Exploring the Bacterial Envelope and Model Biomembranes with AFM

VELA, MARÍA ELENA

MICROSCOPY & MICROANALYSIS

CAMBRIDGE UNIV PRESS

Año: 2020 vol. 26 p. 71 - 72

1431-9276

Atomic Force Microscopy (AFM) is a powerful tool for visualizing the morphology of cellsand membranes in buffer solution and Force Spectroscopy (FS) allows analyzing thelocalization, interactions and mechanical properties of their individual components.We have studied the nanomechanical properties of the cell envelope down to the molecularlevel of Bordetella Pertussis, a pathogenic bacteria responsible of whooping cough, a highlyinfectious disease. A relationship between stiffness and adhesin clusters was established.Antibiotic-effect on individual and grouped bacteria was followed by topographic andnanomechanical properties and the beneficial effect of consortiums to resist differenttherapeutic strategies was examined.1Regarding model biomembranes, Force Spectroscopy (FS) was used to discriminate differentphases that coexist in the ternary lipid mixture (DOPC/ 16:0-SM/Cho) that exhibits phasecoexistence, i.e. a liquid-ordered (Lo) phase enriched in sphingomyelin (SM) and cholesterol(Cho) which is segregated from the liquid-disordered (Ld) phase composed mainly of DOPC.This ternary lipid mixture mimics lipid raft-like domains. Supported lipid bilayers (SLBs)were formed on mica and Au Surface Plasmon Resonance(SPR) sensor chips. The presenceof different lipid phases was characterized by topographic AFM images and by FS.2 Thenanomechanical properties of SLBs formed on polycrystalline Au were comparable to theones obtained on a flat mica substrate which corroborates the adequate formation of SLBs onAu chips. This finding opens a great variety of studies concerning interactions of modelbiomembranes with biomolecules, surfactants and nanomaterials among other systems bySPR.