The conformations populated during protein folding have been studied for decades; yet, their evolutionary importance remains largely unexplored. Ancestral sequence reconstruction allows access to proteins across evolutionary time, and new methods such as pulsed-labeling hydrogen exchange coupled with mass spectrometry allow determination of folding intermediate structures at near amino-acid resolution. Here, we combine these techniques to monitor the folding of the ribonuclease H family along the evolutionary lineages of T. thermophilus and E. coli RNase H. All homologs and ancestral proteins studied populate a similar folding intermediate despite being separated by billions of years of evolution. Even though this conformation is conserved, the pathway leading to it has diverged over evolutionary time, and rational mutations can alter this trajectory. Our results demonstrate that evolutionary processes can affect the energy landscape to preserve or alter specific features of a protein's folding pathway.
- Shion An Lim
- Eric Richard Bolin
- Susan Marqusee
- Shion An Lim
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Lewis E Kay, University of Toronto, Canada
- Received: May 14, 2018
- Accepted: September 9, 2018
- Accepted Manuscript published: September 11, 2018 (version 1)
© 2018, Lim et al.
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