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Portrait Marcus Jahnel

The molecular world, where nothing ever stands still, poses some intriguing challenges to our understanding of living matter. How do molecules robustly self-organize into compartments, transmit signals or generate forces in the omnipresence of thermal fluctuations? How are decisions made reliably on that level? And how can tiny molecular changes lead to significant effects for an organism on different length and time scales?

Our team works at the intersection of molecular cell biology and polymer physics, and we are fascinated by the emergent molecular behavior of Life's building blocks. We see proteins and RNAs as multifaceted actors that readily adopt roles as information carriers, as structural materials, as complex fluids, as molecular thermometers, as choreographers, as timekeepers, soft machines, and sometimes all at once. This fascinating molecular universe offers a rich playground to expand both our understanding of physics and biology.

To investigate the dynamic nature of Life's molecules, we employ a captivating property of light: it can be used to exert and measure minute forces, forces so small that it allows us to study and manipulate individual molecular players with precision. In essence, we use the Physics of Light to study the Physics of Life.

Marcus Jahnel Research: Figure
Figure: Our lab uses high-resolution dual-trap optical tweezers (top left) to measure and exert forces on single molecules and molecular collections. For example, we are stretching biomolecular condensate droplets to learn more about their material properties (top right). Currently, we study the physics of polymer engines and explore the biology of protein-RNA liquids from various angles (bottom).

Future Projects and Goals

The ability to manipulate and study individual molecules and functional assemblies in vitro has revolutionized our understanding of the biology and physics of Life's molecules. However, many, many puzzles remain! Come and help us better understand:

  • Material properties of biomolecular condensates
    How to assess whether a given condensate behaves like a liquid, a gel, or a glass? Using our optical tweezers and microfluidics, we design new workflows to extract material parameters of complex protein-RNA fluids under changing conditions, with a particular interest on active processes.
  • RNA folding and misfolding in the presence of disordered proteins
    How do long regulatory RNAs fold in the context of RNA chaperones? We use delicate optical tweezer experiments to unfold a single regulatory RNA and study the effect of RNA-binding proteins undergoing phase transitions.
  • Fossil droplets and the evolution of biomolecular condensates
    When did proteins and RNAs start to condense, and how do the material properties of condensates vary among organisms? With a combination of bioinformatics and biophysical experiments, we explore how biomolecular condensates changed over time.
  • Active tethers of EEA1 & RAB5
    How do long coiled-coil proteins and small GTPases generate forces? We use optical tweezers, microfluidics, and polymer theory to analyze the dynamic aspects of this new molecular motor system.

Methodological and Technical Expertise

Our toolbox to tackle some molecular mysteries:

  • Measuring or applying minute forces using light alone (optical tweezers)
  • Performing delicate single-molecule experiments with proteins and nucleic acids
  • Combining image processing, data science (Python & R), and simulations (Julia)
  • Applying concepts from polymer and soft matter physics in back-of-the-envelope models


Since 2021
Joint Group Leader at the Cluster of Excellence Physics of Life and the BIOTEC, TU Dresden

Staff Scientist at TUD BIOTEC and MPI-CBG, Dresden

PostDoc at MPI-PKS & MPI-CBG, Dresden

PhD in Physics, MPI-CBG & TUD, Dresden

M.Sc. (by Research) in Physics, University of Manchester, UK

B.Sc. in Physics, University of Leipzig, Germany

Selected Publications

Murray DH*, Jahnel M*, Lauer J, Avellaneda MJ, Brouilly N, Cezanne A, Morales-Navarrete H, Perini ED, Ferguson C, Lupas AN, Kalaidzidis Y, Parton RG, Grill SW, Zerial M
An endosomal tether undergoes an entropic collapse to bring vesicles together.
Nature 537, 107–111 (2016)

Patel A, Lee HO, Jawerth L, Maharana S, Jahnel M, Hein MY, Stoynov S, Mahamid J, Saha S, Franzmann TM, Pozniakovski A, Poser I, Maghelli N, Royer LA, Weigert M, Myers EW, Grill S, Drechsel D, Hyman AA, Alberti S
A Liquid-to-Solid Phase Transition of the ALS Protein FUS Accelerated by Disease Mutation.
Cell, 162:5, 1066–1077 (2015)

Franzmann TM, Jahnel M, Pozniakovsky A, Mahamid J, Holehouse AS, Nüske E, Richter D, Baumeister W, Grill SW, Pappu RV, Hyman AA, Alberti S
Phase separation of a yeast prion protein promotes cellular fitness.
Science 359:6371 (2018)

Jahnel M*, Behrndt M*, Jannasch A, Schäffer E, Grill SW
Measuring the complete force field of an optical trap.
Optics Letters 36:7, 1260–1262 (2011)

Lisica A, Engel C*, Jahnel M*, Roldán É*, Galburt EA, Cramer P, Grill SW
Mechanisms of backtrack recovery by RNA polymerases I and II.
PNAS 113 (11) 2946–2951 (2016)

* equal contribution


Biotechnology Center of the TU Dresden (BIOTEC)
Tatzberg 47/49
01307 Dresden