Online Friday Seminar – Using electron cryotomography to visualise cell ultrastructure

Our next Friday Seminar speaker is Professor Grant Jensen from the Brigham Young University and California Institute of Technology.

The Friday Seminar series will be run on a virtual platform for the foreseeable future.

Email jic.fridayseminars@jic.ac.uk to request access to the recording.

Abstract

In the last ten years electron cryotomography (cryo-ET) has made it possible to visualise large macromolecular assemblies inside intact cells in a near-native, “frozen-hydrated” state in 3-D to a few nanometers resolution.

Increasingly, atomic models of individual proteins and smaller complexes obtained by X-ray crystallography, NMR spectroscopy, or other methods can be fit into cryotomograms to reveal how the various pieces work together inside cells.

To illustrate these points, Professor Jensen will present examples of current results from our recent work on the HIV-restriction protein Trim5α and the unfolded protein response sensor IRE1α, both of which form polymers inside cells.

He will also show how cryo-ET can be used to reveal the ultrastructures of bacteria, including pathogens.

Professor Grant Jensen biography

Grant Jensen is a Professor of Biochemistry and Dean of the College of Physical and Mathematical Sciences at Brigham Young University (BYU) in Provo, Utah.

He earned his doctorate working on electron microscopy of RNA polymerase and other protein complexes with Dr Roger Kornberg (who later won the Nobel prize for structural studies of transcription) at Stanford University.

Next Grant continued his work in protein electron microscopy as a Damon Runyon-Walter Winchell post-doctoral fellow under the supervision of Dr. Kenneth Downing at the Lawrence Berkeley National Lab. There his interests expanded to include electron tomography of whole cells.

Grant began his independent career at the California Institute of Technology (Caltech) in 2002. At Caltech his research has focused on three main areas: the ultrastructure of small cells, the structural biology of HIV, and the further development of cryo-EM technology. Together with his colleagues he has now published nearly 200 papers in these areas.

His lab has developed a searchable tomography database and populated it with ~50 thousand cryotomograms of over 100 different viral and microbial samples.

Among his most prominent discoveries has been the structure and function of the bacterial type VI secretion system, a “poison-tipped spring-loaded molecular dagger,” and the architecture of the type IV pilus responsible for cell motility.

All this work is now summarised in an electronic textbook, the Atlas of Bacterial and Archaeal Cell Structure.

Meanwhile Grant’s teaching has centered on biophysical methods, including the creation of the popular online course Getting started in Cryo-EM.

In 2020 Grant moved to BYU to become Dean of their College of Physical and Mathematical Sciences.

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