Yves F. Dufrêne

Bio: Yves F. Dufrêne is an academic researcher from Université catholique de Louvain. The author has contributed to research in topics: Force spectroscopy & Adhesion. The author has an hindex of 82, co-authored 315 publications receiving 20046 citations. Previous affiliations of Yves F. Dufrêne include Catholic University of Leuven & Gembloux Agro-Bio Tech.

Detection and localization of single molecular recognition events using atomic force microscopy

Abstract: Because of its piconewton force sensitivity and nanometer positional accuracy, the atomic force microscope (AFM) has emerged as a powerful tool for exploring the forces and the dynamics of the interaction between individual ligands and receptors, either on isolated molecules or on cellular surfaces. These studies require attaching specific biomolecules or cells on AFM tips and on solid supports and measuring the unbinding forces between the modified surfaces using AFM force spectroscopy. In this review, we describe the current methodology for molecular recognition studies using the AFM, with an emphasis on strategies available for preparing AFM tips and samples, and on procedures for detecting and localizing single molecular recognition events.

Atomic force microscopy as a multifunctional molecular toolbox in nanobiotechnology

Abstract: With its ability to observe, manipulate and explore the functional components of the biological cell at subnanometre resolution, atomic force microscopy (AFM) has produced a wealth of new opportunities in nanobiotechnology. Evolving from an imaging technique to a multifunctional 'lab-on-a-tip', AFM-based force spectroscopy is increasingly used to study the mechanisms of molecular recognition and protein folding, and to probe the local elasticity, chemical groups and dynamics of receptor-ligand interactions in live cells. AFM cantilever arrays allow the detection of bioanalytes with picomolar sensitivity, opening new avenues for medical diagnostics and environmental monitoring. Here we review the fascinating opportunities offered by the rapid advances in AFM.

Imaging modes of atomic force microscopy for application in molecular and cell biology

Abstract: Atomic force microscopy (AFM) is a powerful, multifunctional imaging platform that allows biological samples, from single molecules to living cells, to be visualized and manipulated. Soon after the instrument was invented, it was recognized that in order to maximize the opportunities of AFM imaging in biology, various technological developments would be required to address certain limitations of the method. This has led to the creation of a range of new imaging modes, which continue to push the capabilities of the technique today. Here, we review the basic principles, advantages and limitations of the most common AFM bioimaging modes, including the popular contact and dynamic modes, as well as recently developed modes such as multiparametric, molecular recognition, multifrequency and high-speed imaging. For each of these modes, we discuss recent experiments that highlight their unique capabilities.

Nanoscale mapping of the elasticity of microbial cells by atomic force microscopy

Abstract: Single microbial cells can show important local variations of elasticity due to the complex, anisotropic composition of their walls. An example of this is the yeast during cell division, where chitin is known to accumulate in the localized region of the cell wall involved in budding. We used atomic force microscopy (AFM) to measure quantitatively the local mechanical properties of hydrated yeast cells. Topographic images and spatially resolved force maps revealed significant lateral variations of elasticity across the cell surface, the bud scar region being significantly stiffer than the surrounding cell wall. To get quantitative information on sample elasticity, force curves were converted into force vs indentation curves. The curves were then fitted with the Hertz model, yielding Young's modulus values of 6.1 +/- 2.4 and 0.6 +/- 0.4 MPa for the bud scar and surrounding cell surface, respectively. These data lead us to conclude that in yeast, the bud scar is 10 times stiffer than the surrounding cell wall, a finding which is consistent with the accumulation of chitin in the bud scar region. This is the first report in which spatially resolved AFM force curves are used to distinguish regions of different elasticity at the surface of single microbial cells in relation with function (i.e., cell division). In future research, this approach will provide fundamental insights into the spatial distribution of physical properties at heterogeneous microbial cell surfaces.

Force probing surfaces of living cells to molecular resolution

Abstract: Biological processes rely on molecular interactions that can be directly measured using force spectroscopy techniques. Here we review how atomic force microscopy can be applied to force probe surfaces of living cells to single-molecule resolution. Such probing of individual interactions can be used to map cell surface receptors, and to assay the receptors' functional states, binding kinetics and landscapes. This information provides unique insight into how cells structurally and functionally modulate the molecules of their surfaces to interact with the cellular environment.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Initiation of biofilm formation in Pseudomonas fluorescens WCS365 proceeds via multiple, convergent signalling pathways: a genetic analysis

Abstract: Populations of surface-attached microorganisms comprising either single or multiple species are commonly referred to as biofilms. Using a simple assay for the initiation of biofilm formation (e.g. attachment to an abiotic surface) by Pseudomonas fluorescens strain WCS365, we have shown that: (i) P. fluorescens can form biofilms on an abiotic surface when grown on a range of nutrients; (ii) protein synthesis is required for the early events of biofilm formation; (iii) one (or more) extracytoplasmic protein plays a role in interactions with an abiotic surface; (iv) the osmolarity of the medium affects the ability of the cell to form biofilms. We have isolated transposon mutants defective for the initiation of biofilm formation, which we term surface attachment defective (sad). Molecular analysis of the sad mutants revealed that the ClpP protein (a component of the cytoplasmic Clp protease) participates in biofilm formation in this organism. Our genetic analyses suggest that biofilm formation can proceed via multiple, convergent signalling pathways, which are regulated by various environmental signals. Finally, of the 24 sad mutants analysed in this study, only three had defects in genes of known function. This result suggests that our screen is uncovering novel aspects of bacterial physiology.

Single-molecule force spectroscopy: optical tweezers, magnetic tweezers and atomic force microscopy

Abstract: Single-molecule force spectroscopy has emerged as a powerful tool to investigate the forces and motions associated with biological molecules and enzymatic activity. The most common force spectroscopy techniques are optical tweezers, magnetic tweezers and atomic force microscopy. Here we describe these techniques and illustrate them with examples highlighting current capabilities and limitations.