Date & Location: February 15, 2021, at 4p; Virtual visit
Subject: Exploring molecular landscapes inside photosynthetic organisms with cryo-electron tomography
Host: Peter Lundquist
About the Speaker
University: Helmholtz Zentrum München
Research Interests: Cells accomplish the biochemical reactions of life by concentrating their proteins into a variety of subcellular compartments called organelles. The Engel group explores the relationship between the form of the organelle and the function of its resident macromolecules. How does organelle architecture direct molecular function, and reciprocally, how do macromolecules sculpt and shape organelles?
To investigate these questions, the group uses cryo-electron tomography (cryo-ET) to directly visualize macromolecules “in situ”, within the native cellular environment. First, they rapidly freeze the cells in non-crystalline vitreous ice, preserving them in a state of suspended animation. Next, they use a focused ion beam to thin the cells, followed by cryo-ET to acquire 3D images (called tomograms) of the native cellular interior with molecular resolution. These tomograms enable researchers to solve molecular structures directly within the cell, at sufficient resolution to distinguish different conformational states and interaction partners. The researchers then map these structures back into the cellular volume with nanometer precision, allowing them to analyze molecular organization within the cell at the scale of single molecules.
Many of the lab's studies use the unicellular green alga Chlamydomonas reinhardtii, which has intricate and reproducible organelle architecture as well as superb cryo-EM imaging properties. In addition, the group explores a variety of cellular environments, including mammalian cells, yeast, several species of marine algae, and the ameoboflagellate Naegleria gruberi. The Engel group is especially fond of photosynthetic organisms, as they seek to understand how the light-harvesting and CO2-fixing compartments of the chloroplast are affected by environmental stress and climate change.