Functional Dissection of the PE Domain Responsible for Translocation of PE_PGRS33 across the Mycobacterial Cell Wall

Cascioferro, Alessandro; Daleke, Maria H.; Ventura, Marcello; Donà, Valentina; Delogu, Giovanni; Palù, Giorgio; Bitter, Wilbert; Manganelli, Riccardo

doi:10.1371/journal.pone.0027713

Cited by 45 publications

(64 citation statements)

References 30 publications

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“…It is thus possible that system specificity results from a conformational signal, which could be located in another part of the PE protein. Indeed, analysis of the secretion of another ESX-5 substrate, PE_PGRS33, showed that this protein requires the first 30 residues of its PE domain for secretion (43). It is also possible that the specificity signal is located in the PPE partner protein or that it is formed by a combination of parts of the PE/PPE complex.…”

Section: Discussionmentioning

confidence: 99%

General secretion signal for the mycobacterial type VII secretion pathway

Daleke

Ummels

Bawono³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

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Mycobacterial pathogens use specialized type VII secretion (T7S) systems to transport crucial virulence factors across their unusual cell envelope into infected host cells. These virulence factors lack classical secretion signals and the mechanism of substrate recognition is not well understood. Here we demonstrate that the model T7S substrates PE25/PPE41, which form a heterodimer, are targeted to the T7S pathway ESX-5 by a signal located in the C terminus of PE25. Site-directed mutagenesis of residues within this C terminus resulted in the identification of a highly conserved motif, i.e., YxxxD/E, which is required for secretion. This motif was also essential for the secretion of LipY, another ESX-5 substrate. Pathogenic mycobacteria have several different T7S systems and we identified a PE protein that is secreted by the ESX-1 system, which allowed us to compare substrate recognition of these two T7S systems. Surprisingly, this ESX-1 substrate contained a C-terminal signal functionally equivalent to that of PE25. Exchange of these C-terminal secretion signals between the PE proteins restored secretion, but each PE protein remained secreted via its own ESX secretion system, indicating that an additional signal(s) provides system specificity. Remarkably, the YxxxD/E motif was also present in and required for efficient secretion of the ESX-1 substrates CFP-10 and EspB. Therefore, our data show that the YxxxD/E motif is a general secretion signal that is present in all known mycobacterial T7S substrates or substrate complexes.

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Section: Discussionmentioning

confidence: 99%

General secretion signal for the mycobacterial type VII secretion pathway

Daleke

Ummels

Bawono³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

178

224

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“…There is evidence that some PE and PPE proteins are exported to the bacterial cell surface or extracellular milieu in an ESX-dependent manner (3)(4)(5)(6). ESX-dependent export requires specific sequences within the PE or PPE domain (7,8), including a recently described YxxxD/E ESX secretion targeting motif located near the C terminus of the ϳ110-amino-acid PE domain (9).…”

mentioning

confidence: 99%

“…Among this set of genes, there were several that encode PE and PPE proteins. Of the PE and PPE proteins that have been characterized to date, many are localized to the mycobacterial cell wall (3,7,8,(34)(35)(36). We hypothesized that the overexpression of cell wall-localized PE and/or PPE proteins in the ⌬pstA1 mutant sensitize these bacteria to stress by subtly altering the architecture or permeability of the cell wall.…”

