A Duplicated ESAT-6 Region of ESX-5 Is Involved in Protein Export and Virulence of Mycobacteria

ABSTRACTThe ESX-5 secretion system ofMycobacterium tuberculosisis important for bacterial virulence and for the secretion of the large PE/PPE protein family, whose genes constitute 10% of theM. tuberculosisgenome. A four-gene region of the ESX-5 system is duplicated three times in theM. tuberculosisgenome, but the functions of these duplicates are unknown. Here we investigated one of these duplicates: the region carrying theesxI,esxJ,ppe15, andpe8genes (ESX-5a). An ESX-5a deletion mutant in the model systemM. marinumbackground was deficient in the secretion of some members of the PE/PPE family of proteins. Surprisingly, we also identified other proteins that are not members of this family, thus expanding the range of ESX-5 secretion substrates. In addition, we demonstrated that ESX-5a is important for the virulence ofM. marinumin the zebrafish model. Furthermore, we showed the role of theM. tuberculosisESX-5a region in inflammasome activation but not host cell death induction, which is different from the case for theM. tuberculosisESX-5 system. In conclusion, the ESX-5a region is nonredundant with its ESX-5 paralog and is necessary for secretion of a specific subset of proteins inM. tuberculosisandM. marinumthat are important for bacterial virulence ofM. marinum. Our findings point to a role for the three ESX-5 duplicate regions in the selection of substrates for secretion via ESX-5, and hence, they provide the basis for a refined model of the molecular mechanism of this type VII secretion system.

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The Whole-Genome Sequence of Plasmid-Bearing Staphylococcus argenteus Strain B3-25B from Retail Beef Liver Encodes the Type VII Secretion System and Several Virulence Factors

Microbiology Resource Announcements ◽

10.1128/mra.00962-19 ◽

2019 ◽

Vol 8 (45) ◽

Cited By ~ 2

Author(s):

Leena Neyaz ◽

Anand B. Karki ◽

Mohamed K. Fakhr

Keyword(s):

Virulence Factors ◽

Genome Sequence ◽

Secretion System ◽

Whole Genome Sequence ◽

Whole Genome ◽

Circular Chromosome ◽

Beef Liver ◽

Content Type ◽

Type Vii Secretion ◽

Type Vii Secretion System

The whole-genome sequence of Staphylococcus argenteus strain B3-25B, isolated from retail beef liver, comprises a circular chromosome (2,676,222 bp) and a single plasmid (21,570 bp). The chromosome harbors genes encoding the type VII secretion system and several virulence factors.

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Genomics of Atlantic Forest Mycobacteriaceae strains unravels a mobilome diversity with a novel integrative conjugative element and plasmids harbouring T7SS

Microbial Genomics ◽

10.1099/mgen.0.000382 ◽

2020 ◽

Vol 6 (7) ◽

Author(s):

Sergio Mascarenhas Morgado ◽

Ana Carolina Paulo Vicente

Keyword(s):

Atlantic Forest ◽

Mobile Genetic Elements ◽

Content Type ◽

Genetic Elements ◽

Link Type ◽

Type Vii Secretion ◽

Integrative Conjugative Element ◽

Type Vii Secretion System ◽

Integrative Conjugative Elements

Mobile genetic elements (MGEs) are agents of bacterial evolution and adaptation. Genome sequencing provides an unbiased approach that has revealed an abundance of MGEs in prokaryotes, mainly plasmids and integrative conjugative elements. Nevertheless, many mobilomes, particularly those from environmental bacteria, remain underexplored despite their representing a reservoir of genes that can later emerge in the clinic. Here, we explored the mobilome of the Mycobacteriaceae family, focusing on strains from Brazilian Atlantic Forest soil. Novel Mycolicibacterium and Mycobacteroides strains were identified, with the former ones harbouring linear and circular plasmids encoding the specialized type-VII secretion system (T7SS) and mobility-associated genes. In addition, we also identified a T4SS-mediated integrative conjugative element (ICEMyc226) encoding two T7SSs and a number of xenobiotic degrading genes. Our study uncovers the diversity of the Mycobacteriaceae mobilome, providing the evidence of an ICE in this bacterial family. Moreover, the presence of T7SS genes in an ICE, as well as plasmids, highlights the role of these mobile genetic elements in the dispersion of T7SS.

