An Autoinhibitory Tyrosine Motif in the Cell-Cycle-Regulated Nek7 Kinase Is Released through Binding of Nek9

Abstract

SummaryMitosis is controlled by multiple protein kinases, many of which are abnormally expressed in human cancers. Nek2, Nek6, Nek7, and Nek9 are NIMA-related kinases essential for proper mitotic progression. We determined the atomic structure of Nek7 and discovered an autoinhibited conformation that suggests a regulatory mechanism not previously described in kinases. Additionally, Nek2 adopts the same conformation when bound to a drug-like molecule. In both structures, a tyrosine side chain points into the active site, interacts with the activation loop, and blocks the αC helix. Tyrosine mutants of Nek7 and the related kinase Nek6 are constitutively active. The activity of Nek6 and Nek7, but not the tyrosine mutant, is increased by interaction with the Nek9 noncatalytic C-terminal domain, suggesting a mechanism in which the tyrosine is released from its autoinhibitory position. The autoinhibitory conformation is common to three Neks and provides a potential target for selective kinase inhibitors.

DYNLL/LC8 Protein Controls Signal Transduction through the Nek9/Nek6 Signaling Module by Regulating Nek6 Binding to Nek9

“…Once active, Nek9 is able to directly phosphorylate Nek6 and Nek7 in the activation loop (respectively at Nek6[Ser206] and Nek7[Ser195]), directly activating both kinases (35). In addition, the binding of Nek6/7 to Nek9 has been described to release Nek6/7 from an autoinhibited conformation and thus to directly contribute to their activation (16).…”

“…In vitro, Nek9 is capable of autoactivating through autophosphorylation; in vivo, the kinase is inactive during interphase and is activated at centrosomes and spindle poles during mitosis, when it binds Nek6 and Nek7 and is then able to directly phosphorylate these kinases in the activation loop, in turn inducing their activation (13)(14)(15). Nek6/7 binding to Nek9 has in addition been reported to directly increase the activity of Nek6 and Nek7 by disrupting an autoinhibited conformation of these kinases (16). Despite the importance of the interaction between Nek9 and Nek6/7, how it is physiologically regulated has not been described to date.…”

Structure, function, and evolution of plant NIMA-related kinases: implication for phosphorylation-dependent microtubule regulation

“…Nek9 phosphorylates and activates Nek6 and Nek7 (Roig et al 2002;Belham et al 2003). The autoinhibitory mechanism might be common in at least three Neks, Nek6, Nek7, and Nek2 (Richards et al 2009). Apart from AtNEK6, NEK proteins in A. thaliana also Although the C-terminal tail is structurally divergent, it often contains a coiled-coil domain and PEST sequences (Fig.…”

“…The crystal structure of human Nek7 suggests a novel autoinhibitory mechanism (Richards et al 2009). The inhibitory Tyr-97 residue in NEK7 points down to the catalytic center and prevents the formation of hydrophobic core, which is essential for the catalytic activity of Nek7.…”

“…S1a). Ala substitutions at the putative autophosphorylation sites of AtNEK6 results in a significant decrease in kinase activity (Motose et al 2008), indicating that the similar autoinhibitory mechanism may regulate the activity of plant NEK family members.The crystal structure of human Nek7 suggests a novel autoinhibitory mechanism (Richards et al 2009). The inhibitory Tyr-97 residue in NEK7 points down to the catalytic center and prevents the formation of hydrophobic core, which is essential for the catalytic activity of Nek7.…”