Localization of adhesins on the surface of a pathogenic bacterial envelope through atomic force microscopy

LAURA ARNAL; G. LONGO; P. STUPAR; MARCOS F. CASTEZ; N. CATTELAN; ROBERTO C. SALVAREZZA; O. M. YANTORNO; S. KASAS; MARÍA E. VELA

NANOSCALE

The Royal Society of Chemistry

Año: 2015 vol. 7 p. 17563 - 17572

2040-3364

Bacterial adhesion is the first and a significant step in establishing infection. This adhesion normallyoccurs in the presence of flow of fluids. Therefore, bacterial adhesins must be able to provide highstrength interactions with their target surface in order to maintain the adhered bacteria under hydro-mechanical stressing conditions. In the case of B. pertussis, a Gram-negative bacterium responsible forpertussis, a highly contagious human respiratory tract infection, an important protein participating in theadhesion process is a 220 kDa adhesin named filamentous haemagglutinin (FHA), an outer membraneand also secreted protein that contains recognition domains to adhere to ciliated respiratory epithelialcells and macrophages. In this work, we obtained information on the cell-surface localization and distri-bution of the B. pertussis adhesin FHA using an antibody-functionalized AFM tip. Through the analysis ofspecific molecular recognition events we built a map of the spatial distribution of the adhesin whichrevealed a non-homogeneous pattern. Moreover, our experiments showed a force induced reorganiz-ation of the adhesin on the surface of the cells, which could explain a reinforced adhesive response underexternal forces. This single-molecule information contributes to the understanding of basic molecularmechanisms used by bacterial pathogens to cause infectious disease and to gain insights into the struc-tural features by which adhesins can act as force sensors under mechanical shear conditions.