Transmembrane Transport and the Last Universal Common Ancestor

Abstract

This thesis reviews literature on the importance of membrane transport to the development of the last universal common ancestor (LUCA). Although no one is certain what the exact amphiphilic composition of the earliest membranes was, environmental and energetic constraints on the complexity of membrane proteins would force the first membranes to be leaky in comparison to their modern counterparts. Yet, even with increased permeability to ions, LUCA was likely able to create useful membrane folds to gain control over its interactions with the environment. Using studies from the LUCApedia database, 35 peptide folds associated with membrane transport – 3 of which were alpha helices – were identified. Lastly, the relationship between membrane transport and energy production was discussed, centered around alkaline vent theories on LUCA’s emergence as an autotroph. The evolution of the protein constituents of chemiosmosis and electron transport was described in regards to protein folds.