title: Click chemistry for the conservation of cellular structures and fluorescent proteins: ClickOx.
abstract: Reactive oxygen species (ROS), including hydrogen peroxide, are known to cause structural damage not only in living, but also in fixed, cells. Copper-catalyzed azide-alkyne cycloaddition (click chemistry) is known to produce ROS. Therefore, fluorescence imaging of cellular structures, such as the actin cytoskeleton, remains challenging when combined with click chemistry protocols. In addition, the production of ROS substantially weakens the fluorescence signal of fluorescent proteins. This led us to develop ClickOx, which is a new click chemistry protocol for improved conservation of the actin structure and better conservation of the fluorescence signal of green fluorescent protein (GFP)-fusion proteins. Herein we demonstrate that efficient oxygen removal by addition of an enzymatic oxygen scavenger system (ClickOx) considerably reduces ROS-associated damage during labeling of nascent DNA with ATTO 488 azide by Cu(I)-catalyzed click chemistry. Standard confocal and super-resolution fluorescence images of phalloidin-labeled actin filaments and GFP/yellow fluorescent protein-labeled cells verify the conservation of the cytoskeleton microstructure and fluorescence intensity, respectively. Thus, ClickOx can be used advantageously for structure preservation in conventional and most notably in super-resolution microscopy methods.
authors.affiliation: Department of Biotechnology and Biophysics, Julius-Maximilians-Universität Würzburg, Biozentrum, Würzburg, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Löschberger
authors.forename: Thomas
authors.initials: T
authors.lastname: Niehörster
authors.forename: Markus
authors.initials: M
authors.lastname: Sauer
mesh_terms: D000818:Animals; D002460:Cell Line; D022082:Cellular Structures / Q000648:ultrastructure*; D057930:Click Chemistry / Q000379:methods*; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000737:chemistry*; D006801:Humans; D051379:Mice; D018613:Microscopy, Confocal; D057054:Molecular Imaging / Q000379:methods*; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000737:chemistry / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D049452:Green Fluorescent Proteins; D004247:DNA; D010100:Oxygen
keywords: Actin cytoskeleton; Click chemistry; Reactive oxygen species; Super-resolution imaging; dSTORM