BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Memento EPFL// BEGIN:VEVENT SUMMARY:Schläfli Prize 2023 DTSTART:20230928T161500 DTEND:20230928T180000 DTSTAMP:20260404T062830Z UID:cdb098945fbf672cab08bc30646533f333d5223d0cf6c6289bd131cd CATEGORIES:Conferences - Seminars DESCRIPTION:Michelle Frei\nChemigenetic tools for live-cell fluorescence m icroscopy\n\nSelf-labeling protein tags have become critical tools in fluo rescence microscopy. Their use in combination with fluorogenic fluorophore s\, which only become fluorescent when bound to their protein target\, mak es them particularly suitable for live-cell applications. The increase in fluorescence observed upon labeling and the photophysical properties of th e fluorophore are mainly determined by the protein surface near the fluoro phore binding site. However\, most effort has been invested in the develop ment of new fluorophores and little attention has been paid to the enginee ring of the self-labeling protein tag.\nHere\, we report on the engineerin g of HaloTag7 to modulate the photophysical properties of the bound rhodam ines. Specifically\, we developed a series of new HaloTag variants with al tered brightness and lifetime properties in comparison to HaloTag7. The ge nerated HaloTag variants are labeled with a single fluorophore but show di stinct fluorescence lifetimes. This renders them distinguishable by fluore scence lifetime imaging microscopy (FLIM)\, enabling live-cell multiplexin g of three targets in one spectral channel. Fluorescence lifetime multiple xing previously required the fastidious investigation of the fluorescence lifetime of each fluorophore. The introduced HaloTag series simplifies thi s task tremendously offering the first generalized strategy to create life time contrast in living cells. Additionally\, we used the differences in f luorescence lifetime to generate a chemigenetic fluorescence lifetime base d biosensor to monitor cell cycle progression.\nOverall\, our work highlig hts that the combination of protein engineering and chemical synthesis can generate imaging tools with outstanding properties. We expect the HaloTag series will facilitate the widespread use of FLIM and enable researchers to increase the number of targets measured simultaneously. This will ultim ately enhance our understanding of multifactorial biological processes. LOCATION:CO 3 https://plan.epfl.ch/?room==CO%203 STATUS:CONFIRMED END:VEVENT END:VCALENDAR