CCEMMP Seminar Series

The CCeMMP are running a monthly research seminar series for interested researchers, research staff, students and enthusiasts. The seminar will be based mainly around cryo-electron microscopy of/and membrane proteins with a mixture of domestic and international speakers in this field. Speakers will be announced monthly with a calendar invitation with speaker and virtual details.

The seminar will be held at 10:00-11:00am AEDT/AEST on every second Tuesday of each month. If you would like to be invited to the seminars, please register to this event and the Centre Manager will send you calendar invitations.

 

Seminar dates for 2022

  • 14 June – Doctor Jianping Wu
  • 12 July – Doctor Natalie Zeytuni

The CCeMMP also run special seminars outside of the regular seminar series. See below for the presenters and registration details.

 
Special seminar dates for 2022

Past seminars

10 May 2022

Doctor Raphael Trenker

Postdoctoral Fellow

Natalia Jura Lab

Cardiovascular Research Institute

University of California San Francisco

Structures of the HER2-HER3-NRG1b receptor complex reveal a dynamic dimer interface induced

The Human Epidermal Growth Factor Receptor 3 (HER3) and its close homolog, the orphan receptor HER2, are single pass transmembrane receptor tyrosine kinases that form a pro-oncogenic signaling complex upon binding to the HER3 ligand neuregulin-1b (NRG1b). Until recently, there were no structural insights into the HER2/HER3 heterodimer owing to the difficulties in its reconstitution in vitro. We isolated near full-length HER2/HER3/NRG1b heterocomplex and obtained a 2.9 Å cryo-electron microscopy (cryo-EM) reconstruction of the extracellular domain module, which revealed a surprisingly dynamic dimerization interface. Based on additional structures of this heterocomplex in which HER2 harbors its most frequently observed oncogenic mutation, S310F, and of this complex bound to the therapeutic antibody trastuzumab, it will be discussed how oncogenic mutations and therapeutics appear to exploit the intrinsic dynamics of the HER2/HER3 heterodimer.

Structural characterization of conserved neutralizing epitopes on the SARS-CoV-2 spike glycoprotein

SARS-CoV-2 infection or vaccination produces neutralizing antibody responses that contribute to better clinical outcomes. The receptor binding domain (RBD) and the N-terminal domain (NTD) of the spike trimer (S) constitute major neutralizing targets for the antibody system. Here we describe structures of donor-derived broadly-neutralizing antibodies bound to RBD and NTD epitopes that are conserved across the major SARS-CoV-2 variants of concern. We conclude SARS-CoV-2 infection and/or Wuhan-Hu-1 mRNA vaccination produces a diverse collection of memory B cells that produce anti-spike antibodies, some of which can neutralize variants of concern and likely contributes to the relatively benign course of subsequent infections with SARS-CoV-2 variants including omicron.

5 April 2022

Assistant Professor Christopher Barnes

Biology and ChEM-H Institute Scholar

Stanford University

8 March 2022

Assistant Professor Oliver Clarke

Physiology and Cellular Biophysics 

Anesthesiology & the Irving Institute for Clinical and Translational Research 

Columbia University

Architecture of the erythrocyte ankyrin-1 complex elucidated by Cryo-EM
The stability and shape of the erythrocyte membrane is provided by the ankyrin-1 complex, but how it tethers the spectrin-actin cytoskeleton to the lipid bilayer and the nature of its association with the band 3 anion exchanger and the Rhesus glycoproteins remains unknown. Here we present structures of ankyrin-1 complexes purified from human erythrocytes, and sub-tomogram averages of the same complexes from native membrane vesicles. We reveal the architecture of a core complex of ankyrin-1, the Rhesus proteins RhAG and RhCE, the band 3 anion exchanger, protein 4.2 and glycophorin A. The distinct T-shaped conformation of membrane-bound ankyrin-1 facilitates recognition of RhCE and unexpectedly, the water channel aquaporin-1. Together, our results uncover the molecular details of ankyrin-1 association with the erythrocyte membrane, and illustrate the mechanism of ankyrin-mediated membrane protein clustering.
Discovering how pore forming proteins evolve different assembly and targeting mechanisms