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confidence: 99%

Mycobacterium tuberculosis Resists Stress by Regulating PE19 Expression

et al. 2016

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cMycobacterium tuberculosis requires the phosphate-sensing signal transduction system Pst/SenX3-RegX3 to resist host immune responses. A ⌬pstA1 mutant lacking a Pst phosphate uptake system component is hypersensitive to diverse stress conditions in vitro and is attenuated in vivo due to constitutive expression of the phosphate starvation-responsive RegX3 regulon. Transcriptional profiling of the ⌬pstA1 mutant revealed aberrant expression of certain pe and ppe genes. PE and PPE proteins, defined by conserved N-terminal domains containing Pro-Glu (PE) or Pro-Pro-Glu (PPE) motifs, account for a substantial fraction of the M. tuberculosis genome coding capacity, but their functions are largely uncharacterized. Because some PE and PPE proteins localize to the cell wall, we hypothesized that overexpression of these proteins sensitizes M. tuberculosis to stress by altering cell wall integrity. To test this idea, we deleted pe and ppe genes that were overexpressed by ⌬pstA1 bacteria. Deletion of a single pe gene, pe19, suppressed hypersensitivity of the ⌬pstA1 mutant to both detergent and reactive oxygen species. Ethidium bromide uptake assays revealed increased envelope permeability of the ⌬pstA1 mutant that was dependent on PE19. The replication defect of the ⌬pstA1 mutant in NOS2 ؊/؊ mice was partially reversed by deletion of pe19, suggesting that increased membrane permeability due to PE19 overexpression sensitizes M. tuberculosis to host immunity. Our data indicate that PE19, which comprises only a 99-amino-acid PE domain, has a unique role in the permeability of the M. tuberculosis envelope that is regulated to resist stresses encountered in the host. O ver 15 years ago, the novel PE and PPE protein families were identified in the complete genome sequence of Mycobacterium tuberculosis; together, these proteins represent over 7% of the genome coding capacity (1). Despite the attention placed on these protein families, their functions remain largely uncharacterized. PE and PPE proteins are defined by conserved N-terminal domains of ϳ110 or ϳ180 amino acids that contain Pro-Glu (PE) or Pro-Pro-Glu (PPE) sequence motifs, respectively (1). Although PE and PPE proteins can be identified in the genomes of all sequenced members of the Mycobacterium genus, their expansion into large multiprotein families is restricted to the slow-growing pathogenic mycobacterial species, including M. tuberculosis, and associated with the expansion of the ESX type VII secretion systems (2). There is evidence that some PE and PPE proteins are exported to the bacterial cell surface or extracellular milieu in an ESX-dependent manner (3-6). ESX-dependent export requires specific sequences within the PE or PPE domain (7, 8), including a recently described YxxxD/E ESX secretion targeting motif located near the C terminus of the ϳ110-amino-acid PE domain (9).The 99 PE proteins and 69 PPE proteins encoded by the M. tuberculosis H37Rv genome can be further divided into subfamilies based on C-terminal sequence motifs (2). The PE_PGRS (polymorphic GC-...

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“…Localization of components of other ESX systems has not been determined. However, the Rv1818c (PE_PGRS33) ESX-5 substrate has been localized to the mycobacterial pole, which may indicate that the ESX-5 system is also polar (61,118). The polar localization of ESX-1 systems and cell wall biogenesis proteins may indicate that lipid or cell wall processes play a role in ESX-1 localization and assembly.…”

Section: Cell Wall Synthesis and Esx Systemsmentioning

confidence: 99%

“…The ESX-5 system, which is restricted to slow-growing mycobacterial species, likely promotes the uptake of nutrients essential for mycobacterial survival in the phagocyte (27,50,57,58). Relative to the ESX-1 system, the ESX-5 system secretes a large number of proline-glutamate/proline-proline-glutamate (PE/PPE) proteins which promote virulence (51,(59)(60)(61)(62). ESX-5 is also unique in that it is a modular system; accessory components outside the conserved locus promote the secretion of a specific subset of ESX-5 substrates (36,63).…”

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confidence: 99%

Esx Systems and the Mycobacterial Cell Envelope: What's the Connection?

Bosserman

Champion

2017

J Bacteriol

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Mycobacterial 6-kDa early secreted antigenic target (ESAT-6) system (ESX) exporters transport proteins across the cytoplasmic membrane. Many proteins transported by ESX systems are then translocated across the mycobacterial cell envelope and secreted from the cell. Although the mechanism underlying protein transport across the mycolate outer membrane remains elusive, the ESX systems are closely connected with and localize to the cell envelope. Links between ESX-associated proteins, cell wall synthesis, and the maintenance of cell envelope integrity have been reported. Genes encoding the ESX systems and those required for biosynthesis of the mycobacterial envelope are coregulated. Here, we review the interplay between ESX systems and the mycobacterial cell envelope.

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Functional Dissection of the PE Domain Responsible for Translocation of PE_PGRS33 across the Mycobacterial Cell Wall

Cited by 45 publications

References 30 publications

General secretion signal for the mycobacterial type VII secretion pathway

General secretion signal for the mycobacterial type VII secretion pathway

Mycobacterium tuberculosis Resists Stress by Regulating PE19 Expression

Esx Systems and the Mycobacterial Cell Envelope: What's the Connection?

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