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CFP-10 from Mycobacterium tuberculosis Selectively Activates Human Neutrophils through a Pertussis Toxin-Sensitive Chemotactic Receptor

Infection and Immunity ◽

10.1128/iai.02493-14 ◽

2014 ◽

Vol 83 (1) ◽

pp. 205-213 ◽

Cited By ~ 18

Author(s):

Amanda Welin ◽

Halla Björnsdottir ◽

Malene Winther ◽

Karin Christenson ◽

Tudor Oprea ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Pertussis Toxin ◽

Human Neutrophils ◽

Content Type ◽

Chaperone Function ◽

Type Vii Secretion ◽

Chaperone Protein ◽

Type Vii Secretion System ◽

G Protein Coupled

Upon infection withMycobacterium tuberculosis, neutrophils are massively recruited to the lungs, but the role of these cells in combating the infection is poorly understood. Through a type VII secretion system,M. tuberculosisreleases a heterodimeric protein complex, containing a 6-kDa early secreted antigenic target (ESAT-6) and a 10-kDa culture filtrate protein (CFP-10), that is essential for virulence. Whereas the ESAT-6 component possesses multiple virulence-related activities, no direct biological activity of CFP-10 has been shown, and CFP-10 has been described as a chaperone protein for ESAT-6. We here show that the ESAT-6:CFP-10 complex induces a transient release of Ca2+from intracellular stores in human neutrophils. Surprisingly, CFP-10 rather than ESAT-6 was responsible for triggering the Ca2+response, in a pertussis toxin-sensitive manner, suggesting the involvement of a G-protein-coupled receptor. In line with this, the response was accompanied by neutrophil chemotaxis and activation of the superoxide-producing NADPH-oxidase. Neutrophils were unique among leukocytes in responding to CFP-10, as monocytes and lymphocytes failed to produce a Ca2+signal upon stimulation with theM. tuberculosisprotein. Hence, CFP-10 may contribute specifically to neutrophil recruitment and activation duringM. tuberculosisinfection, representing a novel biological role for CFP-10 in the ESAT-6:CFP-10 complex, beyond the previously described chaperone function.

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ESX-1-Independent Horizontal Gene Transfer by Mycobacterium tuberculosis Complex Strains

mBio ◽

10.1128/mbio.00965-21 ◽

2021 ◽

Vol 12 (3) ◽

Author(s):

Jan Madacki ◽

Mickael Orgeur ◽

Guillem Mas Fiol ◽

Wafa Frigui ◽

Laurence Ma ◽

...

Keyword(s):

