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Intracellular Staphylococcus aureus employs the cysteine protease staphopain A to induce host cell death in epithelial cells.

ABSTRACT: Staphylococcus aureus is a major human pathogen, which can invade and survive in non-professional and professional phagocytes. Uptake by host cells is thought to contribute to pathogenicity and persistence of the bacterium. Upon internalization by epithelial cells, cytotoxic S. aureus strains can escape from the phagosome, replicate in the cytosol and induce host cell death. Here, we identified a staphylococcal cysteine protease to induce cell death after translocation of intracellular S. aureus into the host cell cytoplasm. We demonstrated that loss of staphopain A function leads to delayed onset of host cell death and prolonged intracellular replication of S. aureus in epithelial cells. Overexpression of staphopain A in a non-cytotoxic strain facilitated intracellular killing of the host cell even in the absence of detectable intracellular replication. Moreover, staphopain A contributed to efficient colonization of the lung in a mouse pneumonia model. In phagocytic cells, where intracellular S. aureus is exclusively localized in the phagosome, staphopain A did not contribute to cytotoxicity. Our study suggests that staphopain A is utilized by S. aureus to exit the epithelial host cell and thus contributes to tissue destruction and dissemination of infection.

SUBMITTER: Stelzner K

PROVIDER: S-EPMC8443034 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Activation of Human Platelets by <i>Staphylococcus aureus</i> Secreted Protease Staphopain A.

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Crystal Structure of Staphopain C from <i>Staphylococcus aureus</i>.

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Intracellular Staphylococcus aureus perturbs the host cell Ca2+-homeostasis to promote cell death

Project description:The pathogen Staphylococcus aureus can invade and survive within human cells. There, the intracellular bacterium induces host cell death, which may facilitate spread of infection and tissue destruction. We here conducted a shRNA screen and infected the library of knock-down cells with S. aureus. We identified calcium signaling pathways to play a role in S. aureus invasion and cytotoxicity. For latter, the intracellular bacteria induce a cytoplasmic and mitochondrial Ca2+-overload, which results in host cell death.

2021-10-31 | GSE156073 | GEO

Intracellular Staphylococcus aureus persisters upon antibiotic exposure

Project description:Bacterial persister cells are phenotypic variants that exhibit a transient non-growing state and antibiotic tolerance. Here we provide in vitro evidence of Staphylococcus aureus persisters within infected host cells. We show that the bacteria surviving antibiotic treatment within host cells are persisters, displaying biphasic killing and reaching a uniformly non-responsive, non-dividing state when followed at the single-cell level. This phenotype is stable but reversible upon antibiotic removal. Intracellular S. aureus persisters remain metabolically active, but display an altered transcriptomic profile consistent with activation of stress responses, including the stringent response as well as cell-wall stress, SOS and heat-shock responses. These changes are associated with multidrug tolerance after exposure to a single antibiotic. We hypothesize that intracellular S. aureus persisters may constitute a reservoir for relapsing infection, and could contribute to therapeutic failures.

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Role of a cysteine synthase in Staphylococcus aureus.

Project description:The gram-positive human pathogen Staphylococcus aureus is often isolated with media containing potassium tellurite, to which it has a higher level of resistance than Escherichia coli. The S. aureus cysM gene was isolated in a screen for genes that would increase the level of tellurite resistance of E. coli DH5alpha. The protein encoded by S. aureus cysM is sequentially and functionally homologous to the O-acetylserine (thiol)-lyase B family of cysteine synthase proteins. An S. aureus cysM knockout mutant grows poorly in cysteine-limiting conditions, and analysis of the thiol content in cell extracts showed that the cysM mutant produced significantly less cysteine than wild-type S. aureus SH1000. S. aureus SH1000 cannot use sulfate, sulfite, or sulfonates as the source of sulfur in cysteine biosynthesis, which is explained by the absence of genes required for the uptake and reduction of these compounds in the S. aureus genome. S. aureus SH1000, however, can utilize thiosulfate, sulfide, or glutathione as the sole source of sulfur. Mutation of cysM caused increased sensitivity of S. aureus to tellurite, hydrogen peroxide, acid, and diamide and also significantly reduced the ability of S. aureus to recover from starvation in amino acid- or phosphate-limiting conditions, indicating a role for cysteine in the S. aureus stress response and survival mechanisms.

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Intracellular Staphylococcus aureus persisters upon antibiotic exposure.

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