skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Structure of Calmodulin Bound to a Calcineurin Peptide: A New Way of Making an Old Binding Mode

Abstract

Calcineurin is a calmodulin-binding protein in brain and the only serine/threonine protein phosphatase under the control of Ca{sup 2+}/calmodulin (CaM), which plays a critical role in coupling Ca{sup 2+} signals to cellular responses. CaM up-regulates the phosphatase activity of calcineurin by binding to the CaM-binding domain (CBD) of calcineurin subunit A. Here, we report crystal structural studies of CaM bound to a CBD peptide. The chimeric protein containing CaM and the CBD peptide forms an intimate homodimer, in which CaM displays a native-like extended conformation and the CBD peptide shows -helical structure. Unexpectedly, the N-terminal lobe from one CaM and the C-terminal lobe from the second molecule form a combined binding site to trap the peptide. Thus, the dimer provides two binding sites, each of which is reminiscent of the fully collapsed conformation of CaM commonly observed in complex with, for example, the myosin light chain kinase (MLCK) peptide. The interaction between the peptide and CaM is highly specific and similar to MLCK.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
914079
Report Number(s):
BNL-78647-2007-JA
Journal ID: ISSN 0006-2960; BICHAW; TRN: US0801526
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Biochemistry; Journal Volume: 45; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BRAIN; CALMODULIN; CHAINS; DIMERS; MYOSIN; PEPTIDES; PHOSPHATASES; PROTEINS; NSLS; national synchrotron light source

Citation Formats

Ye,Q., Li, X., Wong, A., Wei, Q., and Jia, Z. Structure of Calmodulin Bound to a Calcineurin Peptide: A New Way of Making an Old Binding Mode. United States: N. p., 2006. Web. doi:10.1021/bi0521801.
Ye,Q., Li, X., Wong, A., Wei, Q., & Jia, Z. Structure of Calmodulin Bound to a Calcineurin Peptide: A New Way of Making an Old Binding Mode. United States. doi:10.1021/bi0521801.
Ye,Q., Li, X., Wong, A., Wei, Q., and Jia, Z. Sun . "Structure of Calmodulin Bound to a Calcineurin Peptide: A New Way of Making an Old Binding Mode". United States. doi:10.1021/bi0521801.
@article{osti_914079,
title = {Structure of Calmodulin Bound to a Calcineurin Peptide: A New Way of Making an Old Binding Mode},
author = {Ye,Q. and Li, X. and Wong, A. and Wei, Q. and Jia, Z.},
abstractNote = {Calcineurin is a calmodulin-binding protein in brain and the only serine/threonine protein phosphatase under the control of Ca{sup 2+}/calmodulin (CaM), which plays a critical role in coupling Ca{sup 2+} signals to cellular responses. CaM up-regulates the phosphatase activity of calcineurin by binding to the CaM-binding domain (CBD) of calcineurin subunit A. Here, we report crystal structural studies of CaM bound to a CBD peptide. The chimeric protein containing CaM and the CBD peptide forms an intimate homodimer, in which CaM displays a native-like extended conformation and the CBD peptide shows -helical structure. Unexpectedly, the N-terminal lobe from one CaM and the C-terminal lobe from the second molecule form a combined binding site to trap the peptide. Thus, the dimer provides two binding sites, each of which is reminiscent of the fully collapsed conformation of CaM commonly observed in complex with, for example, the myosin light chain kinase (MLCK) peptide. The interaction between the peptide and CaM is highly specific and similar to MLCK.},
doi = {10.1021/bi0521801},
journal = {Biochemistry},
number = 3,
volume = 45,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • The interaction between the peptide corresponding to the calmodulin-binding domain of smooth muscle myosin light-chain kinase and (Ca{sup 2+}){sub 4}-calmodulin has been studied by multinuclear and multidimensional nuclear magnetic resonance methods. The study was facilitated by the use of {sup 15}N-labeled peptide in conjunction with {sup 15}N-edited and {sup 15}N-correlated {sup 1}H spectroscopy. The peptide forms a 1:1 complex with calcium-saturated calmodulin which is in slow exchange with free peptide. The {sup 1}H and {sup 15}N resonances of the bound have been assigned. An extensive set of structural constraints for the bound peptide has been assembled from the analysis ofmore » nuclear Overhauser effects and three-bond coupling constants. The backbone conformation of the bound peptide has been determined using these constraints by use of distance geometry and related computational methods. The backbone conformation of the peptide has been determined to high precision and is generally indicative of helical secondary structure. Nonhelical backbone conformations are seen in the middle and at the C-terminal end of the bound peptide. These studies provide the first direct confirmation of the amphiphilic helix model for the structure of peptides bound to calcium-saturated calmodulin.« less
  • Small-angle X-ray and neutron scattering data were used to study the solution structure of calmodulin complexed with a synthetic peptide corresponding to residues 577-603 of rabbit skeletal muscle myosin light chain kinase. The X-ray data indicate that, in the presence of Ca{sup 2+}, the calmodulin-peptide complex has a structure that is considerably more compact than uncomplexed calmodulin. The radius of gyration, R{sub g}, for the complex is approximately 20% smaller than that of uncomplexed Ca{sup 2+}{center dot}calmodulin, and the maximum dimension, d{sub max}, for the complex is also about 20% smaller. The peptide-induced conformational rearrangement of calmodulin is (Ca{sup 2+})more » dependent. The length distribution function for the complex is more symmetric than that for uncomplexed Ca{sup 2+}{center dot}calmodulin, indicating that more of the mass is distributed toward the center of mass for the complex, compared with the dumbbell-shaped Ca{sup 2+}{center dot}calmodulin. The solvent contrast dependence of R{sub g} for neutron scattering indicates that the peptide is located more toward the center of the complex, while the calmodulin is located more peripherally, and that the centers of mass of the calmodulin and the peptide are not coincident. The scattering data support the hypothesis that the interconnecting helix region observed in the crystal structure for calmodulin is quite flexible in solution, allowing the two lobes of calmodulin to form close contacts on binding the peptide. This flexibility of the central helix may play a critical role in activating target enzymes such as myosin light chain kinase.« less
  • The interaction between calcium-saturated chicken calmodulin and a peptide corresponding to the calmodulin-binding domain of the chicken smooth muscle myosin light chain kinase has been studied by multinuclear and multidimensional nuclear magnetic resonance methods. Extensive {sup 1}H and {sup 15}N resonance assignments of calmodulin in the complex have been obtained from the analysis of two- and three-dimensional nuclear magnetic resonance spectra. The assignment of calmodulin in the complex was facilitated by the use of selective labeling of the protein with {alpha}-{sup 15}N-labeled valine, alanine, lysine, leucine, and glycine. These provided reference points during the main-chain-directed analysis of three-dimensional spectra ofmore » complexes prepared with uniformly {sup 15}N-labeled calmodulin. The pattern of nuclear Overhauser effects (NOE) seen among main-chain amide NH, C{sub {alpha}}H, and C{sub {beta}}H hydrogens indicates that the secondary structure of the globular domains of calmodulin in the complex closely corresponds to that observed in the calcium-saturated state of the protein in the absence of bound peptide. However, the backbone conformation of residues 76-84 adopts an extended chain conformation upon binding of the peptide in contrast to its helical conformation in the absence of peptide. A sufficient number of NOEs between the globular domains of calmodulin and the bound peptide have been found to indicate that the N- and C-terminal regions of the peptide interact with the C- and N-terminal domains of calmodulin, respectively. The significance of these results are discussed in terms of recently proposed models for the structure of calmodulin-peptide complexes.« less
  • Cited by 9