September 19, 2023

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Speaker: Valerie De Anda, Provost’s Early Career Fellow and a Research Associate, Marine Science Institute, The University of Texas at Austin

Host: Brett Baker

Title: From Eukaryogenesis to Membrane Origins: using microbial metabolism as fossil record of early life

Abstract: The origin of eukaryotes (eukaryogenesis) and the lipid composition of cellular membranes (lipid divide) have represented the most contentious problems in biology for decades. Recent findings, such as the discovery of Asgard archaea, have provided new clues on the emergence of complex life. Asgard archaea are now considered the closest prokaryotic relatives of eukaryotes, yet little is known about the Asgard ancestor involved in the eukaryogenesis event (some 2 Gya). By using microbial metabolism as a fossil record of early life, we inferred the metabolic capabilities of the Asgard ancestor that gave rise to eukaryotes, including humans. Furthermore, we unravel another intriguing puzzle: the “lipid divide” which centers on the distinct lipid membrane compositions that separate bacteria and eukaryotes from archaea and how modern eukaryotes acquired their unique membrane-lipid composition. Drawing from the geological record we searched for genes that could explain the presence of steranes (fossilized lipids that are derived from sterols, a class of lipids produced by all major groups of eukaryotes). Until now, no archaea has been found to produce sterols in their membranes. By bridging different disciplines we identified for the first time sterol-like biosynthesis genes in Asgard archaea and verified their functionality through in vitro protein expression and lipid analyses. This is the first evidence of an experimentally diterpenoid cyclase in any archaea and the first to be described in Asgard representatives, providing new insights into the origin of membranes in complex life. Join us for a journey that transcends disciplinary boundaries and provides key insights into the prokaryote-to-eukaryote transition and the emergence of complex life on Earth.

Biography: Valerie De Anda is a 2023 Provost’s Early Career Fellow and a Research Associate in the Baker Marine Microbial Ecology laboratory at UT Austin. She uses microbial metabolism to understand the past, present, and future outcomes of life on Earth. Her research focuses on unraveling the chemical and metabolic principles of life across ecological and evolutionary scales to develop an understanding of microbial properties and their implication in a changing environment. She earned her BSc in Biology and her PhD in Microbial Ecology at the National Autonomous University of Mexico, both with summa cum laude. Her research has been published in high impact journals, including Nature, Nature Microbiology, and Nature Communications. Valerie has been invited to present her work in 10 countries at international conferences and universities and obtained several international awards. As a Mexican, first-generation female scientist, Valerie is committed to enhancing the representation and opportunities for women in science and other underrepresented groups. She believes that making science more diverse starts by awakening and empowering children and students that just need to see themselves reflected in real-life scientists from diverse backgrounds.