Structural determinants of calmodulin binding to the intracellular C-terminal domain of the metabotropic glutamate receptor 7A.
Calmodulin (CaM) binds in a Ca2+-dependent manner to the intracellular C-terminal domains of most group III metabotropic glutamate receptors (mGluRs). Here we combined mutational and biophysical approaches to define the structural basis of CaM binding to mGluR 7A. Ca2+/CaM was found to interact with mGluR 7A primarily via its C-lobe at a 1:1 CaM:C-tail stoichiometry. Pulldown experiments with mutant CaM and mGluR 7A C-tail constructs and high resolution NMR with peptides corresponding to the CaM binding region of mGluR 7A allowed us to define hydrophobic and ionic interactions required for Ca2+/CaM binding and identified a 1-8-14 CaM-binding motif. The Ca2+/CaM.mGluR 7A peptide complex displays a classical wraparound structure that closely resembles that formed by Ca2+/CaM upon binding to smooth muscle myosin light chain kinase. Our data provide insight into how Ca2+/CaM regulates group III mGluR signaling via competition with intracellular proteins for receptor-binding sites.
Scheschonka
Astrid
A
Department of Neurochemistry, Max Planck Institute for Brain Research, 60528 Frankfurt, Germany.
Findlow
Stuart
S
Schemm
Rudolf
R
El Far
Oussama
O
Caldwell
John H
JH
Crump
Matthew P
MP
Holden-Dye
Kate
K
O'Connor
Vincent
V
Betz
Heinrich
H
Werner
Jörn M
JM
D000818:Animals; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology; D002147:Calmodulin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding / Q000502:physiology; D020836:Protein Structure, Quaternary / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D051381:Rats; D018094:Receptors, Metabotropic Glutamate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D040681:Structural Homology, Protein; D013329:Structure-Activity Relationship
D002147:Calmodulin; D046912:Multiprotein Complexes; D018094:Receptors, Metabotropic Glutamate; C102719:metabotropic glutamate receptor 7; D009219:Myosin-Light-Chain Kinase; D002118:Calcium