Date of Award
MS in Biology
Otopetrins (OTOP) represent a new family of eukaryotic proton channels that do not share structural similarities with other renowned ion channels. Otop1 was initially known for its involvement in vestibular function and its significance for otoconia formation before it was established as a bona fide sour taste receptor. The cryo-EM structures for several Otop channels have been determined and demonstrated Otop1 as a homodimer comprised of two subunits. Each subunit constitutes twelve transmembrane helices that can be further partitioned into two structurally similar six transmembrane domains designated as the N and C domains. Molecular dynamic simulations have also previously shown how lipid molecules occupy the center conducting pore and impede the permeation of protons, suggesting that it is likely not involved in proton transmission. As a result, three putative pores for proton conduction that have been proposed are within the N domain, the C domain, and the intrasubunit interface. Our study focuses on determining whether Otop1 can function as a monomer and if it possesses the same proton conducting pores as its dimeric architecture. By destabilizing the hydrophobic interactions occurring at the interface between two monomers, we generate monomeric mutants that prove that dimer formation is not required, and we introduce pore mutations in the N and C domains to verify that these monomers have the same proton permeation pathways as the dimer. This study enhances our comprehension of the Otop1 structure as it indicates that dimerization is not necessary. However, why Otop1 needs to form a dimer if the monomer is functional remains elusive.
Ulloa, Gabriella Abigail, "HUMAN OTOP1 PROTON CHANNEL CAN FUNCTION AS A MONOMER" (2022). Theses and Dissertations. 468.
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