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Pathogenic Streptococcus strains employ novel escape strategy to inhibit bacteriostatic effect mediated by mammalian

Jing Wang1, Youjun Feng2, Changjun Wang3

  • 1Translational Medicine Center, PLA Hospital No.454, Nanjing, China.

Cellular Microbiology
|January 17, 2017
PubMed

Insights

Pathogenic Streptococci use a novel SP1 protein secreted via a type-IVC secretion system to evade host innate immunity. This interaction with peptidoglycan recognition protein-1 (PGLYRP-1) offers new antimicrobial drug targets.

Area of Science:

  • Microbiology
  • Immunology
  • Molecular Biology

Background:

  • Pathogenic streptococci cause severe infections in animals and humans.
  • A pathogenicity island (PAI) with a type-IVC secretion system is linked to virulent Streptococcus suis infections.
  • This system secretes effectors causing streptococcal toxic shock syndrome.

Purpose of the Study:

  • To identify new PAI families in streptococcal species.
  • To investigate the function of a novel PPIase molecule, SP1, within a PAI.
  • To understand how pathogenic Streptococci evade innate immunity.

Main Methods:

  • Genomic analysis to identify new PAI families.
  • Biochemical assays to study protein interactions.
  • Functional assays to assess immune evasion mechanisms.

Main Results:

  • A new PAI family containing a type-IVC secretion system and SP1 was identified across three streptococcal species.
  • SP1 directly interacts with peptidoglycan recognition protein-1 (PGLYRP-1).
  • SP1 disrupts the PGLYRP-1-mediated bacteriostatic effect, enabling bacterial immune evasion.

Conclusions:

  • Pathogenic Streptococci utilize the secreted SP1 protein to antagonize PGLYRP-1, a key innate immune component.
  • This mechanism represents a novel bacterial strategy for escaping host immune defenses.
  • The SP1-PGLYRP-1 interaction presents a potential target for developing novel antimicrobial therapies against resistant bacteria.
Keywords:
GI-type-IVC secretion systemPAIPGRPStreptococcus

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