2023/02/01 Tamir Bendory

Tamir Bendory

Electrical Engineering Assistant Professor at Tel Aviv University

Date and time: February 1st, 2023
Wednesday, at 8am PST / 11am EST / 4pm GMT / 5pm CET / midnight China

For the zoom and gather.town links, please join the One World Cryo-EM mailing list.

Recovering small molecular structures using Cryo-EM

Any current Cryo-EM algorithmic pipeline entails recovering the 3-D structure after particle picking. However, the signal-to-noise ratio of the data, and thus the reliability of particle picking, drops with the molecular mass of the specimens. Accordingly, it is commonly believed that Cryo-EM cannot be used to map molecules with a molecular mass below a certain threshold. Challenging this misconception, I will argue that finding the particle picking is not a prerequisite for structure determination and thus small molecules are, at least in principle, within reach of Cryo-EM. Then, I will introduce two computational frameworks to bypass particle picking and show numerical results.

2023/03/01 Petar Petrov

Petar Petrov

Postdoctoral Scholar at University of California, Berkeley

Date and time: March 1st, 2023
Wednesday, at 8am PST / 11am EST / 4pm GMT / 5pm CET / midnight China

For the zoom and gather.town links, please join the One World Cryo-EM mailing list.

Laser phase-contrast Cryo-EM and associated computational opportunities

A phase plate can provide optimum image contrast for weak-phase objects in transmission  electron microscopy, but approaches toward realizing a phase plate have suffered from  instabilities. We have developed a phase plate that is based on coherently phase-shifting the  electron wave function by a laser beam, which is built up to a record-high intensity of ~400  GW/cm^2 by resonance in a Fabry-Perot cavity. We have demonstrated contrast enhancement  with the laser phase plate (LPP) and shown the long-term stability of the device, as well as  generated a high-resolution map of 20S proteasome particles using a standard single-particle  cryo-electron microscopy (Cryo-EM) workflow. 

This talk will focus on our recent work to move beyond proof-of-concept, as well as the  computational opportunities that lie ahead. To demonstrate the benefits of the LPP to Cryo-EM  as well as cryo-electron tomography, we will soon begin working with a state-of-the-art  microscope equipped with a spherical aberration corrector, gun monochromator, and post column energy filter. We will explore improvements to the phase plate design and pursue new  strategies for image acquisition and processing, such as high-resolution two-dimensional  template matching.