The TIR Homologue Lies near Resistance Genes in Staphylococcus aureus, Coupling Modulation of Virulence and Antimicrobial Susceptibility

Patot, Sabine; Imbert, Paul R. C.; Baude, Jessica; Simões, Patrícia Martins; Campergue, Jean-Baptiste; Louche, Arthur; Nijland, Reindert; Bes, Michèle; Tristan, Anne; Laurent, François; Fischer, Adrien; Schrenzel, Jacques; Vandenesch, François; Salcedo, Suzana P.; François, Patrice; Lina, Gérard

doi:10.1371/journal.ppat.1006092

Cited by 34 publications

(31 citation statements)

References 53 publications

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“…Expression of the TIR domain alone (BtpB-TIR) resulted in the formation of long filament-like structures that showed no colocalization with tubulin ( Fig 6), consistent with the results obtained in the yeast model. In some cells, BtpB-TIR induced disorganization of the microtubule network ( what has been previously described for the Staphyloccocus aureus TirS protein [7]. Most likely, as also inferred from the above yeast data, these structures correspond to self-assembled ordered filaments consisting of the TIR domain, which are absent when stabilized by the presence of the N-terminal domain.…”

Section: Inhibition Of Endocytosis Occurs Upon Ectopic Expression Ofsupporting

confidence: 71%

“…TcpC inhibition of TRIF-and IL-6/IL-1-dependent pathways has also been described [6]. Interestingly, the observation that expression of TirS from Staphylococcus aureus, present in a multi-drug resistant (MDR) island of numerous clinical isolates, is induced by specific antibiotic treatment [7] raises the possibility that these bacterial proteins may be tightly regulated, enhancing virulence, persistence or dissemination in particular clinical contexts such as exposure to selective pressure.…”

Section: Introductionmentioning

confidence: 92%

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The TIR-domain containing effectors BtpA and BtpB from Brucella abortus impact NAD metabolism

et al. 2020

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Brucella species are facultative intracellular Gram-negative bacteria relevant to animal and human health. Their ability to establish an intracellular niche and subvert host cell pathways to their advantage depends on the delivery of bacterial effector proteins through a type IV secretion system. Brucella Toll/Interleukin-1 Receptor (TIR)-domain-containing proteins BtpA (also known as TcpB) and BtpB are among such effectors. Although divergent in primary sequence, they interfere with Toll-like receptor (TLR) signaling to inhibit the innate immune responses. However, the molecular mechanisms implicated still remain unclear. To gain insight into the functions of BtpA and BtpB, we expressed them in the budding yeast Saccharomyces cerevisiae as a eukaryotic cell model. We found that both effectors were cytotoxic and that their respective TIR domains were necessary and sufficient for yeast growth inhibition. Growth arrest was concomitant with actin depolymerization, endocytic block and a general decrease in kinase activity in the cell, suggesting a failure in energetic metabolism. Indeed, levels of ATP and NAD + were low in yeast cells expressing BtpA and BtpB TIR domains, consistent with the recently described enzymatic activity of some TIR domains as NAD + hydrolases. In human epithelial cells, both BtpA and BtpB expression reduced intracellular total NAD levels. In infected cells, both BtpA and BtpB contributed to reduction of total NAD, indicating that their NAD + hydrolase functions are active intracellularly during infection. Overall, combining the yeast model together with mammalian cells and infection studies our results show that BtpA and BtpB modulate energy metabolism in host cells through NAD + hydrolysis, assigning a novel role for these TIR domain-containing effectors in Brucella pathogenesis.

