USA
Background: CD4 T cells play a critical role in the positive and negative regulation of cellular immunity through the many functional subsets they comprise. The progressive growth of immunogenic tumors which nonetheless generate mutation-specific T cells suggests that effective immune control may be avoided or suppressed at the level of the neoantigen-specific CD4 T-cell response. Despite their importance, little is known about the ontogeny, architecture, and development of the CD4 NeoAg-specific repertoire induced by progressively growing tumor.
View Article and Find Full Text PDFJ Shoulder Elbow Surg
September 2025
Department of Orthopaedic Surgery, University of California Davis, Sacramento, CA, USA. Electronic address:
Background: Computed tomography (CT) is routinely used for preoperative planning in shoulder arthroplasty. However, this practice exposes patients to ionizing radiation. This study evaluates the potential lifetime cancer risks of conventional and low-dose shoulder CT protocols.
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