Staphylococcal superantigen-like protein 10 (SSL10) binds to human immunoglobulin G (IgG) and inhibits complement activation via the classical pathway

Itoh, Saotomo; Hamada, Eri; Kamoshida, Go; Yokoyama, Ryosuke; Takii, Takemasa; Onozaki, Kikuo; Tsuji, Tsutomu

doi:10.1016/j.molimm.2009.09.027

Cited by 79 publications

(69 citation statements)

References 28 publications

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“…Interestingly, the functions that have been discovered for SSLs so far have all been linked to immune evasion. SSL5 inhibits neutrophil extravasation (17,18) and phagocyte function (19,20), SSL7 binds IgA and inhibits complement (21), and SSL10 inhibits IgG1-mediated phagocytosis (22,23), blood coagulation (24), and the chemokine receptor CXCR4 (25). In addition to SSL3, also weak TLR2 inhibitory activity was observed for SSL4 (5), but it remains unknown whether that is its dominant function.…”

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confidence: 99%

Structural basis for inhibition of TLR2 by staphylococcal superantigen-like protein 3 (SSL3)

Koymans

Feitsma

Brondijk

et al. 2015

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

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Toll-like receptors (TLRs) are crucial in innate recognition of invading micro-organisms and their subsequent clearance. Bacteria are not passive bystanders and have evolved complex evasion mechanisms. Staphylococcus aureus secretes a potent TLR2 antagonist, staphylococcal superantigen-like protein 3 (SSL3), which prevents receptor stimulation by pathogen-associated lipopeptides. Here, we present crystal structures of SSL3 and its complex with TLR2. The structure reveals that formation of the specific inhibitory complex is predominantly mediated by hydrophobic contacts between SSL3 and TLR2 and does not involve interaction of TLR2-glycans with the conserved Lewis X binding site of SSL3. In the complex, SSL3 partially covers the entrance to the lipopeptide binding pocket in TLR2, reducing its size by ∼50%. We show that this is sufficient to inhibit binding of agonist Pam 2 CSK 4 effectively, yet allows SSL3 to bind to an already formed TLR2-Pam 2 CSK 4 complex. The binding site of SSL3 overlaps those of TLR2 dimerization partners TLR1 and TLR6 extensively. Combined, our data reveal a robust dual mechanism in which SSL3 interferes with TLR2 activation at two stages: by binding to TLR2, it blocks ligand binding and thus inhibits activation. Second, by interacting with an already formed TLR2-lipopeptide complex, it prevents TLR heterodimerization and downstream signaling.S. aureus | Toll-like receptor | immune evasion | innate immunity | crystal structure

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confidence: 99%

Structural basis for inhibition of TLR2 by staphylococcal superantigen-like protein 3 (SSL3)

Koymans

Feitsma

Brondijk

et al. 2015

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

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“…In S. aureus, a large arsenal of complement evasion molecules have been identified. These include secreted factors that block several steps of the complement cascade: staphylococcal superantigen-like protein 10 inhibits CP activation (16); staphylococcal complement inhibitor (SCIN) (17), extracellular fibrinogenbinding protein, and extracellular complement-binding protein block C3/C5 conversion by convertases (18); staphylococcal superantigen-like protein 7 inhibits C5 conversion (19); and chemotaxis inhibitory protein of S. aureus (CHIPS) inhibits C5a-dependent neutrophil chemotaxis by binding to the C5a receptor (C5aR) (20). Next to these secreted molecules, S. aureus also produces several surface proteins that interact with the complement system: staphylococcal IgG-binder binds both IgG and C3 to prevent classical and alternative complement activation (21,22), and clumping factor A and the iron-regulated surface determinant protein H promote degradation of opsonic C3b (23,24).…”

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confidence: 99%

Staphylococcus aureus Metalloprotease Aureolysin Cleaves Complement C3 To Mediate Immune Evasion

