Transcriptional profile of Mycobacterium tuberculosis espL deletion mutant
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ABSTRACT: The ESX-1, type VII, secretion system represents the major virulence determinant of Mycobacterium tuberculosis. The ESX-1 cluster comprises approximately twenty genes and encodes a specialized secretion apparatus, which releases effectors into the extracellular milieu. The goal of this study is to understand the role of EspL. We show that EspL, a protein of 115 amino acids, is essential for mediating ESX-1-dependent virulence and for stabilization of EspE, EspF and EspH protein levels. Indeed, an espL knock-out mutant was unable to replicate intracellularly, secrete ESX-1 substrates or stimulate innate cytokine production. Moreover, loss of EspL also leads to downregulation in M. tuberculosis of WhiB6, a redox-sensitive transcriptional activator of ESX-1 genes.
Project description:The ESX-1, type VII, secretion system represents the major virulence determinant of Mycobacterium tuberculosis, one of the most successful intracellular pathogens. Here, by combining genetic and high-throughput approaches, we show that EspL, a protein of 115 amino acids, is essential for mediating ESX-1-dependent virulence and for stabilization of EspE, EspF and EspH protein levels. Indeed, an espL knock-out mutant was unable to replicate intracellularly, secrete ESX-1 substrates or stimulate innate cytokine production. Moreover, proteomic studies detected greatly reduced amounts of EspE, EspF and EspH in the espL mutant as compared to the wild type strain, suggesting a role for EspL as a chaperone. The latter conclusion was further supported by discovering that EspL interacts with EspD, which was previously demonstrated to stabilize the ESX-1 substrates and effector proteins, EspA and EspC. Moreover, loss of EspL also leads to downregulation in M. tuberculosis of WhiB6, a redox-sensitive transcriptional activator of ESX-1 genes. Overall, our data highlight the importance of a so-far overlooked, though conserved, component of the ESX-1 secretion system and begin to delineate the role played by EspE, EspF and EspH in virulence and host-pathogen interaction.
Project description:The ESX-1, type VII, secretion system represents the major virulence determinant of Mycobacterium tuberculosis, one of the most successful intracellular pathogens. Here, by combining genetic and high-throughput approaches, we investigate the effect of espB on the secretion of ESX-1 components and other proetins, as well as virulence.
Project description:The ESX-1, type VII, secretion system represents the major virulence determinant of Mycobacterium tuberculosis, one of the most successful intracellular pathogens. Here we study the proteme of various ESX-1 knock-out mutants.
Project description:Mycobacterium tuberculosis is a slow-growing intracellular bacterium with the ability to induce host cell death and persist indefinitely in the human body. This pathogen uses the specialised ESX-1 secretion system to secrete virulence factors and potent immunogenic effectors required for disease progression. ESX-1 is a multi-subunit apparatus with a membrane complex that is predicted to form a pore in the cytoplasmic membrane. In M. tuberculosis this complex is made of five membrane proteins: EccB1, EccCa1, EccCb1, EccD1, EccE1. In this study, we have characterised the membrane component EccE1, and we found that deletion of eccE1 leads to disruption of ESX-1 secretion and attenuation of M. tuberculosis ex vivo.
Project description:Mycobacterium tuberculosis relies on the ESX-1 secretion system for survival, multiplication in and escape from macrophages. In this work we investigate the role of the EspB protein, encoded within the esx-1 gene cluster, in virulence and ESX-1 substrate secretion in M. tuberculosis H37Rv. Genetic, proteomic and immunological data show that, contrary to previous reports, an espB knock-out mutant is only partially attenuated in ex vivo infection models, where EsxA, EsxB and EspC antigen presentation is not affected, and secretes the major virulence factor EsxA. Additionally, we demonstrate that EspB does not require an intact and functional ESX-1 apparatus for being secreted in H37Rv and in M. bovis BCG, as opposed to other strains such as CDC1551 and Erdman, thereby suggesting that other ESX systems may be involved in the process. Overall our findings highlight unexplored differences in the secretion profiles of various mycobacterial strains and underscore the plasticity of ESX-dependent secretion in mycobacteria.
Project description:Mycobacterium tuberculosis, a pathogen of global importance, utilizes the ESX-1 protein secretion system to export virulence factors that disarm host macrophages. Although this secretory pathway is critical for virulence, how ESX-1 is regulated is completely unknown. Here we show that EspR (Rv3849) is a key regulator of ESX-1. EspR activates transcription of an operon that includes three ESX-1 components, Rv3616c-Rv3614c, whose expression in turn promotes secretion of ESX-1 substrates. Keywords: Strain comparison
Project description:Mycobacterium tuberculosis, a pathogen of global importance, utilizes the ESX-1 protein secretion system to export virulence factors that disarm host macrophages. Although this secretory pathway is critical for virulence, how ESX-1 is regulated is completely unknown. Here we show that EspR (Rv3849) is a key regulator of ESX-1. EspR activates transcription of an operon that includes three ESX-1 components, Rv3616c-Rv3614c, whose expression in turn promotes secretion of ESX-1 substrates. Keywords: Strain comparison
Project description:Mycobacterium tuberculosis, a pathogen of global importance, utilizes the ESX-1 protein secretion system to export virulence factors that disarm host macrophages. Although this secretory pathway is critical for virulence, how ESX-1 is regulated is completely unknown. Here we show that EspR (Rv3849) is a key regulator of ESX-1. EspR activates transcription of an operon that includes three ESX-1 components, Rv3616c-Rv3614c, whose expression in turn promotes secretion of ESX-1 substrates. Keywords: Strain comparison
Project description:Mycobacterium tuberculosis, a pathogen of global importance, utilizes the ESX-1 protein secretion system to export virulence factors that disarm host macrophages. Although this secretory pathway is critical for virulence, how ESX-1 is regulated is completely unknown. Here we show that EspR (Rv3849) is a key regulator of ESX-1. EspR activates transcription of an operon that includes three ESX-1 components, Rv3616c-Rv3614c, whose expression in turn promotes secretion of ESX-1 substrates. Keywords: Strain comparison
Project description:These data show that WhiB6 is required for the secretion-dependent regulation of ESX-1 substrates and ESX-1 substrates are regulated independently from the structural components, both during infection and as a result of active secretion.