A model for the calmodulin—peptide complex based on the troponin C crystal packing and its similarity to the NMR structure of the calmodulin—myosin light chain kinase peptide complex

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Abstract
In the crystal structure of troponin C, the holo C-domain is bound in a head-to-tail fashion to the A-helix of the apo N-domain of a symmetry-related molecule. Using this interaction, we have proposed a model for the calmodulin-peptide complex. We find that the interaction of the C-domain with the A-helix is similar to that observed in the NMR structure of the calmodulin-myosin light chain kinase (MLCK) peptide complex. This similarity in binding has enabled us to make a precise sequence alignment of the target peptides in the calmodulin-binding cleft and to rationalize the amino acid sequence-dependent binding strengths of various peptides. Our model differs from that proposed by Strynadka and James (Proteins Struct. Funct. Genet. 7, 234–248, 1990) in that the peptides are rotated by 100° in the calmodulin binding cleft.
Funding Information
  • NIH (AR34139)