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Mutations in ppe38 block PE_PGRS secretion and increase virulence of Mycobacterium tuberculosis

Abstract : Mycobacterium tuberculosis requires a large number of secreted and exported proteins for its virulence, immune modulation and nutrient uptake. Most of these proteins are transported by the different type VII secretion systems. The most recently evolved type VII secretion system, ESX-5, secretes dozens of substrates belonging to the PE and PPE families, which are named for conserved proline and glutamic acid residues close to the amino terminus. However, the role of these proteins remains largely elusive. Here, we show that mutations of ppe38 completely block the secretion of two large subsets of ESX-5 substrates, that is, PPE-MPTR and PE_PGRS, together comprising >80 proteins. Importantly, hypervirulent clinical M. tuberculosis strains of the Beijing lineage have such a mutation and a concomitant loss of secretion. Restoration of PPE38-dependent secretion partially reverted the hypervirulence phenotype of a Beijing strain, and deletion of ppe38 in moderately virulent M. tuberculosis increased virulence. This indicates that these ESX-5 substrates have an important role in virulence attenuation. Phylogenetic analysis revealed that deletion of ppe38 occurred at the branching point of the 'modern' Beijing sublineage and is shared by Beijing outbreak strains worldwide, suggesting that this deletion may have contributed to their success and global distribution.
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https://hal-pasteur.archives-ouvertes.fr/pasteur-02046016
Contributor : Laurence Langlais <>
Submitted on : Friday, February 22, 2019 - 2:38:16 PM
Last modification on : Monday, January 13, 2020 - 5:08:19 PM

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Louis Ates, Anzaan Dippenaar, Roy Ummels, Sander Piersma, Aniek van der Woude, et al.. Mutations in ppe38 block PE_PGRS secretion and increase virulence of Mycobacterium tuberculosis. Nature Microbiology, Nature Publishing Group, 2018, 3 (2), pp.181-188. ⟨10.1038/s41564-017-0090-6⟩. ⟨pasteur-02046016⟩

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