Mycobacterial Pan-Genome Analysis Suggests Important Role of Plasmids in the Radiation of Type VII Secretion Systems

Type VII secretion systems (T7SS) have been identified in Actinobacteria and Firmicutes and have been shown to secrete effector proteins with functions in virulence, host toxicity, and/or interbacterial killing in a few genera. Bioinformatic analysis indicates that isolates of Group B Streptococcus (GBS) encode at least four distinct subtypes of T7SS machinery, three of which encode adjacent putative T7SS effectors with WXG and LXG motifs. However, the function of T7SS in GBS pathogenesis is unknown. Here we assessed the role of the most abundant GBS T7SS subtype during GBS pathogenesis. In a murine model of hematogenous meningitis, mice infected with GBS lacking a functional T7SS or lacking the secreted WXG100 effector EsxA exhibited less mortality, lower bacterial burdens in tissues, and decreased inflammation in the brain compared to mice infected with the parental GBS strain. We further showed that this T7SS induces cytotoxicity in brain endothelium and that EsxA contributes to these cytotoxicity phenotypes in a WXG motif-dependent manner. Finally, we determined that EsxA is a pore-forming protein, thus demonstrating the first role for a non-mycobacterial EsxA homolog in pore formation. This work reveals the importance of a T7SS in host–GBS interactions and has implications for T7SS effector function in other Gram-positive bacteria.

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WhiB5, a Transcriptional Regulator That Contributes to Mycobacterium tuberculosis Virulence and Reactivation

Infection and Immunity ◽

10.1128/iai.06328-11 ◽

2012 ◽

Vol 80 (9) ◽

pp. 3132-3144 ◽

Cited By ~ 35

Author(s):

Stefano Casonato ◽

Axel Cervantes Sánchez ◽

Hirohito Haruki ◽

Monica Rengifo González ◽

Roberta Provvedi ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Chronic Infection ◽

Null Mutant ◽

Wild Type ◽

Secretion Systems ◽

Content Type ◽

Type Vii Secretion ◽

Expression Of Genes ◽

Genes Encoding

ABSTRACTThe proteins belonging to the WhiB superfamily are small global transcriptional regulators typical of actinomycetes. In this paper, we characterize the role of WhiB5, aMycobacterium tuberculosisprotein belonging to this superfamily. A null mutant was constructed inM. tuberculosisH37Rv and was shown to be attenuated during both progressive and chronic mouse infections. Mice infected with the mutant had smaller bacillary burdens in the lungs but a larger inflammatory response, suggesting a role of WhiB5 in immunomodulation. Most interestingly, thewhiB5mutant was not able to resume growth after reactivation from chronic infection, suggesting that WhiB5 controls the expression of genes involved in this process. The mutant was also more sensitive than the wild-type parental strain toS-nitrosoglutathione (GSNO) and was less metabolically active following prolonged starvation, underscoring the importance of GSNO and starvation in development and maintenance of chronic infection. DNA microarray analysis identified 58 genes whose expression is influenced by WhiB5, includingsigM, encoding an alternative sigma factor, and genes encoding the constituents of two type VII secretion systems, namely, ESX-2 and ESX-4.

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Role of Metal-Dependent Regulation of ESX-3 Secretion in Intracellular Survival of Mycobacterium tuberculosis

Infection and Immunity ◽

10.1128/iai.00197-16 ◽

2016 ◽

Vol 84 (8) ◽

pp. 2255-2263 ◽

Cited By ~ 16

Author(s):

Emir Tinaztepe ◽

Jun-Rong Wei ◽

Jenelle Raynowska ◽

Cynthia Portal-Celhay ◽

Victor Thompson ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Cell Envelope ◽

Bacterial Pathogen ◽

Transcriptional Response ◽

Secretion Systems ◽

Content Type ◽

Type Vii Secretion ◽

Significant Difference ◽

Iron And Zinc

More people die every year fromMycobacterium tuberculosisinfection than from infection by any other bacterial pathogen. Type VII secretion systems (T7SS) are used by both environmental and pathogenic mycobacteria to secrete proteins across their complex cell envelope. In the nonpathogenMycobacterium smegmatis, the ESX-1 T7SS plays a role in conjugation, and the ESX-3 T7SS is involved in metal homeostasis. InM. tuberculosis, these secretion systems have taken on roles in virulence, and they also are targets of the host immune response. ESX-3 secretes a heterodimer composed of EsxG (TB9.8) and EsxH (TB10.4), which impairs phagosome maturation in macrophages and is essential for virulence in mice. Given the importance of EsxG and EsxH during infection, we examined their regulation. WithM. tuberculosis, the secretion of EsxG and EsxH was regulated in response to iron and zinc, in accordance with the previously described transcriptional response of theesx-3locus to these metals. While iron regulated theesx-3expression in bothM. tuberculosisandM. smegmatis, there is a significant difference in the dynamics of this regulation. InM. smegmatis, theesx-3locus behaved like other iron-regulated genes such asmbtB. InM. tuberculosis, both iron and zinc modestly repressedesx-3expression. Diminished secretion of EsxG and EsxH in response to these metals altered the interaction ofM. tuberculosiswith macrophages, leading to impaired intracellularM. tuberculosissurvival. Our findings detail the regulatory differences ofesx-3inM. tuberculosisandM. smegmatisand demonstrate the importance of metal-dependent regulation of ESX-3 for virulence inM. tuberculosis.

