The ancillary protein 1 of Streptococcus pyogenes FCT-1 pili mediates cell adhesion and biofilm formation through heterophilic as well as homophilic interactions.
Gram-positive pili are known to play a role in bacterial adhesion to epithelial cells and in the formation of biofilm microbial communities. In the present study we undertook the functional characterization of the pilus ancillary protein 1 (AP1_M6) from Streptococcus pyogenes isolates expressing the FCT-1 pilus variant, known to be strong biofilm formers. Cell binding and biofilm formation assays using S. pyogenes in-frame deletion mutants, Lactococcus expressing heterologous FCT-1 pili and purified recombinant AP1_M6, indicated that this pilin is a strong cell adhesin that is also involved in bacterial biofilm formation. Moreover, we show that AP1_M6 establishes homophilic interactions that mediate inter-bacterial contact, possibly promoting bacterial colonization of target epithelial cells in the form of three-dimensional microcolonies. Finally, AP1_M6 knockout mutants were less virulent in mice, indicating that this protein is also implicated in GAS systemic infection.
Novartis Vaccines and Diagnostics, Via Fiorentina 1, Siena, Italy.
Marco
M
Becherelli
Andrea G O
AG
Manetti
Scilla
S
Buccato
Elisa
E
Viciani
Laura
L
Ciucchi
Giulia
G
Mollica
Guido
G
Grandi
Imma
I
Margarit
D018829:Adhesins, Bacterial / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001422:Bacterial Adhesion; D018441:Biofilms; D004847:Epithelial Cells / Q000382:microbiology; D036781:Fimbriae Proteins / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D051379:Mice; D017384:Sequence Deletion; D013290:Streptococcal Infections / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*
D018829:Adhesins, Bacterial; D036781:Fimbriae Proteins