AlphaFold version 2.0 elucidates the binding mechanism between VIPR2 and KS-133, and reveals an S-S bond (Cys25-Cys192) formation of functional significance for VIPR2

The vasoactive intestinal peptide receptor 2 (VIPR2) has attracted attention as a drug target for the treatment of mental disorders, cancer, and immune diseases. In 2021, we identified the peptide KS-133 as a VIPR2-selective antagonist. In this study, we aimed to elucidate the binding mechanism between VIPR2 and KS-133. To this end, VIPR2/KS-133 and VIPR2/vasoactive intestinal peptide (VIP) complex models were constructed through AlphaFold version 2.0 and molecular dynamic simulations. Our models revealed that: (i) both KS-133 and VIP have helical structures, (ii) the interaction residues on VIPR2 for both peptides are similar, and (iii) the orientation of their helices upon their binding to VIPR2 are different by similar to 45 degrees. Interestingly, in the process of constructing the aforementioned models, an S-S bond formation between Cys(25) and Cys(192) of the human VIPR2 was identified. Although these two Cys residues are highly conserved among species (i.e., corresponding to Cys(24) and Cys(191) in the mouse), no previous reports regarding this S-S bond formation exist. In order to clarify the potential role of this S-S bond in the VIPR2 has functional consequences, a cell line expressing the mouse VIPR2(Cys24Ala, Cys191Ala) was generated. During the VIP stimulation of this cell line, the phosphorylation of AKT (a downstream signal marker of VIPR2) was found to be significantly attenuated, thereby suggesting that the S-S bond has a functional significance for VIPR2. Our study not only elucidates the VIPR2-binding mechanism of KS-133 for the first time, but also provides new insights into the structural biology of VIPR2. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, the binding mechanism between VIPR2 and KS-133 was elucidated through the construction of models and simulations. The study also discovered the functional significance of the S-S bond formation between Cys residues in VIPR2.