Septins (the fourth component of the cytoskeleton) - How to Assemble a Molecular Jigsaw

Abstract
Septins represent a fourth (somewhat neglected) component of the cytoskeleton whose involvement in essential intracellular events involving membrane remodeling and barrier formation has become increasingly apparent over recent years. Septins assemble into heteropolimeric filaments based on palindromic oligomers which polymerize end-to-end. For over a decade we have been attempting to understand the rules of assembly which guarantee how each individual subunit assumes its rightful position along the filament and how these subsequently unite into higher order structures which associate with membranes. By accumulating a large number of crystal and cryo-EM structures several features are beginning to emerge. In this talk, Richard will describe what has been learnt concerning the correct assembly of the inter-subunit interfaces and their unexpected dynamics, the metastable properties of the C-terminal coiled coils and the importance of a polybasic region necessary for forming electrostatic interactions with membranes. This is providing a more coherent picture of septin function and dysfunction, such as occurs in the case of off-target cleavage of septin 2 by the Zika NS2B3 protease.

Speaker
Prof Richard Charles Garratt has been on the academic staff of the São Carlos Institute of Physics at the University of São Paulo since 1992. After completing a PhD in crystallography at the University of London, he moved to the University of São Paulo, where he was instrumental in establishing the first protein crystallography laboratory in Brazil and possibly Latin America. His interests span many aspects of structural biology but principally the use of protein crystallography and homology modeling in the understanding of a wide range of biological phenomena at the molecular level.