Matthew T Swulius
California Institute of Technology, USA
Title: Breathing life into static images: Combining electron cryotomography and coarse-grained simulations to explore mechanisms of eukaryotic cell division machinery in vivo
Biography
Biography: Matthew T Swulius
Abstract
While electron cryotomography (ECT) is a powerful technique for imaging unique biological structures to molecular resolution, some protein machinery is complex and highly dynamic, making static images difficult to interpret on their own. In such cases, coarse-grained simulations can be employed in order to interpret and test the mechanistic implications of such experimental data. Here we use a combination of ECT and simulation to study the structure and contractile mechanism of the actomyosin ring (AMR) in fission yeast. Because fission yeast are beyond the thickness amenable to cryoEM, we used cryo-focused ion beam milling and cryosectioning to gain access to natively preserved AMRs. ECT revealed bundles of actin filaments running parallel to one another that were “saddling” the leading edge of the septum, and no direct contact between actin and the membrane was observed, refuting the notion that F-actin is connected to the membrane at cytokineteic nodes. After exploring a variety of actomyosin configurations by 3D coarse-grained simulation, we propose a model that best agrees with our and other published experimental data.
