Alok K. Sharma and Alan C. Rigby Pages 639 - 645 ( 7 )
Protein-protein interactions between the C-terminal domain of Myosin Binding Subunit (MBS) of MLC Phosphatase (MBS<sub>CT180</sub>; C-terminal 180 aa) and the N-terminal coiled coil (CC) leucine zipper (LZ) domain of PKGI α, PKG-Iα<sub>1-159</sub> play an important role in the process of Smooth Muscle Cell relaxation. The paucity of three-dimensional structural information for MBSCT180 prevents an atomic level understanding of the MBS–PKG contractile complex. MBS<sub>CT180</sub> is comprised of three structurally different sub-domains including a non-canonical CC, a CC, and a LZ. Recently we reported polypeptide purification and biophysical characterization of the CC domain and the LZ domain of MBS<sub>CT180</sub> (Sharma et al, Prot Expr Purif 2012). Here we report <sup>1</sup>H, <sup>13</sup>C, <sup>15</sup>N chemical shift assignments of homodimeric CC MBS domain encompassing amino acid residues Asp931-Leu980 using 2D and 3D heteronuclear NMR spectroscopy. Secondary structure analyses deduced from these NMR chemical shift data have identified a contiguous stretch of 36 residues from Phe932 to Ala967 that is involved in the formation of coiled coil α-helical region within CC MBS domain. The N-terminal residue Asp931 and the C-terminally positioned residues Thr968-Ala975, Arg977, and Ser978 adopt nonhelical loop conformations.
2D <sup>1</sup>H-<sup>15</sup>N HSQC, Coiled coil MBS, Leucine zipper PKG-Iα<sub>1-159</sub>, MLCP, NMR assignment, Secondary structure, VSMC.
, Beth Israel Deaconess Medical Center, 99 Brookline Ave, Boston, MA 02215, USA.