Pore forming proteins are proteins that can literally punch holes (pores) into target cell membranes. There are over 30 different types of pore forming proteins that have evolved independently but one of the most fascinating is the MACPF/CDC superfamily. The MACPF/CDC proteins can oligomerise into a ring-shaped transmembrane beta-barrel pore capable of either direct cell lysis or the passive transport other large protein toxins. Members of the MACPF/CDC superfamily are found in all kingdoms of life with a range of functions including as immune effectors, pathogenicity factors, parasite egress, fungal defence and marine toxins. Whilst current structural biology research on the MACPF/CDC family suggest there is a common domain and a common pore structure for the family, there is a wide variation in the assembly pathways observed. Recent research using combinations of structure and single molecule imaging methods explains how and why different members have evolved different assembly pathways to suit their evolved function.

15 February 2022

Associate Professor Michelle Dunstone

Department of Biochemistry and Molecular Biology

Biomedical Discovery Institute

Monash University

 

14 December 2021

Doctor Doreen Matthies

Earl Stadtman tenure track investigator

Head, Unit on Structural Biology

Division of Basic and Translational Biophysics

Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

Cryo-EM of membrane proteins:
What have we learned in the last decades and what are the challenges?

In the last decade the field of Structural Biology has made great advances in using electron microscopy to solve structures of protein complexes including membrane proteins to high resolution. Best practices of how to use Single Particle Cryo-EM and more importantly how to optimize a membrane protein sample such as an ion channel or a transporter will be discussed. Most membrane protein structures are currently resolved in a detergent micelle, but cryo-EM also makes it possible to look at membrane protein complexes in a lipid bilayer, such as synthetic or native lipid nanodiscs, liposomes, or even inside cells now. A brief introduction to each of these techniques will be discussed with examples of the conformational landscape of magnesium channel CorA, voltage-gated potassium channel Kv1.2-2.1, a human excitatory amino acid transporter and more.

Using cryo-EM to interrogate the structure and dynamics of GPCRs

Cryo-electron microscopy (cryo-EM) continues to grow as a powerful method for structural studies of biomolecules and their complexes. Nowadays, it can routinely determine molecular structures with resolutions in the 2.5 – 3.5 Å range. Such results are adequate for modelling of the protein but lack fidelity for confident localization of water molecules and hydrogen atoms. Unambiguous elucidation of the biochemistry behind protein function and pharmacology of drugs would require atomic resolution structures, at levels below 1.5 Å. Last year, several groups worldwide demonstrated atomic resolution cryo-EM with a test sample comprising the “easy” soluble protein apoferritin. This was an important technological milestone showcasing the best-case-scenario capabilities of cryo-EM. However, membrane proteins, and other real-world samples, impose numerous experimental challenges, such as small size, heterogeneity, flexibility, preferential orientation, etc. 

9 November 2021

Professor Radostin Danev

Advanced Structural Studies

Graduate School of Medicine, The University of Tokyo

12 October 2021

Professor Patrick Sexton

Director, ARC Centre for Cryo-electron Microscopy of Membrane Proteins; 

Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University

Using cryo-EM to interrogate the structure and dynamics of GPCRs

G protein-coupled receptors (GPCRs) are the largest superfamily of cell surface receptor proteins and a major target class for drug development. GPCRs are inherently flexible proteins that have evolved to allosterically communicate external signals to modulation of cellular function through recruitment and activation of transducer proteins, particularly G proteins. Technological evolution in cryo-EM combined with continuing advances in biochemical approaches for the stabilisation of active-state complexes of GPCRs with different transducer proteins is now enabling structural interrogation of receptor activation and transducer engagement. Moreover, cryo-EM can access conformational ensembles of GPCR complexes that are present during vitrification, which can provide a window into the dynamics of these complexes.