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J Biol Chem. 2014 Jun 13;289(24):16988-97. doi: 10.1074/jbc.M114.555854. Epub 2014 Apr 21.

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

Author information

1
From 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.
2
From 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 Brazilian National Laboratory for Biosciences (LNBio), CNPEM, Campinas, 13083-100 São Paulo, Brazil andrea.dessen@ibs.fr.

Abstract

Pili are surface-attached, fibrous virulence factors that play key roles in the pathogenesis process of a number of bacterial agents. Streptococcus pneumoniae is a causative agent of pneumonia and meningitis, and the appearance of drug-resistance organisms has made its treatment challenging, especially in developing countries. Pneumococcus-expressed pili are composed of three structural proteins: RrgB, which forms the polymerized backbone, RrgA, the tip-associated adhesin, and RrgC, which presumably associates the pilus with the bacterial cell wall. Despite the fact that the structures of both RrgA and RrgB were known previously, structural information for RrgC was still lacking, impeding the analysis of a complete model of pilus architecture. Here, we report the structure of RrgC to 1.85 Å and reveal that it is a three-domain molecule stabilized by two intradomain isopeptide bonds. RrgC does not depend on pilus-specific sortases to become attached to the cell wall; instead, it binds the preformed pilus to the peptidoglycan by employing the catalytic activity of SrtA. A comprehensive model of the type 1 pilus from S. pneumoniae is also presented.

KEYWORDS:

Bacterial Adhesion; Bacterial Toxin; Crystal Structure; Infectious Disease; Virulence Factor

PMID:
24755220
PMCID:
PMC4059141
DOI:
10.1074/jbc.M114.555854
[Indexed for MEDLINE]
Free PMC Article

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