scholarly journals A membrane-depolarizing toxin substrate of the Staphylococcus aureus Type VII secretion system mediates intra-species competition

2018 ◽  
Author(s):  
Fatima R. Ulhuq ◽  
Margarida C. Gomes ◽  
Gina Duggan ◽  
Manman Guo ◽  
Chriselle Mendonca ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pathogenic Bacteria ◽  
Secretion System ◽  
Mucosal Barrier ◽  
Infection Model ◽  
Species Competition ◽  
Type Vii Secretion ◽  
Proteomic Approach ◽  
Type Vii Secretion System

AbstractThe type VII protein secretion system (T7SS) is conserved across Staphylococcus aureus strains and plays important roles in virulence and interbacterial competition. To date only one T7SS substrate protein, encoded in a subset of S. aureus genomes, has been functionally characterized. Here, using an unbiased proteomic approach, we identify TspA as a further T7SS substrate. TspA is encoded distantly from the T7SS gene cluster and is found across all S. aureus strains as well as in Listeria and Enterococci. Heterologous expression of TspA from S. aureus strain RN6390 indicates its C-terminal domain is toxic when targeted to the Escherichia coli periplasm and that it depolarizes the cytoplasmic membrane. The membrane depolarizing activity is alleviated by co-production of the membrane-bound TsaI immunity protein, which is encoded adjacent to tspA on the S. aureus chromosome. Using a zebrafish hindbrain ventricle infection model, we demonstrate that the T7SS of strain RN6390 promotes bacterial replication in vivo, and deletion of tspA leads to increased bacterial clearance. The toxin domain of TspA is highly polymorphic and S. aureus strains encode multiple tsaI homologues at the tspA locus, suggestive of additional roles in intra-species competition. In agreement, we demonstrate TspA-dependent growth inhibition of RN6390 by strain COL in the zebrafish infection model that is alleviated by the presence of TsaI homologues.Significance statementStaphylococcus aureus, a human commensal organism that asymptomatically colonizes the nares, is capable of causing serious disease following breach of the mucosal barrier. S. aureus strains encode a Type VII secretion system (T7SS) that is required for virulence in mouse infection models, and some strains also secrete a nuclease toxin by this route that has antibacterial activity. Here we identify TspA, widely found in Staphylococci and other pathogenic bacteria, as a T7 substrate. We show that TspA has membrane-depolarizing activity and that S. aureus uses TspA to inhibit the growth of a bacterial competitor in vivo.

scholarly journals The Ess/Type VII secretion system of Staphylococcus aureus shows unexpected genetic diversity

BMC Genomics ◽  
2016 ◽  
Vol 17 (1) ◽  
Author(s):  
Ben Warne ◽  
Catriona P. Harkins ◽  
Simon R. Harris ◽  
Alexandra Vatsiou ◽  
Nicola Stanley-Wall ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Staphylococcus Aureus ◽  
Secretion System ◽  
Type Vii Secretion ◽  
Type Vii Secretion System

scholarly journals A membrane-depolarizing toxin substrate of theStaphylococcus aureustype VII secretion system mediates intraspecies competition

2020 ◽  
Vol 117 (34) ◽  
pp. 20836-20847 ◽  
Author(s):  
Fatima R. Ulhuq ◽  
Margarida C. Gomes ◽  
Gina M. Duggan ◽  
Manman Guo ◽  
Chriselle Mendonca ◽  
...  
Keyword(s):  
Secretion System ◽  
Infection Model ◽  
Substrate Protein ◽  
Proteomic Approach ◽  
Protein Secretion System ◽  
Membrane Bound ◽  
Intraspecies Competition ◽  
Dependent Growth ◽  
Bacterial Replication

The type VII protein secretion system (T7SS) is conserved acrossStaphylococcus aureusstrains and plays important roles in virulence and interbacterial competition. To date, only one T7SS substrate protein, encoded in a subset ofS. aureusgenomes, has been functionally characterized. Here, using an unbiased proteomic approach, we identify TspA as a further T7SS substrate. TspA is encoded distantly from the T7SS gene cluster and is found across allS. aureusstrains as well as inListeriaand Enterococci. Heterologous expression of TspA fromS. aureusstrain RN6390 indicates its C-terminal domain is toxic when targeted to theEscherichia coliperiplasm and that it depolarizes the cytoplasmic membrane. The membrane-depolarizing activity is alleviated by coproduction of the membrane-bound TsaI immunity protein, which is encoded adjacent totspAon theS. aureuschromosome. Using a zebrafish hindbrain ventricle infection model, we demonstrate that the T7SS of strain RN6390 promotes bacterial replication in vivo, and deletion oftspAleads to increased bacterial clearance. The toxin domain of TspA is highly polymorphic andS. aureusstrains encode multipletsaIhomologs at thetspAlocus, suggestive of additional roles in intraspecies competition. In agreement, we demonstrate TspA-dependent growth inhibition of RN6390 by strain COL in the zebrafish infection model that is alleviated by the presence of TsaI homologs.

scholarly journals Flotillin scaffold activity contributes to type VII secretion system assembly in Staphylococcus aureus

