James Saenz, Ph.D.

Education: Massachusetts Institute of Technology, Ph.D., Chemical Oceanography
Institution: Max-Planck-Institut fuer Molekulare Zellbiologie u. Genetik (laboratory of Tony Hyman)

SCOL Project: The Emergence and Evolution of Molecular Order in the Cell Membrane

One of the most interesting and elusive problems in science has been to understand how life emerged on earth. This is intricately linked to the question: How did the first cells arise? Modern life employs a complex and highly interconnected chemical system to assemble its parts and replicate. However, life did not start with these advanced biochemical tools and would have relied on simple systems that 1) could self assemble from preexisting molecules available on early Earth and 2) segregate biomolecules from the environment by some means of compartmentalization. Encapsulation by lipid membranes is one mechanism to compartmentalize primitive biomolecules.

In the scope of this proposal I want to ask: what were the early Earth membranes like? Membranes are thought to have emerged from the self-assembly of primitive lipids that were present on early Earth. The properties of early membranes would have been dependent on the structure of these primitive lipids. Over time, evolution would then have selected more specialized membrane compositions ultimately leading to the first cellular membranes. In this context, the interactions between membranes and early biomolecules (e.g. RNA) may even have served as a primitive form of heredity before a formalized genetic code emerged.

I will examine the properties of membranes that could have emerged from potential early Earth lipids. In particular I will test how aromatic hydocarbons that are thought to have been present on early Earth can modulate the thermodynamic order of membrane lipids. I will approach this through a comprehensive range of classical and modern biophysical tools in model membrane systems aimed at mimicking the complexity of primitive membranes.

By understanding the potential distribution of properties of primitive membranes, I aim to excavate the fundamental principles that allowed life to emerge, bringing us closer to understanding how modern membranes function and how to engineer functional membranes from the bottom up.