Mutations in ppe38 block PE-PGRS secretion and increase virulence of Mycobacterium tuberculosis

Louis S. Ates, Anzaan Dippenaar, Roy Ummels, Sander R. Piersma, Aniek D. van der Woude, Kim van der Kuij, Fabien le Chevalier, Dulce Mata-Espinosa, Jorge Barrios-Payán, Brenda Marquina-Castillo, Carolina Guapillo, Connie R. Jiménez, Arnab Pain, Edith N. G. Houben, Robin M. Warren, Roland Brosch, Rogelio Hernández-Pando, Wilbert Bitter

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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 1,2 . 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 3,4 . However, the role of these proteins remains largely elusive 1 . 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 5 . 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 6,7 .
Original languageEnglish
Pages (from-to)181-188
Number of pages8
JournalNature Microbiology
Issue number2
Early online date15 Jan 2018
Publication statusPublished - Feb 2018


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