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Mycosins Are Required for the Stabilization of the ESX-1 and ESX-5 Type VII Secretion Membrane Complexes

mBio ◽

10.1128/mbio.01471-16 ◽

2016 ◽

Vol 7 (5) ◽

Cited By ~ 29

Author(s):

Vincent J. C. van Winden ◽

Roy Ummels ◽

Sander R. Piersma ◽

Connie R. Jiménez ◽

Konstantin V. Korotkov ◽

...

Keyword(s):

Essential Role ◽

Intervention Strategies ◽

Independent Function ◽

Secretion Systems ◽

The Core ◽

Proper Functioning ◽

Type Vii Secretion ◽

Membrane Complex ◽

The Stability

ABSTRACT Pathogenic mycobacteria contain up to five type VII secretion (T7S) systems, ESX-1 to ESX-5. One of the conserved T7S components is the serine protease mycosin (MycP). Strikingly, whereas MycP is essential for secretion, the protease activity of MycP 1 in Mycobacterium tuberculosis has been shown to be dispensable for secretion. The essential role of MycP therefore remains unclear. Here we show that MycP 1 and MycP 5 of M. marinum have similar phenotypes, confirming that MycP has a second unknown function that is essential for its T7S system. To investigate whether this role is related to proper functioning of the T7S membrane complex, we first analyzed the composition of the ESX-1 membrane complex and showed that this complex consists of EccBCDE 1 , similarly to what was previously shown for ESX-5. Surprisingly, while mycosins are not an integral part of these purified core complexes, we noticed that the stability of both the ESX-1 complex and the ESX-5 complex is compromised in the absence of their MycP subunit. Additional interaction studies showed that, although mycosins are not part of the central ESX membrane complex, they loosely associate with this complex. We hypothesize that this MycP association with the core membrane complex is crucial for the integrity and functioning of the T7S machinery. IMPORTANCE Among the major virulence factors of pathogenic mycobacteria are the type VII secretion (T7S) systems. Three of these systems, ESX-1, ESX-3, and ESX-5, have been shown to be crucial for virulence or viability. Here we describe the function of mycosin proteases, which are conserved components within these systems. We show that MycP 1 and MycP 5 have a second, proteolytic-independent function which is essential for the T7S system. We additionally found that this second essential role is related to the stabilization and proper functioning of their respective ESX membrane core complexes. Finally, we found that this is mediated by a loose association of MycP with the complex. Understanding the essential role of mycosins in type VII secretion systems, which play central roles in the virulence and viability of pathogenic mycobacteria, may provide new intervention strategies to treat tuberculosis.

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Faculty Opinions recommendation of Pan-genome analysis highlights the extent of genomic variation in cultivated and wild rice.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.732499418.793559379 ◽

2019 ◽

Author(s):

Laura Privalle

Keyword(s):

Genome Analysis ◽

Wild Rice ◽

Genomic Variation ◽

Pan Genome

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Type VII secretion systems: structure, functions and transport models

Nature Reviews Microbiology ◽

10.1038/s41579-021-00560-5 ◽

2021 ◽

Author(s):

Angel Rivera-Calzada ◽

Nikolaos Famelis ◽

Oscar Llorca ◽

Sebastian Geibel

Keyword(s):

Structure Functions ◽

Secretion Systems ◽

Transport Models ◽

Type Vii Secretion

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Pan-Genome Analysis of Mycobacterium Africanum: Insights to Dynamics and Evolution.

10.21203/rs.3.rs-34142/v1 ◽

2020 ◽

Author(s):

Idowu Olawoye ◽

Simon D.W. Frost ◽

Christian T. Happi

Keyword(s):

West Africa ◽

Genome Analysis ◽

West African ◽

Multiple Copy ◽

Genome Sequences ◽

Animal Reservoir ◽

Pan Genome ◽

Lineage Specificity ◽

Mycobacterium Africanum ◽

Core Genes

Abstract Background: Mycobacterium tuberculosis complex (MTBC) consists of seven major lineages with three of them reported to circulate within West Africa: lineage 5 (West African 1) and lineage 6 (West African 2) which are geographically restricted to West Africa and lineage 4 (Euro-American lineage) which is found globally. It is unclear why the West African lineages are not found elsewhere; some hypotheses suggest that it could either be harboured by an animal reservoir which is restricted to West Africa, or strain preference for hosts of West African ethnicity, or inability to compete with other lineages in other locations.We tested the hypothesis that M. africanum West African 2 (lineage 6) might have emigrated out of West Africa but was outcompeted by more virulent modern strains of M. tuberculosis (MTB).Whole genome sequences of M. tuberculosis from Nigeria (n=21), South Africa (n=24) and M. africanum West African 2 from Mali (n=22) were retrieved, and a pan-genome analysis was performed after fully annotating these genomes. Results: The outcome of this analysis shows that Lineages 2, 4 and 6 all have a close pan-genome. We also see a correlation in numbers of some multiple copy core genes and amino acid substitution with lineage specificity that may have contributed to geographical distribution of these lineages.Conclusions: The findings in this study provides a perspective to one of the hypotheses that M. africanum West African 2 might find it difficult to compete against the more modern lineages outside West Africa hence its localization to the geographical region.

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