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Section: Inhibition Of Endocytosis Occurs Upon Ectopic Expression Ofsupporting

confidence: 71%

Section: Introductionmentioning

confidence: 92%

The TIR-domain containing effectors BtpA and BtpB from Brucella abortus impact NAD metabolism

et al. 2020

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“…In some cells, BtpB-TIR induced disorganization of the microtubule network (S5C Fig). These filamentous structures did not co-localize with vimentin either, a marker of intermediate filaments (S5D Fig), strongly reminiscent of what has been previously described for the Staphyloccocus aureus TirS protein [7]. Most likely, as also inferred from the above yeast data, these structures correspond to self-assembled ordered filaments consisting of the TIR domain, which are absent when stabilized by the presence of the N-terminal domain.…”

Section: Resultssupporting

confidence: 79%

The TIR-domain containing effectors BtpA and BtpB fromBrucella abortusblock energy metabolism

Coronas-Serna

Louche

Rodríguez-Escudero

et al. 2019

Preprint

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27Brucella species are facultative intracellular Gram-negative bacteria relevant to animal 28 and human health. Their ability to establish an intracellular niche and subvert host cell 29 pathways to their advantage depends on the delivery of bacterial effector proteins 30 through a type IV secretion system. Brucella Toll/Interleukin-1 Receptor (TIR)-domain-31 containing proteins BtpA (also known as TcpB) and BtpB are among such effectors. 32Although divergent in primary sequence, they interfere with Toll-like receptor (TLR) 33 signaling to inhibit the innate immune responses. However, the molecular mechanisms 34 implicated still remain unclear. To gain insight into the functions of BtpA and BtpB, we 35 expressed them in the budding yeast Saccharomyces cerevisiae as a eukaryotic cell 36 model. We found that both effectors were cytotoxic and that their respective TIR 37 domains were necessary and sufficient for yeast growth inhibition. Growth arrest was 38 concomitant with actin depolymerization, endocytic block and a general decrease in 39 kinase activity in the cell, suggesting a failure in energetic metabolism. Indeed, levels of 40 ATP and NAD + were low in yeast cells expressing BtpA and BtpB TIR domains, 41 consistent with the recently described enzymatic activity of some TIR domains as 42 NAD + hydrolases. In human epithelial cells, both BtpA and BtpB expression reduced 43 intracellular total NAD levels. In infected cells, both BtpA and BtpB contributed to 44 reduction of total NAD, indicating that their NAD + hydrolase functions are active 45 intracellularly during infection. Overall, combining the yeast model together with 46 mammalian cells and infection studies our results show that BtpA and BtpB modulate 47 AUTHOR SUMMARY 51Brucella is a genus of zoonotic bacteria that cause severe disease in a variety of 52 mammals, ranging from farm animals (as bovines, swine and ovine) to marine 53 mammals. Transmission to humans, often by ingestion of non-treated dairy products, 54 leads to serious systemic infection. Brucella abortus invades host cells and replicates 55intracellularly. Such behavior relies on the injection of bacterial proteins into the host 56 cytoplasm via specialized secretion systems. Our work focuses on the study of two of 57 these factors, BtpA and BtpB, previously described to contain Toll/Interleukin-1 58Receptor (TIR)-domains that modulate innate immunity. We use here two biological 59 models: the yeast Saccharomyces cerevisiae and human cell lines. We found that the 60 TIR domains of both Brucella proteins were necessary and sufficient to collapse energy 61 metabolism in yeast by depleting ATP and NAD + . This result was translatable to higher 62 cells and consistent with the recently described NADase activity of some TIR domains 63 both in mammalian and bacterial proteins. Importantly, we demonstrate that Brucella 64 down-regulates total NAD levels in host cells by using both BtpA and BtpB effectors. 65Our results show that NAD + is targeted by Brucella during infection, which may 66 cons...

