Past event

1st Grenoble cryoEM club meeting

28th of March 2024
IBS Seminar room, EPN Campus, Grenoble

14:00   Meeting introduction: Felix Weis, Isai Kandiah, Wojtek Galej

14:10   Short talk: Eymeline Pageot (IBS)

14:30   Short talk: Matthew Bowler (EMBL)

14:50   Short talk: Cecile Morlot (IBS)

15:10    Keynote talk: Christopher Russo, MRC LMB, Cambridge, UK

16:10    Closing remarks

16:15    Coffee and poster session

Keynote speaker

Christopher Russo, PhD

Born in Detroit Michigan, Chris attended the University of Notre Dame where he studied electrical engineering and philosophy. He then went on to graduate school at Harvard and MIT, where he studied physics and medicine under the supervision of Jene Golovchenko (Physics, Engineering) and Daniel Branton (Biology). During this time, he developed a new technique to create nanopores in graphene with atomic precision that combined ion bombardment with high energy electron irradiation.

He then moved to the MRC Laboratory of Molecular Biology in Cambridge UK to work on developing new methods for electron cryomicroscopy (cryo-EM). Chris has since started his own group at LMB, and continues to study the physical phenomena that limit resolution in cryo-EM and thus enable the development of new devices, instruments and methods to improve the imaging power of the electron microscope in biology.

Keynote talk

Realizing the potential of electron cryomicroscopy: democratizing structural biology at 100 keV and new technology to identify molecules in cells without labels

Electron cryomicroscopy (cryoEM) of biological specimens preserved by vitrification in water ice has made great strides in the last decade. The atomic structure of most biological macromolecules can, at least in principle, be determined by direct imaging using bright field phase contrast. Major technological advances – in electron imaging hardware, data analysis software, and cryogenic specimen preparation technology – continue at pace and contribute to the exponential growth in the number of atomic structures determined by cryoEM. I will discuss our own efforts to continue the growth and democratization of cryoEM with the development of a new 100 keV electron cryomicroscope that is purpose- built for uncostly structure determination. Given this and other advances, it is now likely, that within a few years we will have experimental structures for hundreds of thousands of unique protein and nucleic acid molecular complexes. But the answers to many important questions in biology would become obvious if we could identify these structures precisely inside cells with quantifiable error. In the context of an abundance of known structures, it is also appropriate to now consider the current state of electron cryomicroscopy for frozen specimens prepared directly from cells, and try to understand what technology can be brought to bear on this goal, both now and in the foreseeable future.

Short talks
Eymeline Pageot
(IBS Grenoble)
Integrative structural biology of cell extracts: an application to the structurally undercharacterized organism Physarum polycephalum

Integrative structural biology of cell extracts bridges the gap between the high resolution structural characterisation of highly purified, isolated biomolecules and in situ electron tomography. This booming technique combines mass spectrometry (MS)-based proteomics and cryo-electron microscopy (cryo-EM) of fractionated cell extracts to quantitatively and structurally characterise endogenous proteins and complexes. We chose to employ this method on Physarum polycephalum, which is absent from protein sequence and structure databases (Uniprot, PDB, EMDB) in order to mimic the challenges posed e.g. by emerging pathogens. We will show how structural biology can be applied when only raw genomic data is available, and discuss the difficulties faced to identify and annotate protein and complexes structures when no prior information is available.

Matthew Bowler
(EMBL Grenoble)
Architecture of the MKK6-p38α complex defines the basis of MAPK specificity and activation

The mitogen-activated protein kinase (MAPK) p38α is a central component of signaling in inflammation and the immune response and is, therefore, an important drug target. Little is known about the molecular mechanism of its activation by double phosphorylation from MAPK kinases (MAP2Ks), because of the challenge of trapping a transient and dynamic heterokinase complex. We applied a multidisciplinary approach to generate a structural model of p38α in complex with its MAP2K, MKK6, and to understand the activation mechanism. We demonstrate a dynamic, multistep phosphorylation mechanism, identify catalytically relevant interactions, and show that MAP2K-disordered amino termini determine pathway specificity.

Cecile Morlot
(IBS Grenoble)
Ultrastructure of macromolecular assemblies contributing to bacterial spore resistance revealed by cryo-FIB milling and cryo-electron tomography 

Bacterial spores owe their incredible resistance to molecular structures that protect them from external aggressions. Such resilience is an asset when spores are used for the benefit of humans (e.g. probiotics), or a problem for public health when it comes to spores of pathogenic bacteria. Among the determinants of spore resistance is an extracellular shell made of more than 80 different types of proteins (the coat). Using in situ cryo-electron microscopy methods in Bacillus subtilis, we have described the early stages of coat assembly into amorphous and structured layers, whose architecture relies on the deposition of a few morphogenetic proteins.