Buzz Baum

My team is interested in the generation of biological form or “morphogenesis”. We study events at the cellular scale because the cell is the unit of life. Much of the lab’s work focuses on cell division – the process by which becomes two. This is one of the most remarkable and fundamental features of all life on earth. During division, within a timeframe of a few minutes, all the component parts of a cell must be moved apart and partitioned into two daughter cells. Thus, division must be done with precision to ensure the propagation of a lineage, and errors in division are frequently associated with diseases like cancer in humans and can cause cell death.

Rapid changes in cell shape and organisation, including those that accompany division, are brought about by a network of dynamic polymers – the cytoskeleton. These filaments convert chemical energy into force as they grow and shrink. Strikingly, recent evolutionary studies have shown that the key cytoskeletal elements used to drive division and other shape changes in our cells are ancient proteins, which we inherited from our archaeal ancestors during the process of eukaryogenesis.

Taking advantage of this discovery, in exploring the fundamentals of cell division, my lab is looking at the similarities and differences in the way archaea and eukaryotic cells divide. Using Sulfolobus as a genetically tractable model in which to study archaeal cell biology, we aim to identify conserved processes, core principles, and to determine how division has changed during the transition from archaea to eukaryotes. This work has led us to study the structure and function of ESCRT-III filaments, which catalyse the final step in division in both Sulfolobus and in human cells.

Working with archaea also means grappling with some the weirder features of these extremophiles. Sulfolobus cells, which were originally isolated from hot acidic pools in Yellowstone National Park, grow at 75°C and have membranes that are largely composed of monolayer lipids. Thus, understanding their cell biology requires re-thinking some of our most basic assumptions (bilayers membranes) and the development of new research tools and methods (high-temperature live cell imaging).

Taking this evolutionary cell biology approach further, in the coming years we will also be turning our attention to the Asgard archaea. These are our closest living archaeal relatives. Asgard archaea have extraordinary shapes and, in some cases, partner with cells of other species to grow. They are therefore ideal models in which to study the evolution of cell division, cell shape control, and symbiosis.

We expect this work, much of which is done with collaborators at the LMB, in the UK and overseas, to shed light on the process by which eukaryotic cells emerged from the symbiosis of an Asgard archaeal cell with an alpha-proteobacterial partner that gave rise to the mitochondria. In doing so, we will put the “inside-out model” for the origin of the eukaryote cell to the test. For the moment, the evolution of eukaryotes remains one of the greatest mysteries in the history of life on earth. We hope to help change this.