A mycobacterial virulence gene cluster extending RD1 is required for cytolysis, bacterial spreading and ESAT‐6 secretion

Gao, Lian-Yong; Guo, Su; McLaughlin, Bryant; Morisaki, Hiroshi; Engel, Joanne N.; Brown, Eric J.

doi:10.1111/j.1365-2958.2004.04261.x

Cited by 372 publications

(561 citation statements)

References 57 publications

Supporting

Mentioning

523

Contrasting

Unclassified

Order By: Relevance

“…In the ESX-1 mutant the detection levels of MmPE35 were lower than in the WT and ESX-5 mutant strains. As discussed above for PE25/PPE41, this is likely due to MmPE35's instability in the absence of a functional ESX-1 system (5,11,13,33). These results show that MmPE35 is indeed secreted via ESX-1.…”

Section: Esx-5 Secretion Of M Tuberculosis Lipy Depends On a Similarsupporting

confidence: 51%

“…This secretion defect was not accompanied by an increase in cellular levels of PE25 and PPE41. This phenomenon is often observed for ESX-1 and ESX-5 substrates and indicates that the stability of the substrates depends on the presence of the T7S systems in the bacterial cell (5,11,13,33). PPE41 was detected in two forms, a 25-kDa band, which represents full-length PPE41, and a smaller form of ∼19 kDa, which probably represents degraded PPE41 (20).…”

Section: Resultsmentioning

confidence: 98%

“…Such a system has recently been identified in mycobacteria and other bacteria with similar cell envelope organization and is now known as the ESX or type VII secretion (T7S) pathway (4). This pathway is responsible for secretion of multiple proteins that lack classical signal peptides in mycobacteria (5)(6)(7)(8).…”

mentioning

confidence: 99%

See 2 more Smart Citations

General secretion signal for the mycobacterial type VII secretion pathway

Daleke

Ummels

Bawono³

et al. 2012

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

183

224

View full text Add to dashboard Cite

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.

show abstract

Section: Esx-5 Secretion Of M Tuberculosis Lipy Depends On a Similarsupporting

confidence: 51%

Section: Resultsmentioning

confidence: 98%

See 1 more Smart Citation

General secretion signal for the mycobacterial type VII secretion pathway

Daleke

Ummels

Bawono³

et al. 2012

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

183

224

View full text Add to dashboard Cite

show abstract

“…Additional work suggests the RD1-encoded proteins may disrupt host cell membranes. In M. tuberculosis, these proteins may be required for lysis of infected cells (13) and cell-to-cell spread (16), whereas, in M. marinum, RD1 is needed for efficient bacterial escape from the phagosome (17).…”

Section: Esat-6 Protein ͉ Mycobacterium Tuberculosis ͉ Virulence Factormentioning

confidence: 99%

Mutually dependent secretion of proteins required for mycobacterial virulence

Fortune

Jaeger²,

Sarracino³

et al. 2005

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

359

410

View full text Add to dashboard Cite

The ESX-1 locus is a region critical for full virulence in Mycobacterium tuberculosis, which encodes two secreted proteins as well as other genes involved in their secretion. The mechanism of secretion of the two proteins, ESAT-6 and CFP-10, and their function remain unknown. Using proteomic methods to search for additional proteins secreted by the ESX-1 locus, we discovered that a protein encoded by a chromosomally unlinked gene, espA, is also secreted by strains that contain the ESX-1 locus but not by strains with ESX-1 deletions. Mutations in individual ESX-1 genes, including those that encode ESAT-6 and CFP-10, were found to block EspA secretion. Surprisingly, mutants that lack espA reciprocally failed to secrete ESAT-6 and CFP-10 and were as attenuated as ESX-1 mutants in virulence assays. The results indicate that secretion of these proteins, which are each critical for virulence of pathogenic mycobacteria, is mutually dependent. The results further suggest that discerning the nature of the interaction and the structure of macromolecular complexes will provide insights into both an alternative mechanism of protein secretion and mycobacterial virulence.ESAT-6 protein ͉ Mycobacterium tuberculosis ͉ virulence factor I nteractions between bacterial pathogens and their hosts occur at the surface of cells. Many pathogenic bacteria secrete proteins involved in virulence (1). These proteins often interfere with normal host defenses and allow bacteria to survive and multiply. Strikingly, many of these virulence factors are secreted by nonclassical secretory systems that, in some cases, facilitate translocation of proteins across host cell membranes (2, 3).During the evolution of Mycobacterium bovis Bacille Calmette-Guérin (BCG), the attenuated bacillus widely used as vaccine against tuberculosis, a major deletion removed a set of nine ORFs (4). Similar deletions are found in Mycobacterium microti (5) and the Dassie bacillus (6), other relatively avirulent mycobacteria. The BCG deletion, known as RD1, includes two genes that encode the abundantly secreted proteins, ESAT-6 and CFP-10. The RD1 deletion encompasses most but not all of a larger, 15-gene region known as ESX-1 (7), which is hypothesized to encode an alternative secretory system (8, 9).The proteins encoded by the ESX-1 locus clearly play an important role in virulence. The secreted proteins encoded within the locus are potent T cell antigens (7, 10, 11). More significantly, Mycobacterium tuberculosis strains with RD1 deletions are far less virulent in mice than strains that are otherwise isogenic (12-14). They replicate poorly and cause less pathology in both immunocompetent and immunocompromised mice, although the latter ultimately succumb to infection. RD1-deleted strains of Mycobacterium marinum elicit only very modest macrophage aggregation and granuloma formation in zebrafish (15). Additional work suggests the RD1-encoded proteins may disrupt host cell membranes. In M. tuberculosis, these proteins may be required for lysis of infected cells (13) and c...

