Structure-based identification of CaMKIIα-interacting MUPP1 PDZ domains and rational design of peptide ligands to target such interaction in human fertilization

Autor: Ying-Pu Sun, Yi-Le Zhang, Zhao-Feng Han
Rok vydání: 2016
Předmět:
Zdroj: Amino Acids. 48:1509-1521
ISSN: 1438-2199
0939-4451
DOI: 10.1007/s00726-016-2211-6
Popis: The recognition and association between Ca2+/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–COOH of the C-terminal peptide SGAPSV–COOH 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 d = 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 ΔG total = −7.6 and −9.2 kcal/mol for peptide binding to PDZ 5 and 11, respectively). A systematic mutation of SGAPSV–COOH 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–COOH and SIVMNV–COOH) were identified to have considerably improved affinity with K d 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–COOH, SGLPNV–COOH, SIVMSV–COOH, SIVPNV–COOH and SIAMNV–COOH) possessed comparable affinity with the wild type, and they may be further optimized to obtain higher potency.
Databáze: OpenAIRE
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