Crystal structure of apo-calmodulin bound to the first two IQ motifs of myosin V reveals essential recognition features.
A 2.5-A resolution structure of calcium-free calmodulin (CaM) bound to the first two IQ motifs of the murine myosin V heavy chain reveals an unusual CaM conformation. The C-terminal lobe of each CaM adopts a semi-open conformation that grips the first part of the IQ motif (IQxxxR), whereas the N-terminal lobe adopts a closed conformation that interacts more weakly with the second part of the motif (GxxxR). Variable residues in the IQ motif play a critical role in determining the precise structure of the bound CaM, such that even the consensus residues of different motifs show unique interactions with CaM. This complex serves as a model for the lever arm region of many classes of unconventional myosins, as well as other IQ motif-containing proteins such as neuromodulin and IQGAPs.
Houdusse
Anne
A
Motilité Structurale, Institut Curie, Centre National de la Recherche Scientifique, Unite Mixté de Recherche 144, 26 rue d'Ulm, 75248, Paris Cedex 05, France.
Gaucher
Jean-François
JF
Krementsova
Elena
E
Mui
Suet
S
Trybus
Kathleen M
KM
Cohen
Carolyn
C
D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D002147:Calmodulin / Q000737:chemistry* / Q000378:metabolism; D003001:Cloning, Molecular; D003460:Crystallization; D051379:Mice; D008958:Models, Molecular; D024701:Myosin Type V / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation
D002147:Calmodulin; D024701:Myosin Type V