Abstract
In Gram-positive bacteria, sortase-dependent pili mediate the adhesion of bacteria to host epithelial cells and play a pivotal role in colonization, host signaling, and biofilm formation. Lactobacillus rhamnosus strain GG, a well known probiotic bacterium, also displays on its cell surface mucus-binding pilus structures, along with other LPXTG surface proteins, which are processed by sortases upon specific recognition of a highly conserved LPXTG motif. Bioinformatic analysis of all predicted LPXTG proteins encoded by the L. rhamnosus GG genome revealed a remarkable conservation of glycine residues juxtaposed to the canonical LPXTG motif. Here, we investigated and defined the role of this so-called triple glycine (TG) motif in determining sortase specificity during the pilus assembly and anchoring. Mutagenesis of the TG motif resulted in a lack or an alteration of the L. rhamnosus GG pilus structures, indicating that the TG motif is critical in pilus assembly and that they govern the pilin-specific and housekeeping sortase specificity. This allowed us to propose a regulatory model of the L. rhamnosus GG pilus biogenesis. Remarkably, the TG motif was identified in multiple pilus gene clusters of other Gram-positive bacteria, suggesting that similar signaling mechanisms occur in other, mainly pathogenic, species.
Original language | English |
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Pages (from-to) | 15764-15775 |
Number of pages | 12 |
Journal | Journal of Biological Chemistry |
Volume | 289 |
Issue number | 22 |
DOIs | |
Publication status | Published - 30 May 2014 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Bacterial Adhesion
- Electron Microscopy (EM)
- Protein Motif
- Signaling
- Site-directed Mutagenesis
- COMPLETE GENOME SEQUENCE
- GRAM-POSITIVE BACTERIA
- ENTEROCOCCUS-FAECIUM ISOLATE
- GROUP-B STREPTOCOCCUS
- LACTIC-ACID BACTERIA
- LACTOCOCCUS-LACTIS
- CORYNEBACTERIUM-DIPHTHERIAE
- BACILLUS-ANTHRACIS
- PILIN SUBUNIT
- REVEALS PILI