Structure of the Ca2+/S100B/NDR Kinase Peptide Complex: Insights into S100 Target Specificity and Activation of the Kinase

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• 作者：Shibani Bhattacharya ; Edward Large ; Claus W. Heizmann ; Brian A. Hemmings ; and Walter J. Chazin
• 刊名：Biochemistry
• 出版年：2003
• 出版时间：December 16, 2003
• 年：2003
• 卷：42
• 期：49
• 页码：14416 - 14426
• 全文大小：910K
• 年卷期：v.42,no.49(December 16, 2003)
• ISSN：1520-4995

文摘

NDR, a nuclear serine/threonine kinase, belongs to the subfamily of Dbf2 kinases that is criticalto the morphology and proliferation of cells. The activity of NDR kinase is modulated in a Ca²⁺/S100B-dependent manner by phosphorylation of Ser281 in the catalytic domain and Thr444 in the C-terminalregulatory domain. S100B, which is a member of the S100 subfamily of EF-hand proteins, binds to abasic/hydrophobic sequence at the junction of the N-terminal regulatory and catalytic domains (NDR_62-87).Unlike calmodulin-dependent kinases, regulation of NDR by S100B is not associated with directautoinhibition of the active site, but rather involves a conformational change in the catalytic domain triggeredby Ca²⁺/S100B binding to the junction region. To gain further insight into the mechanism of activationof the kinase, studies have been carried out on Ca²⁺/S100B in complex with the intact N-terminal regulatorydomain, NDR_1-87. Multidimensional heteronuclear NMR analysis showed that the binding mode andstoichiometry of a peptide fragment of NDR (NDR_62-87) is the same as for the intact N-terminal regulatorydomain. The solution structure of Ca²⁺/S100B and NDR_62-87 has been determined. One target moleculeis found to associate with each subunit of the S100B dimer. The peptide adopts three turns of helix in thebound state, and the complex is stabilized by both hydrophobic and electrostatic interactions. These structuralstudies, in combination with available biochemical data, have been used to develop a model for calcium-induced activation of NDR kinase by S100B.