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“…First, prior work from our laboratory in a mouse model of S. aureus catheterassociated biofilm infection also demonstrated a TLR9independent phenotype [22], confirming the findings obtained during craniotomy infection. Second, as previously mentioned, numerous S. aureus virulence determinants have recently been identified that interfere with TLR2 recognition or signaling [46][47][48][49]; however, to date, no S. aureus inhibitors of TLR9-dependent pathways have been reported. By extension, this suggests that TLR2-mediated recognition of S. aureus is more relevant for bacterial clearance, since this pathway has been extensively targeted by the organism.…”

Section: Discussionmentioning

confidence: 99%

“…IL-1β is critical for S. aureus containment during craniotomy infection, but is not sufficient for bacterial clearance, since biofilm infections persist in an immune competent host during craniotomy infection. Prior studies have identified several molecules that are produced by planktonic S. aureus that interfere with TLR2-dependent recognition, including lipase (Geh) [46], staphylococcal superantigenlike protein 3 (SSL3) [47], and molecular mimicry via blocking the Toll-interacting receptor (Tir) domain of TLR2 [48,49]. In addition, the paired-immunoglobulinlike receptor (PIR)-B contains an inhibitory immunoreceptor tyrosine-based inhibition (ITIM) motif that upon binding S. aureus lipoteichoic acid, dampens proinflammatory cytokine production [50,51].…”

Section: Discussionmentioning

confidence: 99%

TLR2 and caspase-1 signaling are critical for bacterial containment but not clearance during craniotomy-associated biofilm infection

Aldrich

Heim

Shi

et al. 2020

J Neuroinflammation

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Background: A craniotomy is required to access the brain for tumor resection or epilepsy treatment, and despite precautionary measures, infectious complications occur at a frequency of 1-3%. Approximately half of craniotomy infections are caused by Staphylococcus aureus (S. aureus) that forms a biofilm on the bone flap, which is recalcitrant to antibiotics. Our prior work in a mouse model of S. aureus craniotomy infection revealed a critical role for myeloid differentiation factor 88 (MyD88) in bacterial containment and pro-inflammatory mediator production. Since numerous receptors utilize MyD88 as a signaling adaptor, the current study examined the importance of Tolllike receptor 2 (TLR2) and TLR9 based on their ability sense S. aureus ligands, namely lipoproteins and CpG DNA motifs, respectively. We also examined the role of caspase-1 based on its known association with TLR signaling to promote IL-1β release. Methods: A mouse model of craniotomy-associated biofilm infection was used to investigate the role of TLR2, TLR9, and caspase-1 in disease progression. Wild type (WT), TLR2 knockout (KO), TLR9 KO, and caspase-1 KO mice were examined at various intervals post-infection to quantify bacterial burden, leukocyte recruitment, and inflammatory mediator production in the galea, brain, and bone flap. In addition, the role of TLR2-dependent signaling during microglial/macrophage crosstalk with myeloid-derived suppressor cells (MDSCs) was examined. Results: TLR2, but not TLR9, was important for preventing S. aureus outgrowth during craniotomy infection, as revealed by the elevated bacterial burden in the brain, galea, and bone flap of TLR2 KO mice concomitant with global reductions in proinflammatory mediator production compared to WT animals. Co-culture of MDSCs with microglia or macrophages, to model interactions in the brain vs. galea, respectively, also revealed a critical role for TLR2 in triggering pro-inflammatory mediator production. Similar to TLR2, caspase-1 KO animals also displayed increased S. aureus titers coincident with reduced pro-inflammatory mediator release, suggestive of pathway cooperativity. Treatment of caspase-1 KO mice with IL-1β microparticles significantly reduced S. aureus burden in the brain and galea compared to empty microparticles, confirming the critical role of IL-1β in limiting S. aureus outgrowth during craniotomy infection.

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The TIR Homologue Lies near Resistance Genes in Staphylococcus aureus, Coupling Modulation of Virulence and Antimicrobial Susceptibility

Cited by 34 publications

References 53 publications

The TIR-domain containing effectors BtpA and BtpB from Brucella abortus impact NAD metabolism

The TIR-domain containing effectors BtpA and BtpB from Brucella abortus impact NAD metabolism

The TIR-domain containing effectors BtpA and BtpB fromBrucella abortusblock energy metabolism

TLR2 and caspase-1 signaling are critical for bacterial containment but not clearance during craniotomy-associated biofilm infection

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