A spatiotemporal model of endosomal architecture and function

Endosomes are the organelles where trafficking, signalling, homeostasis and autophagy meet. Their aberrant function is linked to many pathophysiological states and they are the major site of pathogen entry into cells. Cellular TM- protein logistics require that cargo is moved within the endosomal system and dispatched to other organelles under tight spatial and temporal control. This requires that characteristics of endosomal limiting membranes from which membrane-bound carriers leave, must be coupled to the endosomal luminal environment as endosomes mature towards low-pH/degradative compartments. To understand how this is achieved, we need to understand the molecular mechanisms of endosomal machineries and how they are regulated and integrated to generate this finely controlled dynamic system. We will integrate top-down and bottom-up structural/functional approaches to view endosomes through different magnification lenses from organelle morphology to high-resolution mechanistic studies of proteins that control endosomal physiology or drive transport carrier formation. Intermediate resolutions, critical to understanding the architecture/organisation and function of machineries/assemblies on an endosome’s surface, will be studied using cryo- electron tomography. Structural data will be combined with biochemical and phase-separation studies to contextulaise and drive ‘in-cell’ studies resulting in a comprehensive, multi-resolution, 4-dimensional structural/functional model of an endosome’s function and architecture throughout its life.