Constraints on the evolution of toxin-resistant Na,K-ATPases have limited dependence on sequence divergence

Authors

Shabnam Mohammadi, University of Nebraska-Lincoln, Universität Hamburg
Santiago Herrera-Álvarez, Universidad de los Andes, University of Chicago
Lu Yang, Princeton University
María del Pilar Rodrı´guez-Ordoñez, Universidad de los Andes
Karen Zhang, Princeton University
Jay F. Storz, University of Nebraska-LincolnFollow
Susanne Dobler, Universität Hamburg
Andrew J. Crawford, Universidad de los Andes
Peter Andolfatto, Columbia University

Document Type

Article

Date of this Version

8-16-2022

Citation

Mohammadi S, Herrera-Álvarez S, Yang L, Rodríguez-Ordoñez MdP, Zhang K, Storz JF, et al. (2022) Constraints on the evolution of toxinresistant Na,K-ATPases have limited dependence on sequence divergence. PLoS Genet 18(8): e1010323. https://doi.org/10.1371/journal. pgen.1010323

Comments

open access

Abstract

A growing body of theoretical and experimental evidence suggests that intramolecular epistasis is a major determinant of rates and patterns of protein evolution and imposes a substantial constraint on the evolution of novel protein functions. Here, we examine the role of intramolecular epistasis in the recurrent evolution of resistance to cardiotonic steroids (CTS) across tetrapods, which occurs via specific amino acid substitutions to the α-subunit family of Na,K-ATPases (ATP1A). After identifying a series of recurrent substitutions at two key sites of ATP1A that are predicted to confer CTS resistance in diverse tetrapods, we then performed protein engineering experiments to test the functional consequences of introducing these substitutions onto divergent species backgrounds. In line with previous results, we find that substitutions at these sites can have substantial background-dependent effects on CTS resistance. Globally, however, these substitutions also have pleiotropic effects that are consistent with additive rather than background-dependent effects. Moreover, the magnitude of a substitution’s effect on activity does not depend on the overall extent of ATP1A sequence divergence between species. Our results suggest that epistatic constraints on the evolution of CTS-resistant forms of Na,K-ATPase likely depend on a small number of sites, with little dependence on overall levels of protein divergence. We propose that dependence on a limited number sites may account for the observation of convergent CTS resistance substitutions observed among taxa with highly divergent Na,K-ATPases (See S1 Text for Spanish translation).