<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity

ABSTRACT Mycobacterium tuberculosis releases membrane vesicles (MV) that modulate host immune responses and aid in iron acquisition, although they may have additional unappreciated functions. MV production appears to be a regulated process, but virR remains the only characterized genetic regulator o...

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Autores principales:	Dylan W. White, Sarah R. Elliott, Evan Odean, Lynne T. Bemis, Anna D. Tischler
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2018
Materias:	ESX secretion type VII secretion lipoproteins tuberculosis vesicle Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/04b4f4cab5884b46b196e6da5e1d5583
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spelling	oai:doaj.org-article:04b4f4cab5884b46b196e6da5e1d55832021-11-15T16:00:26Z<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity10.1128/mBio.00778-182150-7511https://doaj.org/article/04b4f4cab5884b46b196e6da5e1d55832018-07-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00778-18https://doaj.org/toc/2150-7511ABSTRACT Mycobacterium tuberculosis releases membrane vesicles (MV) that modulate host immune responses and aid in iron acquisition, although they may have additional unappreciated functions. MV production appears to be a regulated process, but virR remains the only characterized genetic regulator of vesiculogenesis. Here, we present data supporting a role for the M. tuberculosis Pst/SenX3-RegX3 signal transduction system in regulating MV production. Deletion of pstA1, which encodes a transmembrane component of the phosphate-specific transport (Pst) system, causes constitutive activation of the SenX3-RegX3 two-component system, leading to increased protein secretion via the specialized ESX-5 type VII secretion system. Using proteomic mass spectrometry, we identified several additional proteins hyper-secreted by the ΔpstA1 mutant, including LpqH, an MV-associated lipoprotein. Nanoparticle tracking analysis revealed a 15-fold increase in MV production by the ΔpstA1 mutant. Both hyper-secretion of LpqH and increased MV release required RegX3 but were independent of VirR, suggesting that Pst/SenX3-RegX3 controls MV release by a novel mechanism. Prior proteomic analysis identified ESX-5 substrates associated with MV. We therefore hypothesized that MV release requires ESX-5 activity. We constructed strains that conditionally express eccD5, which encodes the predicted ESX-5 transmembrane channel. Upon EccD5 depletion, we observed reduced secretion of the ESX-5 substrates EsxN and PPE41, but MV release was unaffected. Our data suggest that ESX-5 does not affect vesicle production and imply that further characterization of the Pst/SenX3-RegX3 regulon might reveal novel mechanisms of M. tuberculosis vesicle biogenesis. IMPORTANCE In Gram-negative bacteria, MV derived from the outer membrane have diverse functions in bacterial physiology and pathogenesis, and several factors regulating their production have been identified. Though Gram-positive bacteria and mycobacteria that lack an outer membrane also produce vesicles with described roles in pathogenesis, the mechanisms of MV biogenesis in these organisms remain poorly characterized. Defining mechanisms of MV biogenesis might yield significant insights into the importance of MV production during infection. In M. tuberculosis, only a single genetic element, virR, is known to regulate MV production. Our work reveals that the Pst/SenX3-RegX3 signal transduction system is a novel regulator of MV biogenesis that controls MV production by a mechanism that is independent of both VirR and activation of the specialized ESX-5 protein secretion system. Understanding which genes in the RegX3 regulon cause increased MV production might reveal novel molecular mechanisms of MV release.Dylan W. WhiteSarah R. ElliottEvan OdeanLynne T. BemisAnna D. TischlerAmerican Society for MicrobiologyarticleESX secretiontype VII secretionlipoproteinstuberculosisvesicleMicrobiologyQR1-502ENmBio, Vol 9, Iss 3 (2018)
institution	DOAJ
collection	DOAJ
language	EN
topic	ESX secretion type VII secretion lipoproteins tuberculosis vesicle Microbiology QR1-502
spellingShingle	ESX secretion type VII secretion lipoproteins tuberculosis vesicle Microbiology QR1-502 Dylan W. White Sarah R. Elliott Evan Odean Lynne T. Bemis Anna D. Tischler <italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity
description	ABSTRACT Mycobacterium tuberculosis releases membrane vesicles (MV) that modulate host immune responses and aid in iron acquisition, although they may have additional unappreciated functions. MV production appears to be a regulated process, but virR remains the only characterized genetic regulator of vesiculogenesis. Here, we present data supporting a role for the M. tuberculosis Pst/SenX3-RegX3 signal transduction system in regulating MV production. Deletion of pstA1, which encodes a transmembrane component of the phosphate-specific transport (Pst) system, causes constitutive activation of the SenX3-RegX3 two-component system, leading to increased protein secretion via the specialized ESX-5 type VII secretion system. Using proteomic mass spectrometry, we identified several additional proteins hyper-secreted by the ΔpstA1 mutant, including LpqH, an MV-associated lipoprotein. Nanoparticle tracking analysis revealed a 15-fold increase in MV production by the ΔpstA1 mutant. Both hyper-secretion of LpqH and increased MV release required RegX3 but were independent of VirR, suggesting that Pst/SenX3-RegX3 controls MV release by a novel mechanism. Prior proteomic analysis identified ESX-5 substrates associated with MV. We therefore hypothesized that MV release requires ESX-5 activity. We constructed strains that conditionally express eccD5, which encodes the predicted ESX-5 transmembrane channel. Upon EccD5 depletion, we observed reduced secretion of the ESX-5 substrates EsxN and PPE41, but MV release was unaffected. Our data suggest that ESX-5 does not affect vesicle production and imply that further characterization of the Pst/SenX3-RegX3 regulon might reveal novel mechanisms of M. tuberculosis vesicle biogenesis. IMPORTANCE In Gram-negative bacteria, MV derived from the outer membrane have diverse functions in bacterial physiology and pathogenesis, and several factors regulating their production have been identified. Though Gram-positive bacteria and mycobacteria that lack an outer membrane also produce vesicles with described roles in pathogenesis, the mechanisms of MV biogenesis in these organisms remain poorly characterized. Defining mechanisms of MV biogenesis might yield significant insights into the importance of MV production during infection. In M. tuberculosis, only a single genetic element, virR, is known to regulate MV production. Our work reveals that the Pst/SenX3-RegX3 signal transduction system is a novel regulator of MV biogenesis that controls MV production by a mechanism that is independent of both VirR and activation of the specialized ESX-5 protein secretion system. Understanding which genes in the RegX3 regulon cause increased MV production might reveal novel molecular mechanisms of MV release.
format	article
author	Dylan W. White Sarah R. Elliott Evan Odean Lynne T. Bemis Anna D. Tischler
author_facet	Dylan W. White Sarah R. Elliott Evan Odean Lynne T. Bemis Anna D. Tischler
author_sort	Dylan W. White
title	<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity
title_short	<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity
title_full	<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity
title_fullStr	<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity
title_full_unstemmed	<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity
title_sort	<italic toggle="yes">mycobacterium tuberculosis</italic> pst/senx3-regx3 regulates membrane vesicle production independently of esx-5 activity
publisher	American Society for Microbiology
publishDate	2018
url	https://doaj.org/article/04b4f4cab5884b46b196e6da5e1d5583
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<italic toggle="yes">Mycobacterium tuberculosis</italic> Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity

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