2017 ◽  
Vol 13 (11) ◽  
pp. e1006728 ◽  
Author(s):  
Benjamin Mielich-Süss ◽  
Rabea M. Wagner ◽  
Nicole Mietrach ◽  
Tobias Hertlein ◽  
Gabriella Marincola ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Secretion System ◽  
Type Vii Secretion ◽  
Type Vii Secretion System

scholarly journals Heme-iron plays a key role in the regulation of the Ess/Type VII secretion system ofStaphylococcus aureusRN6390

2017 ◽  
Author(s):  
M. Guillermina Casabona ◽  
Holger Kneuper ◽  
Daniela Alferes de Lima ◽  
Catriona P. Harkins ◽  
Martin Zoltner ◽  
...  
Keyword(s):  
Iron Homeostasis ◽  
Iron Acquisition ◽  
Secretion System ◽  
Heme Iron ◽  
Species Competition ◽  
Transcript Analysis ◽  
Type Vii Secretion ◽  
Protein Secretion System ◽  
Type Vii Secretion System ◽  
Translational Level

ABSTRACTTheStaphylococcus aureusType VII protein secretion system (T7SS) plays important roles in virulence and intra-species competition. Here we show that the T7SS in strain RN6390 is activated by supplementing the growth medium with hemoglobin, and its cofactor hemin (heme B). Transcript analysis and secretion assays suggest that activation by hemin occurs at a transcriptional and a post-translational level. Loss of T7 secretion activity by deletion ofessCresults in upregulation of genes required for iron acquisition. Taken together these findings suggest that the T7SS plays a role in iron homeostasis in at least someS. aureusstrains.

scholarly journals The type VII secretion system protects Staphylococcus aureus against antimicrobial host fatty acids

2019 ◽  
Author(s):  
Arnaud Kengmo Tchoupa ◽  
Kate E. Watkins ◽  
Rebekah A. Jones ◽  
Agnès Kuroki ◽  
Mohammad Tauqeer Alam ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Staphylococcus Aureus ◽  
Cell Membrane ◽  
Mutant Cell ◽  
Membrane Damage ◽  
Membrane Integrity ◽  
Secretion System ◽  
Membrane Phospholipids ◽  
Type Vii Secretion ◽  
Type Vii Secretion System

SummaryThe Staphylococcus aureus type VII secretion system (T7SS) exports several proteins that are pivotal for bacterial virulence. The mechanisms underlying T7SS-mediated staphylococcal survival during infection nevertheless remain unclear. Here we show that the absence of EsxC, a small secreted effector implicated in bacterial persistence, results in cell membrane defects in S. aureus. Interestingly, isogenic mutants lacking EsxC, other T7SS effectors EsxA and EsxB, or the membrane-bound ATPase EssC, are more sensitive to killing by the host-derived antimicrobial fatty acid, linoleic acid (LA), compared to the wild-type (WT). LA induces more cell membrane damage in the T7SS mutants compared to the WT. Although WT and mutant strains did not differ in their ability to bind labelled LA, membrane lipid profiles show that T7SS mutants are less able to incorporate LA into their membrane phospholipids. Furthermore, proteomic analyses of WT and mutant cell fractions reveal that, in addition to compromising membranes, T7SS defects induce oxidative stress and hamper their response to LA challenge. Thus, our findings indicate that T7SS is crucial for S. aureus membrane integrity and homeostasis, which is critical when bacteria encounter antimicrobial fatty acids.

scholarly journals EsaB is a core component of the Staphylococcus aureus Type VII secretion system

2017 ◽  
Author(s):  
M. Guillermina Casabona ◽  
Grant Buchanan ◽  
Martin Zoltner ◽  
Catriona P. Harkins ◽  
Matthew T.G. Holden ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Fluorescent Protein ◽  
Iron Acquisition ◽  
Yellow Fluorescent Protein ◽  
Secretion System ◽  
Secretion Systems ◽  
Core Component ◽  
Type Vii Secretion ◽  
Bacterial Competition ◽  
Type Vii Secretion System

AbstractType VII secretion systems (T7SS) are found in many bacteria and secrete proteins involved in virulence and bacterial competition. In Staphylococcus aureus the small ubiquitin-like EsaB protein has been previously implicated as having a regulatory role in the production of the EsxC substrate. Here we show that in the S. aureus RN6390 strain, EsaB does not genetically regulate production of any T7 substrates or components, but is indispensable for secretion activity. Consistent with EsaB being a core component of the T7SS, loss of either EsaB or EssC are associated with upregulation of a common set of iron acquisition genes. However, a further subset of genes were dysregulated only in the absence of EsaB. In addition, fractionation revealed that although an EsaB fusion to yellow fluorescent protein partially localised to the membrane, it was still membrane-localised when the T7SS was absent. Taken together our findings suggest that EsaB has T7SS-dependent and T7SS-independent roles in S. aureus.

scholarly journals The type VII secretion system of Staphylococcus aureus secretes a nuclease toxin that targets competitor bacteria

