An autoinhibitory tyrosine motif in the cell-cycle-regulated Nek7 kinase is released through binding of Nek9

Area of Science:

• Molecular Biology
• Structural Biology
• Biochemistry

Background:

• Mitosis is regulated by protein kinases, with abnormal expression linked to human cancers.
• NIMA-related kinases (NEKs) like Nek2, Nek6, Nek7, and Nek9 are crucial for mitotic progression.

Purpose of the Study:

• To determine the atomic structure of Nek7 and elucidate its regulatory mechanism.
• To investigate the structural basis of autoinhibition in NEKs and its implications for cancer therapy.

Main Methods:

• X-ray crystallography to determine the atomic structures of Nek7 and Nek2.
• Site-directed mutagenesis to create tyrosine mutants of Nek7 and Nek6.
• Biochemical assays to assess kinase activity and regulation by Nek9.

Main Results:

• The atomic structure of Nek7 revealed an autoinhibited conformation, a previously undescribed regulatory mechanism for kinases.
• Nek2 adopts a similar autoinhibited conformation when bound to a drug-like molecule.
• A tyrosine side chain blocks the active site in the autoinhibited state; tyrosine mutants of Nek7 and Nek6 are constitutively active.
• Nek9 interaction enhances Nek6 and Nek7 activity, suggesting tyrosine release from the inhibitory site.

Conclusions:

• A common autoinhibitory conformation exists in Nek7, Nek2, and potentially other NEKs.
• This autoinhibitory mechanism, involving a tyrosine blocking the active site, is a conserved feature.
• The identified autoinhibitory conformation represents a potential therapeutic target for developing selective kinase inhibitors for cancer treatment.