Mycobacterium Tuberculosis ◽

Mycobacterium Smegmatis ◽

Secretion System ◽

Dna Transfer ◽

Chromosomal Dna ◽

Content Type ◽

Type Vii Secretion ◽

Wide Range ◽

Population Structures ◽

Type Vii Secretion System

ABSTRACT Current models of horizontal gene transfer (HGT) in mycobacteria are based on “distributive conjugal transfer” (DCT), an HGT type described in the fast-growing, saprophytic model organism Mycobacterium smegmatis, which creates genome mosaicism in resulting strains and depends on an ESX-1 type VII secretion system. In contrast, only few data on interstrain DNA transfer are available for tuberculosis-causing mycobacteria, for which chromosomal DNA transfer between two Mycobacterium canettii strains was reported, a process which, however, was not observed for Mycobacterium tuberculosis strains. Here, we have studied a wide range of human- and animal-adapted members of the Mycobacterium tuberculosis complex (MTBC) using an optimized filter-based mating assay together with three selected strains of M. canettii that acted as DNA recipients. Unlike in previous approaches, we obtained a high yield of thousands of recombinants containing transferred chromosomal DNA fragments from various MTBC donor strains, as confirmed by whole-genome sequence analysis of 38 randomly selected clones. While the genome organizations of the obtained recombinants showed mosaicisms of donor DNA fragments randomly integrated into a recipient genome backbone, reminiscent of those described as being the result of ESX-1-mediated DCT in M. smegmatis, we observed similar transfer efficiencies when ESX-1-deficient donor and/or recipient mutants were used, arguing that in tubercle bacilli, HGT is an ESX-1-independent process. These findings provide new insights into the genetic events driving the pathoevolution of M. tuberculosis and radically change our perception of HGT in mycobacteria, particularly for those species that show recombinogenic population structures despite the natural absence of ESX-1 secretion systems. IMPORTANCE Data on the bacterial sex-mediated impact on mycobacterial evolution are limited. Hence, our results presented here are of importance as they clearly demonstrate the capacity of a wide range of human- and animal-adapted Mycobacterium tuberculosis complex (MTBC) strains to transfer chromosomal DNA to selected strains of Mycobacterium canettii. Most interestingly, we found that interstrain DNA transfer among tubercle bacilli was not dependent on a functional ESX-1 type VII secretion system, as ESX-1 deletion mutants of potential donor and/or recipient strains yielded numbers of recombinants similar to those of their respective parental strains. These results argue that HGT in tubercle bacilli is organized in a way different from that of the most widely studied Mycobacterium smegmatis model, a finding that is also relevant beyond tubercle bacilli, given that many mycobacteria, like, for example, Mycobacterium avium or Mycobacterium abscessus, are naturally devoid of an ESX-1 secretion system but show recombinogenic, mosaic-like genomic population structures.

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Streptococcus suis serotype 9 strain GZ0565 contains a type VII secretion system putative substrate EsxA that contributes to bacterial virulence and a vanZ- like gene that confers resistance to teicoplanin and dalbavancin in Streptococcus agalactiae

Veterinary Microbiology ◽

10.1016/j.vetmic.2017.04.030 ◽

2017 ◽

Vol 205 ◽

pp. 26-33 ◽

Cited By ~ 13

Author(s):

Liying Lai ◽

Jiao Dai ◽

Huanyu Tang ◽

Shouming Zhang ◽

Chunyan Wu ◽

...

Keyword(s):

Streptococcus Agalactiae ◽

Streptococcus Suis ◽

Secretion System ◽

Bacterial Virulence ◽

Type Vii Secretion ◽

Type Vii Secretion System ◽

Suis Serotype

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Genetic functions of the NAIP family of inflammasome receptors for bacterial ligands in mice

Journal of Experimental Medicine ◽

10.1084/jem.20160006 ◽

2016 ◽

Vol 213 (5) ◽

pp. 647-656 ◽

Cited By ~ 42

Author(s):

Yue Zhao ◽

Jianjin Shi ◽

Xuyan Shi ◽

Yupeng Wang ◽

Fengchao Wang ◽

...

Keyword(s):

Legionella Pneumophila ◽

Type Iii Secretion ◽

Physiological Function ◽

Shigella Flexneri ◽

Critical Role ◽

Bacterial Virulence ◽

Infection Model ◽

Inflammasome Activation ◽

Inflammatory Damage

Biochemical studies suggest that the NAIP family of NLR proteins are cytosolic innate receptors that directly recognize bacterial ligands and trigger NLRC4 inflammasome activation. In this study, we generated Naip5−/−, Naip1−/−, and Naip2−/− mice and showed that bone marrow macrophages derived from these knockout mice are specifically deficient in detecting bacterial flagellin, the type III secretion system needle, and the rod protein, respectively. Naip1−/−, Naip2−/−, and Naip5−/− mice also resist lethal inflammasome activation by the corresponding ligand. Furthermore, infections performed in the Naip-deficient macrophages have helped to define the major signal in Legionella pneumophila, Salmonella Typhimurium and Shigella flexneri that is detected by the NAIP/NLRC4 inflammasome. Using an engineered S. Typhimurium infection model, we demonstrate the critical role of NAIPs in clearing bacterial infection and protecting mice from bacterial virulence–induced lethality. These results provide definitive genetic evidence for the important physiological function of NAIPs in antibacterial defense and inflammatory damage–induced lethality in mice.

