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- Title
Structure-based identification of CaMKIIα-interacting MUPP1 PDZ domains and rational design of peptide ligands to target such interaction in human fertilization.
- Authors
Zhang, Yi-Le; Han, Zhao-Feng; Sun, Ying-Pu
- Abstract
The recognition and association between Ca/calmodulin-activated protein kinase II-α (CaMKIIα) and multi-PDZ domain protein 1 (MUPP1) plays an important role in sperm acrosome reaction and human fertilization, which is mediated by the binding of CaMKIIα's C-terminal tail to one or more PDZ domains of the scaffolding protein MUPP1. In this study, we attempt to identify the CaMKIIα-interacting MUPP1 PDZ domains and to design peptide ligands that can potently target and then competitively disrupt such interaction. Here, a synthetic biology approach was proposed to systematically characterize the structural basis, energetic property, dynamic behavior and biological implication underlying the intermolecular interactions between the C-terminal peptide of CaMKIIα and all the 13 PDZ domains of MUPP1. These domains can be grouped into four clusters in terms of their sequence, structure and physiochemical profile; different clusters appear to recognize different classes of PDZ-binding motifs. The cluster 3 includes two members, i.e. MUPP1 PDZ 5 and 11 domains, which were suggested to bind class II motif Φ-X-Φ of the C-terminal peptide SGAPSV of CaMKIIα. Subsequently, the two domains were experimentally measured as the moderate- and high-affinity binders of the peptide by using fluorescence titration (dissociation constants K = 25.2 ± 4.6 and 0.47 ± 0.08 µM for peptide binding to PDZ 5 and 11, respectively), which was in line with theoretical prediction (binding free energies Δ G = −7.6 and −9.2 kcal/mol for peptide binding to PDZ 5 and 11, respectively). A systematic mutation of SGAPSV residues suggested few favorable amino acids at different residue positions of the peptide, which were then combined to generate a number of potent peptide mutants for PDZ 11 domain. Consequently, two peptides (SIAPNV and SIVMNV) were identified to have considerably improved affinity with K increase by ~tenfold relative to wild type peptide. Thus, the two peptides are considered as promising lead entities to develop therapeutic molecular agents with high efficacy and specificity to target CaMKIIα-MUPP1 interaction. Other five designed peptides (SILPSV, SGLPNV, SIVMSV, SIVPNV and SIAMNV) possessed comparable affinity with the wild type, and they may be further optimized to obtain higher potency.
- Subjects
PDZ proteins; DRUG design; C-terminal residues; CONCEPTION; CALMODULIN; DRUG development; DRUG efficacy
- Publication
Amino Acids, 2016, Vol 48, Issue 6, p1509
- ISSN
0939-4451
- Publication type
Article
- DOI
10.1007/s00726-016-2211-6