Measuring the speed of signal propagation in a deadly protein complex
How fast do signals run through proteins? In which time dimensions do proteins “sense” binding or structural alterations?
In two studies, we investigated the protein MCL-1, one of the key players in the programmed cell death, with a major role in numerous cancer types.
We found out that the destabilization of its natural binding partners, the BH3 domains, triggers a cascade of rearrangements in the protein complex. The signal propagation happens in the nano- to microsecond regime.
Furthermore, we could connect MCL-1's promiscuity for certain BH3 domains with these dynamic processes.
These new insights in the speed of molecular information transfer could deliver new viewpoints how to manipulate oncologically relevant MCL-1 protein complexes and to understand the nature of protein-protein interactions.
Signal propagation within the MCL-1/BIM protein complex.
Philipp J. Heckmeier, Jeannette Ruf, David Buhrke, Brankica G. Janković., Peter Hamm.
Journal of Molecular Biology: 167499 (2022). https://doi.org/10.1016/j.jmb.2022.167499
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MCL-1 promiscuity and the structural resilience of its binding partners.
Philipp J. Heckmeier, Jeannette Ruf, Brankica G. Janković., Peter Hamm.
J. Chem. Phys. 158, 095101 (2023). https://doi.org/10.1063/5.0137239
A new way to characterize small protein oligomers
The characterization of protein stoichiometry plays a fundamental role to understand the function of a protein, Does my protein of choice form a dimer, trimer, tetramer ... or does it stay monomeric?
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In this publication, we present an elegant way to determine the oligomerization state of small proteins with fluorescence anisotropy.
We could show that without highly-sophisticated equipment, we could differentiate between oligomers only recording the polarization of light emitted by our samples. For further information, click here.
Determining the Stoichiometry of Small Protein Oligomers using Steady State Fluorescence Anisotropy.
Philipp J. Heckmeier, Ganesh Agam, Mark G. Teese, Maria Hoyer, Ralf Stehle, Don C. Lamb, Dieter Langosch
Biophysical Journal, Volume 119, (2020); https://doi.org/10.1016/j.bpj.2020.05.025
Like a burned-out light bulb: unseen findings on green fluorescent protein
Green fluorescent protein (GFP) and other related fluorescent proteins are powerful reporter proteins in cell biology. In this study, we show that the irradiation of GFP with blue visible light is paralleled not only by irrversible photobleaching, but also by successive backbone fragmentation of the protein.
In mass spectrometric analysis, we demonstrate that the fragmentation site is directly at the fluorophore, between residue positions 65 and 66. This effect has never been shown before and may change the view on GFP as a reporter in molecular biological application.
Site-Specific Fragmentation of Green Fluorescent Protein Induced by Blue Light.
Philipp J. Heckmeier and Dieter Langosch
Biochemistry, July 27 2021; https://doi.org/10.1021/acs.biochem.1c00248
Further recent studies:
In this methodological paper, we present a stop-flow sample delivery system for transient spectroscopy, using two pulsing micro-valves. My idea to extent the flow cycle with elements to stop the flow helped to develop a new and extremely sample efficient set up for spectroscopic application.
A stop-flow sample delivery system for transient spectroscopy.
David Buhrke, Jeannette Ruf, Philipp J. Heckmeier, and Peter Hamm. Review of Scientific Instruments 92, 123001 (2021); doi: https://doi.org/10.1063/5.0068227
Cyanobacteriochromes are photoreceptive proteins. For this study, I could support our team at the Hamm Lab (University of Zurich) with generating the photosensory domain of the protein CBCR Slr1393 (see picture on the right), containing phycocyanobilin (PCB). The molecule was further investigated via transient IR-spectroscopy.
Nanosecond protein dynamics in a red/green cyano-bacteriochrome revealed by transient IR spectroscopy.
David Buhrke, Kerstin T. Oppelt, Philipp J. Heckmeier, Ricardo Fernández-Terán,
and Peter Hamm. J. Chem. Phys. 153, 000000 (2020);
doi: https://doi.org/10.1063/5.0033107