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhenping Cao ◽  
M. Guillermina Casabona ◽  
Holger Kneuper ◽  
James D. Chalmers ◽  
Tracy Palmer
Keyword(s):  
Staphylococcus Aureus ◽  
Secretion System ◽  
Type Vii Secretion ◽  
Type Vii Secretion System

scholarly journals Functional analysis of the EsaB component of the Staphylococcus aureus Type VII secretion system

Microbiology ◽  
2017 ◽  
Vol 163 (12) ◽  
pp. 1851-1863 ◽  
Author(s):  
M. Guillermina Casabona ◽  
Grant Buchanan ◽  
Martin Zoltner ◽  
Catriona P. Harkins ◽  
Matthew T. G. Holden ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Functional Analysis ◽  
Secretion System ◽  
Type Vii Secretion ◽  
Type Vii Secretion System

scholarly journals Characterization of Staphylococcus aureus EssB, an integral membrane component of the Type VII secretion system: atomic resolution crystal structure of the cytoplasmic segment

2012 ◽  
Vol 449 (2) ◽  
pp. 469-477 ◽  
Author(s):  
Martin Zoltner ◽  
Paul K. Fyfe ◽  
Tracy Palmer ◽  
William N. Hunter
Keyword(s):  
Staphylococcus Aureus ◽  
Protein Interactions ◽  
Protein Translocation ◽  
Secretion System ◽  
Full Length ◽  
Protein Protein Interactions ◽  
Gram Positive Bacteria ◽  
Type Vii Secretion ◽  
Early Secretory Antigenic Target ◽  
Type Vii Secretion System

The Type VII protein translocation/secretion system, unique to Gram-positive bacteria, is a key virulence determinant in Staphylococcus aureus. We aim to characterize the architecture of this secretion machinery and now describe the present study of S. aureus EssB, a 52 kDa bitopic membrane protein essential for secretion of the ESAT-6 (early secretory antigenic target of 6 kDa) family of proteins, the prototypic substrate of Type VII secretion. Full-length EssB was heterologously expressed in Escherichia coli, solubilized from the bacterial membrane, purified to homogeneity and shown to be dimeric. A C-terminal truncation, EssB∆C, and two soluble fragments termed EssB-N and EssB-C, predicted to occur on either side of the cytoplasmic membrane, have been successfully purified in a recombinant form, characterized and, together with the full-length protein, used in crystallization trials. EssB-N, the 25 kDa N-terminal cytoplasmic fragment, gave well-ordered crystals and we report the structure, determined by SAD (single-wavelength anomalous diffraction) targeting an SeMet (selenomethionine) derivative, refined to atomic (1.05 Å; 1 Å=0.1 nm) resolution. EssB-N is dimeric in solution, but crystallizes as a monomer and displays a fold comprised of two globular domains separated by a cleft. The structure is related to that of serine/threonine protein kinases and the present study identifies that the Type VII secretion system exploits and re-uses a stable modular entity and fold that has evolved to participate in protein–protein interactions in a similar fashion to the catalytically inert pseudokinases.

scholarly journals In Vitro and In Vivo Activities of Tigecycline (GAR-936), Daptomycin, and Comparative Antimicrobial Agents against Glycopeptide-Intermediate Staphylococcus aureus and Other Resistant Gram-Positive Pathogens

2002 ◽  
Vol 46 (8) ◽  
pp. 2595-2601 ◽  
Author(s):  
Peter J. Petersen ◽  
Patricia A. Bradford ◽  
William J. Weiss ◽  
Timothy M. Murphy ◽  
P. E. Sum ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Pathogenic Bacteria ◽  
Antimicrobial Agents ◽  
Clinical Laboratory ◽  
Infection Model ◽  
National Committee ◽  
Gram Positive ◽  
Mueller Hinton ◽  
Mueller Hinton Broth

ABSTRACT Tigecycline (GAR-936) and daptomycin are potent antibacterial compounds in advanced stages of clinical trials. These novel agents target multiply resistant pathogenic bacteria. Daptomycin is principally active against gram-positive bacteria, while tigecycline has broad-spectrum activity. When tested by the standard protocols of the National Committee for Clinical Laboratory Standards in Mueller-Hinton broth II, tigecycline was more active than daptomycin (MICs at which 90% of isolates tested are inhibited, 0.12 to 1 and 0.5 to 16 μg/ml, respectively) against staphylococcal, enterococcal, and streptococcal pathogens. Daptomycin demonstrated a stepwise increase in activity corresponding to an increase in the supplemental concentration of calcium. When tested in base Mueller-Hinton broth supplemented with 50 mg of calcium per liter, daptomycin demonstrated improved activity (MIC90s, 0.015 to 4 μg/ml). The activity of daptomycin, however, equaled that of tigecycline against the glycopeptide-intermediate Staphylococcus aureus (GISA) strains only when the test medium was supplemented with excess calcium (75 mg/liter). Tigecycline and daptomycin demonstrated in vivo efficacies against GISA, methicillin-resistant S. aureus, and methicillin-susceptible S. aureus strains in an intraperitoneal systemic murine infection model. These data suggest that tigecycline and daptomycin may offer therapeutic options against clinically relevant resistant pathogens for which current alternatives for treatment are limited.

Sign in / Sign up

Export Citation Format

Share Document