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SUMMARY:Cell Penetration and Membrane Fusion: Two Sides of the Same Coin
LOCATION:Chemistry B202
TZID:America/Denver
DTSTART:20193201T000000
UID:2026-05-18-05-28-36@natsci.colostate.edu
DTSTAMP:20260518T052836
Description:About the Seminar\n\nCell penetrating peptides have a unique po
 tential for targeted drug delivery\, therefore\, mechanistic understanding
  of their membrane action has been sought since their discovery over 20 ye
 ars ago. While ATP-driven endocytosis is known to play a major role in the
 ir internalization\, there has been also ample evidence for the importance
  of passive translocation for which the direct mechanism\, where the pepti
 de is thought to directly pass through the membrane via a temporary pore\,
  has been widely advocated. In this talk\, I will question this view and d
 emonstrate that arginine-rich cell penetrating peptides can instead enter 
 vesicles and cells by inducing multilamellarity and fusion\, analogously t
 o the action of calcium ions. The molecular picture of this penetration mo
 de\, which differs qualitatively from the previously proposed direct mecha
 nism\, is provided by molecular dynamics simulations. In addition\, the ki
 netics of vesicle agglomeration and fusion by nonaarginine\, nonalysine\, 
 and calcium ions are documented in real time by fluorescence techniques an
 d the induction of multilamellar phases in vesicles and cells is revealed 
 both via electron microscopy and fluorescence spectroscopy. We thus show t
 hat the newly identified passive cell penetration mechanism is analoguous 
 to vesicle fusion induced by calcium ions\, demonstrating that the two pro
 cesses are of a common mechanistic origin.\n\nAllolio C.\, Magarkar A.\, J
 urkiewiczf P.\, Baxová K.\, Javanainen M.\, Mason P.E.\, Sachl R.\, Cebec
 auer M.\, Hof M.\, Horinek D.\, Heinz V.\, Rachel R.\, Zieglerg C.M.\, Sch
 rofel A.\, Jungwirth P.: Arginine-rich cell-penetrating peptides induce me
 mbrane multilamellarity and subsequently enter via formation of a fusion p
 ore. Proceedings of the National Academy of Sciences USA 115 (2018) 11923.
 \n\nAbout the Speaker\n\nThe Jungwirth Lab aims at gaining molecular level
  understanding of biological processes involving ions using computer simul
 ations in close contact with spectroscopic experiments. Using molecular dy
 namics simulations and quantum chemical methods we are attempting to estab
 lish the mechanisms of ion-protein interactions responsible for the saltin
 g out (Hofmeister) series and beyond. Applications of our research range f
 rom influencing protein aggregation\, precipitation\, or denaturation and 
 controlling enzymatic activity to establishing properties of phospholipid 
 bilayers in the presence of ions. One of the key aims within the latter su
 bject is to establish molecular principles governing the action of calcium
  ions involved in membrane fusion and |cationic cell penetrating peptides 
 (important\, e.g.\, for novel ways of drug delivery to cells). Our related
  research activities concern electron solvation pertinent to radiation che
 mistry and DNA damage. And in our free time we entertain ourselves by \"ba
 lcony experiments\" involving\, for example\, explosions of alkali metals 
 in water\, which also allows us to connect to general public and populariz
 e science.12:00 pm
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