Tübingen biochemists use a super-microscope to watch Bax proteins start apoptosis
Damaged cells can commit suicide by a process of apoptosis, or programmed cell death. If this mechanism fails to work properly, the cell can become cancerous. Tübingen researchers in a team headed by professor Ana García-Sáez of the Interfaculty Institute of Biochemistry are helping to explain important steps in the process of apoptosis.
They know from previous studies that apoptosis begins with the activation of what are known as Bax proteins. If a cell is under stress, Bax proteins deposit on the surface of mitochondria in symmetrical pairs. The researchers then observed that the otherwise impermeable shell of the mitochondria becomes permeable – letting through cytochrome c.
Once that happens, the process of cellular death cannot be reversed. But what happened in between was a mystery which for a long time puzzled apoptosis researchers. Now Ana García-Sáez and her team have been able to use a supermicroscope to watch how Bax proteins form pores in the mitochondrial shell, making it permeable. Their study is published in The EMBO Journal.
In healthy cells Bax is present as a soluble, single protein, which moves back and forth between the cytoplasm and the surface of mitochondria. When stress signals set in, Bax proteins accumulate on mitochondria. Scientists had suspected that Bax pairs linked up to form pores, opening the outer shell of the mitochondria for certain substances. But until now, they had not been able to observe if Bax structures could form these pores on the mitochondria. For this reason, the doubt had been cast on the theory.
In collaboration with Jonas Ries at EMBL, Ana García-Sáez and her team used a super-resolution microscope that is able to make out individual molecules. This gave them images showing how Bax proteins gathered on mitochondria of cells under stress in cell-death mode.
The Bax structures they found were of differing shapes and sizes, but could not have been created by chance. They were in the shape of closed rings, incomplete rings, arcs like a sickle moon, and in lines. The formation of these structures of Bax correlated with the mitochondrial shell becoming permeable. This confirms the researchers’ hypothesis - thereby filling a crucial gap in our knowledge of the processes involved in apoptosis.
Raquel Salvador-Gallego, Markus Mund, Katia Cosentino, Jale Schneider, Joseph Unsay, Ulrich Schraermeyer, Johann Engelhardt, Jonas Ries and Ana J García-Sáez: Bax assembly into rings and arcs in apoptotic mitochondria is linked to membrane pores. The EMBO Journal, DOI 10.15252/embj.2015933841
Professor Ana García-Sáez
University of Tübingen
Interfaculty Institute of Biochemistry
Phone +49 7071 29-73318
Dr. Karl Guido Rijkhoek | idw - Informationsdienst Wissenschaft
The birth of a new protein
20.10.2017 | University of Arizona
Building New Moss Factories
20.10.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research