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Structural basis of pilus anchoring by the ancillary pilin RrgC of Streptococcus pneumoniae

Md Munan Shaik1, Amandine Maccagni1, Guillaume Tourcier1

  • 1From the Institut de Biologie Structurale (IBS), Université Grenoble Alpes, 41 avenue des Martyrs, 38044 Grenoble, France, the Commissariat à l'Energie Atomique (CEA), 38000 Grenoble, France, the Centre National de la Recherche Scientifique (CNRS), UMR 5075, Grenoble, France, and.

The Journal of Biological Chemistry
|April 24, 2014
PubMed

Insights

Streptococcus pneumoniae pili are crucial for infection. Researchers determined the structure of RrgC, a key pilus protein, revealing its role in attaching pili to bacterial cell walls, aiding in understanding pneumococcal pathogenesis.

Area of Science:

  • Microbiology
  • Structural Biology
  • Biochemistry

Background:

  • Pili are essential virulence factors in bacterial pathogenesis.
  • Streptococcus pneumoniae causes pneumonia and meningitis, with increasing drug resistance posing treatment challenges.
  • Understanding pneumococcal pilus structure is vital for developing new therapeutic strategies.

Purpose of the Study:

  • To determine the structure of the RrgC protein, a component of Streptococcus pneumoniae pili.
  • To elucidate the mechanism by which RrgC mediates pilus attachment to the bacterial cell wall.
  • To present a comprehensive model of the type 1 pilus from S. pneumoniae.

Main Methods:

  • X-ray crystallography was used to determine the 1.85 Å structure of RrgC.
  • Biochemical assays were employed to investigate the role of SrtA in pilus anchoring.
  • Bioinformatic analysis and molecular modeling were used to construct a comprehensive pilus model.

Main Results:

  • The structure of RrgC revealed a three-domain molecule stabilized by two intradomain isopeptide bonds.
  • RrgC attaches pili to the peptidoglycan layer via the catalytic activity of SrtA, independent of pilus-specific sortases.
  • A complete model of the type 1 pilus from S. pneumoniae was generated, integrating structural and functional data.

Conclusions:

  • The determined RrgC structure provides critical insights into pneumococcal pilus assembly and architecture.
  • The findings highlight a novel mechanism for pilus anchoring to the bacterial cell wall, involving SrtA.
  • This study advances our understanding of S. pneumoniae pathogenesis and offers potential targets for antimicrobial development.
Keywords:
Bacterial AdhesionBacterial ToxinCrystal StructureInfectious DiseaseVirulence Factor

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