A novel target recognition revealed by calmodulin in complex with Ca2+-calmodulin-dependent kinase kinase. |
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| Authors: | M Osawa H Tokumitsu M B Swindells H Kurihara M Orita T Shibanuma T Furuya M Ikura |
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| Institution: | Molecular Chemistry Research, Chemistry Laboratories, Institute for Drug Discovery Research, Yamanouchi Pharmaceutical Co., Ltd., Tsukuba 305-8585, Japan. |
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| Abstract: | The structure of calcium-bound calmodulin (Ca2+/CaM) complexed with a 26-residue peptide, corresponding to the CaM-binding domain of rat Ca2+/CaM-dependent protein kinase kinase (CaMKK), has been determined by NMR spectroscopy. In this complex, the CaMKK peptide forms a fold comprising an alpha-helix and a hairpin-like loop whose C-terminus folds back on itself. The binding orientation of this CaMKK peptide by the two CaM domains is opposite to that observed in all other CaM-target complexes determined so far. The N- and C-terminal hydrophobic pockets of Ca2+/CaM anchor Trp 444 and Phe 459 of the CaMKK peptide, respectively. This 14-residue separation between two key hydrophobic groups is also unique among previously determined CaM complexes. The present structure represents a new and distinct class of Ca2+/CaM target recognition that may be shared by other Ca2+/CaM-stimulated proteins. |
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