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Single‐molecule atomic force microscopy unravels the binding mechanism of a B urkholderia cenocepacia trimeric autotransporter adhesin
Author(s) -
ElKiratChatel Sofiane,
MilHomens Dalila,
Beaussart Audrey,
Fialho Arsenio M.,
Dufrêne Yves F.
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12301
Subject(s) - burkholderia cenocepacia , bacterial adhesin , biology , microbiology and biotechnology , biofilm , bacterial outer membrane , burkholderia cepacia complex , adhesion , bacteria , burkholderia , chemistry , escherichia coli , biochemistry , genetics , organic chemistry , gene
Summary Trimeric autotransporter adhesins ( TAAs ) are bacterial surface proteins that fulfil important functions in pathogenic G ram‐negative bacteria. Prominent examples of TAAs are found in B urkholderia cepacia complex, a group of bacterial species causing severe infections in patients with cystic fibrosis. While there is strong evidence that Burkholderia cenocepacia TAAs mediate adhesion, aggregation and colonization of the respiratory epithelium, we still know very little about the molecular mechanisms behind these interactions. Here, we use single‐molecule atomic force microscopy to unravel the binding mechanism of BCAM 0224, a prototype TAA from B . cenocepacia K 56‐2. We show that the adhesin forms homophilic trans‐interactions engaged in bacterial aggregation, and that it behaves as a spring capable to withstand high forces. We also find that BCAM 0224 binds collagen, a major extracellular component of host epithelia. Both homophilic and heterophilic interactions display low binding affinity, which could be important for epithelium colonization. We then demonstrate that BCAM 0224 recognizes receptors on living pneumocytes, and leads to the formation of membrane tethers that may play a role in promoting adhesion. Collectively, our results show that BCAM 0224 is a multifunctional adhesin endowed with remarkable binding properties, which may represent a general mechanism among TAAs for strengthening bacterial adhesion.