NMR Insight into Myosin-Binding Subunit Coiled Coil Structure Reveals Binding Interface with Protein Kinase G-I? Leucine Zipper in Vascular Function.
Related Articles NMR Insight into Myosin-Binding Subunit Coiled Coil Structure Reveals Binding Interface with Protein Kinase G-I? Leucine Zipper in Vascular Function.
J Biol Chem. 2017 Mar 09;:
Authors: Sharma AK, Birrane GG, Anklin C, Rigby AC, Alper SL
Abstract
Nitrovasodilators relax vascular smooth muscle cells (VSMC) in part by modulating the interaction of the C-terminal coiled-coil domain (CC) and/or leucine zipper (LZ) domain of the myosin light-chain phosphatase (MLCP) component, myosin-binding subunit (MBS), with the N-terminal LZ domain of protein kinase G (PKG)-I?. Despite the importance of vasodilation in cardiovascular homeostasis and therapy, our structural understanding of the MBS CC interaction with LZ PKG-I? has remained limited. Here, we report the three-dimensional NMR solution structure of homodimeric CC MBS in which aa 932-967 form a coiled-coil of two monomeric ?-helices in parallel orientation. We found that the structure is stabilized by non-covalent interactions, with dominant contributions from hydrophobic residues at a and d heptad positions. Using NMR chemical shift perturbation (CSP) analysis, we identified a subset of hydrophobic and charged residues of CC MBS (localized within and adjacent to the C-terminal region) contributing to the dimer-dimer interaction interface between homodimeric CC MBS and homodimeric LZ PKG-I?. 15N backbone relaxation NMR revealed the dynamic features of the CC MBS interface residues identified by NMR CSP. Paramagnetic relaxation-enhancement (PRE) and CSP NMR guided HADDOCK modeling of the dimer-dimer interface of the hetero-tetrameric complex exhibits the involvement of non-covalent intermolecular interactions that are localized within and adjacent to the C-terminal regions of each homodimer. These results deepen our understanding of the binding restraints of this CC MBS-LZ PKG-I? low-affinity heterotetrameric complex and allow re-evaluation of the role(s) of MLCP partner polypeptides in regulation of VSMC contractility.
PMID: 28280239 [PubMed - as supplied by publisher]
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