Imaging a Single Bacteriophage Extruding From Living Bacteria 01/16/2014 Jesse Jenkins Using the newest nano-bio-imaging technology, researchers have generated the first direct high-resolution images of bacteriophages extruding from living bacteria. Read more... Tweet Force-distance-based imaging methods offer biologists a powerful way to map the biophysical properties of their samples at the nanometer scale. However, these methods have long suffered from poor temporal and lateral resolution, limiting their use in mapping complex biological processes. Now for the first time, researchers at Université Catholique de Louvain (UCL) in Belgium have advanced a force-distance (FD) curve-based atomic force microscopy (AFM) method to map the escape of a single phage from the cell wall of Escherichia coli. The authors claim their new technique could allow researchers to map the molecular interactions of a wealth of complex biosystems, from viruses to tissues. Single bacteriophages extruding from living bacteria imaged with force-distance curve-based AFM Their article, “Multiparametric Atomic Force Microscopy Imaging of Single Bacteriophages Extruding From Living Bacteria,” appeared in Nature Communications. “We feel the paper is outstanding both from the technical and biological perspectives,” said Yves Dufre^ne, professor at UCL Institute of Life Sciences, who led the study. “To our knowledge, this is the first time that anyone has imaged the sites of assembly and extrusion of single phages in live bacteria.” “This is proof that it is possible to scan living bacteria at very high resolution,” added Patrice Soumillion, who researches the biochemistry and molecular genetics of bacteria at UCL and is an author of the study. “AFM technology is developing more and more, so there could be potential applications to monitor other kinds of viral extrusion, maybe on the surface of mammalian cells.” The unique images of filamentous bacteriophages extruding from living bacteria were captured in detail with the help of a technique known as “multiparametric AFM imaging.” Dufre^ne’s team largely credits the technical performance highlighted in the paper to recent breakthroughs in AFM technology. “We tried several years ago to map the extrusion of single phages but the technique at that time was too slow and the resolution too low to enable us to succeed,” explained David Alsteens, post-doctoral researcher at UCL and the study’s first author. “Now, we are able to obtain true correlation of topography with other quantitative measurements like adhesion and mechanical properties. To test their technique, Dufre^ne and colleagues produced a bacterial strain infected with the phage bearing a polyhistidine tag on its extremity. Next, the team introduced a biochemically sensitive AFM tip that would be able to bind to the phage’s polyhistidine tag. Then, the team placed an AFM tip mounted on an inverted optical microscope on the top of a bacterium, allowing them to record force curve data while correlating the new information with fluorescence images In the end, Dufre^ne’s team showed they could image single receptor sites and sample elasticity on living cells. Their results revealed that the sites of phage assembly and extrusion are localized near the bacterial septum in the form of soft nanodomains surrounded by stiffer cell wall material. “Because our technique allows mapping of single receptor sites and sample elasticity on living cells, it may thereby help answer key questions in cell biology, such as the molecular mechanisms of cell adhesion and cell growth,” explained Dufre^ne. Reference: Alsteens D, Trabelsi H, Soumillion P, Dufrêne YF. Multiparametric atomic force microscopy imaging of single bacteriophages extruding from living bacteria. Nat Commun. 2013 Dec 13;4:2926. doi: 10.1038/ncomms3926. Keywords: atomic force microscopy bacteriophage
Posted on: Fri, 17 Jan 2014 14:13:20 +0000
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