show abstract

“…For instance, comparative analysis has demonstrated conservation of biochemical pathways and a secretory system important for full virulence of M. tuberculosis (7,10). This indicates that genetic elements and the proteins they encode that exist in other mycobacteria either serve an important function in M. tuberculosis pathogenicity or have evolved a specific role in M. tuberculosis complex organisms.…”

mentioning

confidence: 99%

Evolution of the Mycobacterial SigK Regulon

2008

View full text Add to dashboard Cite

Previous studies have established that members of the Mycobacterium tuberculosis complex exhibit variable production of the antigenic proteins MPT70 and MPT83 due to mutations in their positive regulator, SigK (sigma factor K), and their negative regulator, RskA (regulator of sigma K). To further understand this highly specific SigK-controlled regulon, we have undertaken evolutionary studies to determine the presence of homologues of SigK-regulated genes in other organisms and to predict its transcriptional network. Evolutionary analysis indicates that the positive and negative regulators are conserved across many organisms, but that the genes under their control are variable. Moreover, the addition, loss, and movement of various genes in the mpt70/83 locus suggest that these genes are unlikely to be cotranscribed. To test predictions from sequence analysis, we have used promoter luciferase fusions and Northern blots to show that the majority of genes in this locus have their own promoters, of which a subset are SigK regulated (mpt83, dipZ, mpt70, and Rv0449c). Next, we have shown that the intracellular inducibility of mpt70 and mpt83 is a conserved property, shared between M. tuberculosis and Mycobacterium marinum. In addition, we have shown that SigK and RskA from an environmental mycobacterium isolate (M. gilvum PYR-GCK) complemented the regulatory activity of M. tuberculosis ⌬sigK rskA. Together, our data indicate that the regulatory system SigK/RskA is conserved across the Mycobacterium genus, whereas the regulon under its control varies considerably across species.Mycobacterium tuberculosis is an extremely successful pathogen of humans, infecting an estimated one-third of the world's population. This capacity to persist in the host, despite the dynamic alterations effected by the host immune response, testifies to an evolved capacity of the organism to regulate its genetic expression to the conditions encountered during infection. Indeed, a number of studies have demonstrated that disruption of M. tuberculosis regulatory elements, such as sigma factors, results in reduced virulence in experimental models (21,28,30).The determination of genomic sequences for a number of nonpathogenic mycobacteria has revealed that homologues of many genes, including regulatory elements, are often present in organisms that are not virulent to humans. For instance, comparative analysis has demonstrated conservation of biochemical pathways and a secretory system important for full virulence of M. tuberculosis (7,10). This indicates that genetic elements and the proteins they encode that exist in other mycobacteria either serve an important function in M. tuberculosis pathogenicity or have evolved a specific role in M. tuberculosis complex organisms. As a number of predicted regulatory elements are also conserved between environmental mycobacteria and M. tuberculosis, it follows that an evolutionary analysis may guide predictions about the origins of such elements, the transcriptional networks they control, and the stimuli that...

show abstract

A mycobacterial virulence gene cluster extending RD1 is required for cytolysis, bacterial spreading and ESAT‐6 secretion

Cited by 372 publications

References 57 publications

General secretion signal for the mycobacterial type VII secretion pathway

General secretion signal for the mycobacterial type VII secretion pathway

Mutually dependent secretion of proteins required for mycobacterial virulence

Evolution of the Mycobacterial SigK Regulon

Contact Info

Product

Resources

About