Protein-protein interactions involving intrinsically disordered proteins are important for cellular function and common in all organisms. However, it is not clear how such interactions emerge and evolve on a molecular level. We performed phylogenetic reconstruction, resurrection and biophysical characterization of two interacting disordered protein domains, CID and NCBD. CID appeared after the divergence of protostomes and deuterostomes 450-600 million years ago, while NCBD was present in the protostome/deuterostome ancestor. The most ancient CID/NCBD formed a relatively weak complex (Kd~5 μM). At the time of the first vertebrate-specific whole genome duplication the affinity had increased (Kd~200 nM) and was maintained in further speciation. Experiments together with molecular modeling using NMR chemical shifts suggest that new interactions involving intrinsically disordered proteins may evolve via a low affinity complex which is optimized by modulating direct interactions as well as dynamics, while tolerating several potentially disruptive mutations.
- Per Jemth
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Jeffery W Kelly, The Scripps Research Institute, United States
© 2017, Hultqvist et al.
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