Non-conservation of folding rates in the thioredoxin family reveals degradation of ancestral unassisted-folding Gámiz Arco, María Gloria Risso, Valeria Alejandra Candel, Adela M. Inglés Prieto, Álvaro Romero Romero, María Luisa Gaucher, Eric A. Gavira Gallardo, José Antonio Ibarra Molero, Beatriz Sánchez Ruiz, José Manuel Evolution involves not only adaptation, but also the degradation of superfluous features. Many examples of degradation at the morphological level are known (vestigial organs, for instance). However, the impact of degradation on molecular evolution has been rarely addressed. Thioredoxins serve as general oxidoreductases in all cells. Here, we report extensive mutational analyses on the folding of modern and resurrected ancestral bacterial thioredoxins. Contrary to claims from recent literature, in vitro folding rates in the thioredoxin family are not evolutionarily conserved, but span at least a ∼100-fold range. Furthermore, modern thioredoxin folding is often substantially slower than ancestral thioredoxin folding. Unassisted folding, as probed in vitro, thus emerges as an ancestral vestigial feature that underwent degradation, plausibly upon the evolutionary emergence of efficient cellular folding assistance. More generally, our results provide evidence that degradation of ancestral features shapes, not only morphological evolution, but also the evolution of individual proteins. 2020-02-13T12:22:00Z 2020-02-13T12:22:00Z 2019 journal article Gamiz-Arco, G., Risso, V. A., Candel, A. M., Inglés-Prieto, A., Romero-Romero, M. L., Gaucher, E. A., ... & Sanchez-Ruiz, J. M. (2019). Non-conservation of folding rates in the thioredoxin family reveals degradation of ancestral unassisted-folding. Biochemical Journal, 476(23), 3631-3647. http://hdl.handle.net/10481/59651 10.1042/BCJ20190739 eng http://creativecommons.org/licenses/by-nc-nd/3.0/es/ open access Atribución-NoComercial-SinDerivadas 3.0 España Portland Press