Abstract
The transcription factor c-Myb promotes the proliferation of hematopoietic cells by interacting with the KIX domain of CREB-binding protein; however, its aberrant expression causes leukemia. Therefore, inhibitors of the c-Myb–KIX interaction are potentially useful as antitumor drugs. Since the intrinsically disordered transactivation domain (TAD) of c-Myb binds KIX via a conformational selection mechanism where helix formation precedes binding, stabilizing the helical structure of c-Myb TAD is expected to increase the KIX-binding affinity. Here, to develop an inhibitor of the c-Myb–KIX interaction, we designed mutants of the c-Myb TAD peptide fragment where the helical structure is stabilized, based on theoretical predictions using AGADIR. Three of the four initially designed peptides each had a different Lys-to-Arg substitution on the helix surface opposite the KIX-binding interface. Furthermore, the triple mutant with three Lys-to-Arg substitutions, named RRR, showed a high helical propensity and achieved three-fold higher affinity to KIX than the wild-type TAD with a dissociation constant of 80 nM. Moreover, the RRR inhibitor efficiently competed out the c-Myb–KIX interaction. These results suggest that stabilizing the helical structure based on theoretical predictions, especially by conservative Lys-to-Arg substitutions, is a simple and useful strategy for designing helical peptide inhibitors of protein–protein interactions.
Highlights
Disordered proteins (IDPs) play important roles in living cells, including transcription, translation, and cell cycle r egulation[1,2,3,4]
Our results suggest that stabilizing the helical structure based on theoretical predictions, especially Lys-to-Arg substitutions, is a useful strategy for designing helical peptide inhibitors of protein–protein interactions (PPIs)
Since helix formation is a prerequisite for binding via the conformational selection mechanism, stabilizing the Myb[32] helical structure should accelerate the apparent binding rate and increase the binding affinity to KIX
Summary
Disordered proteins (IDPs) play important roles in living cells, including transcription, translation, and cell cycle r egulation[1,2,3,4]. KIX has two different binding sites, “the c-Myb/pKID site” and “the MLL site.” Both sites interact with the intrinsically disordered regions of various transcription factors, including c-Myb, CREB, and p53 on the c-Myb/pKID site[29,30,31] and a mixed lineage leukemia protein (MLL), c-Jun, p53, HIV-1 Tat, and HBZ on the MLL s ite[32,33,34,35,36]. Inhibitors of the c-Myb–KIX interaction, which bind the c-Myb/pKID site of KIX, may inhibit the diseases caused by PPIs at this site. Myb[32] is a suitable template for designing peptide inhibitors
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.