Integrated Calendar

Cell penetrating peptides have a unique potential for targeted drug delivery. While ATP-driven endocytosis is known to play a major role in their internalization, there has been also ample evidence for the importance of passive translocation for which the direct mechanism, where the peptide 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 demonstrate that arginine-rich cell penetrating peptides can instead enter vesicles and cells by inducing multilamellarity and fusion, analogously to the action of calcium ions.

Allolio C., Magarkar A., Jurkiewiczf P., Baxová K., Javanainen M., Mason P.E., Sachl R., Cebecauer M., Hof M., Horinek D., Heinz V., Rachel R., Zieglerg C.M., Schrofel A., Jungwirth P.: Arginine-rich cell-penetrating peptides induce membrane multilamellarity and subsequently enter via formation of a fusion pore. Proceedings of the National Academy of Sciences USA 115 (2018) 11923.

Thermal motions of atoms is an ever-present phenomenon in all of solid state physics. Phonons, quanta of heat, is the quasiparticule used to describe thermal motion in solids. Under normal conditions phonons are the dominant mechanism that govern transport and the largest contribution to entropy. I want to understand how phonons evolve in time, temperature, and how they behave when they interact strongly with each other or other quasiparticles.
The inherent disorder in thermal motions makes theoretical predictions challenging. I will present methodological developments in finite temperature first principles simulations, specifically targeting strongly anharmonic systems. The method employs model Hamiltonians that explicitly depend on temperature. I will present applications pertaining to thermal conductivity, inelastic neutron spectra and phase stabilities, reproducing non-trivial temperature dependencies.

The conserved signal recognition particle (SRP) system is essential for the biogenesis of integral membrane proteins (IMPs). The E. coli membrane associated SRP-receptor FtsY is a key player in the SRP system, although very little is known about its targeting and association with the membrane. Previous work done in our lab showed that FtsY targeting to the membrane is of a co-translational nature; during its translation, a specific domain emerges out of the ribosome and serves as the signal for membrane localization. This domain was characterized both functionally and structurally, but the manner by which this entire ribosome-nascent chain complex targets the membrane remains mostly unclear. In order to shed light on this mechanism, we have developed a co-translational and in-vivo site-specific crosslinking system. Using ribosome stalling-sequence and amber suppression, we are trying to identify direct co-translational protein-protein interactions involved in the membrane docking event of FtsY.