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Streptococcus pyogenes cytolysin-mediated translocation does not require pore formation by streptolysin O

N'Goundo Magassa1, Sukantha Chandrasekaran, Michael G Caparon

  • 1Department of Molecular Microbiology, Washington University School of Medicine, St Louis, Missouri 63110-1093, USA.

EMBO Reports
|March 27, 2010
PubMed

Insights

Streptococcus pyogenes toxin translocation (CMT) can occur without pore formation, but cell death requires the streptolysin O (SLO) pore. This study clarifies the distinct roles of SLO pore formation in bacterial pathogenesis.

Area of Science:

  • Microbiology
  • Cell Biology
  • Bacterial Pathogenesis

Background:

  • Bacterial toxins are crucial for virulence, with Cytolysin-mediated translocation (CMT) involving pore-forming toxins like streptolysin O (SLO) from Streptococcus pyogenes.
  • SLO translocates the S. pyogenes nicotinamide adenine dinucleotide-glycohydrolase (SPN) into host cells, leading to cell death.
  • Previous research indicated pore formation alone is insufficient for CMT, leaving the SLO pore's role unclear.

Purpose of the Study:

  • To investigate the necessity of SLO pore formation for SPN translocation and host cell cytotoxicity.
  • To elucidate the mechanism of CMT and its relationship with host cell processes.

Main Methods:

  • Construction and analysis of Streptococcus pyogenes strains expressing modified SLO proteins with varying pore-forming abilities.
  • Assessment of SPN translocation efficiency in these mutant strains.
  • Evaluation of cytotoxicity assays following inhibition of actin polymerization to probe the role of endocytosis.

Main Results:

  • SLO mutants incapable of pore formation still effectively translocated SPN into host cells.
  • SPN translocation was observed to occur independently of actin polymerization, suggesting a mechanism distinct from clathrin-mediated endocytosis.
  • Cytotoxicity, however, was dependent on the pore-forming capability of SLO, even when SPN translocation was intact.

Conclusions:

  • SLO pore formation is not essential for the translocation of SPN during CMT.
  • The cytotoxic effects of CMT are critically dependent on SLO's pore-forming activity.
  • CMT represents a complex mechanism where translocation and cytotoxicity are regulated by distinct functions of SLO.

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