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Structure of EspB from the ESX-1 Type VII Secretion System and Insights into its Export Mechanism

Structure ◽

10.1016/j.str.2015.01.002 ◽

2015 ◽

Vol 23 (3) ◽

pp. 571-583 ◽

Cited By ~ 42

Author(s):

Matthew Solomonson ◽

Dheva Setiaputra ◽

Karl A.T. Makepeace ◽

Emilie Lameignere ◽

Evgeniy V. Petrotchenko ◽

...

Keyword(s):

Secretion System ◽

Type Vii Secretion ◽

Type Vii Secretion System

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Infect and Inject: How Mycobacterium tuberculosis Exploits Its Major Virulence-Associated Type VII Secretion System, ESX-1

Bacteria and Intracellularity ◽

10.1128/microbiolspec.bai-0024-2019 ◽

2019 ◽

pp. 113-126 ◽

Cited By ~ 4

Author(s):

Sangeeta Tiwari ◽

Rosalyn Casey ◽

Celia W. Goulding ◽

Suzie Hingley-Wilson ◽

William R. Jacobs

Keyword(s):

Mycobacterium Tuberculosis ◽

Secretion System ◽

Type Vii Secretion ◽

Type Vii Secretion System

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OpiA, a Type Six Secretion System Substrate, Localizes to the Cell Pole and Plays a Role in Bacterial Growth and Viability in Francisella tularensis LVS

Journal of Bacteriology ◽

10.1128/jb.00048-20 ◽

2020 ◽

Vol 202 (14) ◽

Cited By ~ 1

Author(s):

Stuart Cantlay ◽

Kristen Haggerty ◽

Joseph Horzempa

Keyword(s):

Cell Size ◽

Francisella Tularensis ◽

Secretion System ◽

Live Vaccine ◽

Intracellular Pathogen ◽

Content Type ◽

Erythrocyte Invasion ◽

Host Pathogen

ABSTRACT Francisella tularensis is an intracellular pathogen and the causative agent of tularemia. The F. tularensis type six secretion system (T6SS) is required for a number of host-pathogen interactions, including phagolysosomal escape and invasion of erythrocytes. One known effector of the T6SS, OpiA, has recently been shown to be a phosphatidylinositol-3 kinase. To investigate the role of OpiA in erythrocyte invasion, we constructed an opiA-null mutant in the live vaccine strain, F. tularensis LVS. OpiA was not required for erythrocyte invasion; however, deletion of opiA affected growth of F. tularensis LVS in broth cultures in a medium-dependent manner. We also found that opiA influenced cell size, gentamicin sensitivity, bacterial viability, and the lipid content of F. tularensis. A fluorescently tagged OpiA (OpiA–emerald-green fluorescent protein [EmGFP]) accumulated at the cell poles of F. tularensis, which is consistent with the location of the T6SS. However, OpiA-EmGFP also exhibited a highly dynamic localization, and this fusion protein was detected in erythrocytes and THP-1 cells in vitro, further supporting that OpiA is secreted. Similar to previous reports with F. novicida, our data demonstrated that opiA had a minimal effect on intracellular replication of F. tularensis in host immune cells in vitro. However, THP-1 cells infected with the opiA mutant produced modestly (but significantly) higher levels of the proinflammatory cytokine tumor necrosis factor alpha compared to these host cells infected with wild-type bacteria. We conclude that, in addition to its role in host-pathogen interactions, our results reveal that the function of opiA is central to the biology of F. tularensis bacteria. IMPORTANCE F. tularensis is a pathogenic intracellular pathogen that is of importance for public health and strategic defense. This study characterizes the opiA gene of F. tularensis LVS, an attenuated strain that has been used as a live vaccine but that also shares significant genetic similarity to related Francisella strains that cause human disease. The data presented here provide the first evidence of a T6SS effector protein that affects the physiology of F. tularensis, namely, the growth, cell size, viability, and aminoglycoside resistance of F. tularensis LVS. This study also adds insight into our understanding of OpiA as a determinant of virulence. Finally, the fluorescence fusion constructs presented here will be useful tools for dissecting the role of OpiA in infection.

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