Laarman

Ruyken

Malone

et al. 2011

The Journal of Immunology

172

126

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Complement is one of the first host defense barriers against bacteria. Activated complement attracts neutrophils to the site of infection and opsonizes bacteria to facilitate phagocytosis. The human pathogen Staphylococcus aureus has successfully developed ways to evade the complement system, for example by secretion of specific complement inhibitors. However, the influence of S. aureus proteases on the host complement system is still poorly understood. In this study, we identify the metalloprotease aureolysin as a potent complement inhibitor. Aureolysin effectively inhibits phagocytosis and killing of bacteria by neutrophils. Furthermore, we show that aureolysin inhibits the deposition of C3b on bacterial surfaces and the release of the chemoattractant C5a. Cleavage analyses show that aureolysin cleaves the central complement protein C3. Strikingly, there was a clear difference between the cleavages of C3 in serum versus purified conditions. Aureolysin cleaves purified C3 specifically in the α-chain, close to the C3 convertase cleavage site, yielding active C3a and C3b. However, in serum we observe that the aureolysin-generated C3b is further degraded by host factors. We pinpointed these factors to be factor H and factor I. Using an aureolysin mutant in S. aureus USA300, we show that aureolysin is essential and sufficient for C3 cleavage by bacterial supernatant. In short, aureolysin acts in synergy with host regulators to inactivate C3 thereby effectively dampening the host immune response.

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“…SSL10 binds to chemokine receptors and inhibits chemotaxis of tumor cells (32). SSL10 also binds to human IgG and inhibits the interaction of IgG with complement C1q and the Fc␥ receptor (16,23). However, the target molecules of the remaining SSLs have not been identified.…”

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confidence: 99%

Staphylococcal Superantigen-Like Protein 3 Binds to the Toll-Like Receptor 2 Extracellular Domain and Inhibits Cytokine Production Induced by Staphylococcus aureus, Cell Wall Component, or Lipopeptides in Murine Macrophages

et al. 2012

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c Staphylococcal superantigen-like proteins (SSLs) are a family of exoproteins sharing structural similarity with superantigens, but no superantigenic activity. Corresponding host target proteins or receptors against a portion of SSLs in the family have been identified. In this study, we show that SSL3 specifically binds to Toll-like receptor 2 (TLR2) and inhibits the stimulation of macrophages by TLR2 ligands. An approximately 100-kDa protein was recovered by using recombinant His-tagged SSL3-conjugated Sepharose from the lysate of porcine spleen, and the protein was identified as porcine TLR2 by peptide mass fingerprinting analysis. The SSL3-conjugated Sepharose recovered human and mouse TLR2 but not TLR4 from human neutrophils and mouse macrophage RAW 264.7 cells, as well as a recombinant TLR2 extracellular domain chimera protein. The production levels of interleukin 12 (IL-12) from mouse macrophages treated with heat-killed Staphylococcus aureus and of tumor necrosis factor alpha (TNF-␣) from RAW 264.7 cells induced by peptidoglycan or lipopeptide TLR2 ligands were strongly suppressed in the presence of SSL3. The mutation of consensus sialic acid-containing glycan-binding residues in SSL3 did not abrogate the binding ability to TLR2 or inhibitory activity on TLR2, indicating that the interaction of SSL3 with TLR2 was independent of the sialic acid-containing glycan-binding residues. These findings demonstrate that SSL3 is able to bind the extracellular domain of TLR2 and interfere with TLR2 function. The present study provides a novel mechanism of SSL3 in immune evasion of S. aureus via interfering with its recognition by innate immune cells.

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Staphylococcal superantigen-like protein 10 (SSL10) binds to human immunoglobulin G (IgG) and inhibits complement activation via the classical pathway

Cited by 79 publications

References 28 publications

Structural basis for inhibition of TLR2 by staphylococcal superantigen-like protein 3 (SSL3)

Structural basis for inhibition of TLR2 by staphylococcal superantigen-like protein 3 (SSL3)

Staphylococcus aureus Metalloprotease Aureolysin Cleaves Complement C3 To Mediate Immune Evasion

Staphylococcal Superantigen-Like Protein 3 Binds to the Toll-Like Receptor 2 Extracellular Domain and Inhibits Cytokine Production Induced by Staphylococcus aureus, Cell Wall Component, or Lipopeptides in Murine Macrophages

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