Autoinhibition and relief mechanism for Polo-like kinase 4

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 112; no. 7; pp. E657 - E666
• Main Authors: Klebba, Joseph E., Buster, Daniel W., McLamarrah, Tiffany A., Rusan, Nasser M., Rogers, Gregory C.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 17.02.2015; National Acad Sciences
• Series: PNAS Plus
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Biological Sciences; Cell Line; Dimerization; DNA Primers; Drosophila; Drosophila Proteins - antagonists & inhibitors; Drosophila Proteins - chemistry; Drosophila Proteins - metabolism; Enzymes; Kinases; Microscopy, Fluorescence; Molecular Sequence Data; Native Polyacrylamide Gel Electrophoresis; Phosphorylation; PNAS Plus; Protein-Serine-Threonine Kinases - antagonists & inhibitors; Protein-Serine-Threonine Kinases - chemistry; Protein-Serine-Threonine Kinases - metabolism; Sequence Homology, Amino Acid; Tandem Mass Spectrometry; Ubiquitination; Polo-like kinase 4; Polo box; autoinhibition; centriole; centrosome
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1417967112

Polo-like kinase 4 (Plk4) is a master regulator of centriole duplication, and its hyperactivity induces centriole amplification. Homodimeric Plk4 has been shown to be ubiquitinated as a result of autophosphorylation, thus promoting its own degradation and preventing centriole amplification. Unlike other Plks, Plk4 contains three rather than two Polo box domains, and the function of its third Polo box (PB3) is unclear. Here, we performed a functional analysis of Plk4’s structural domains. Like other Plks, Plk4 possesses a previously unidentified autoinhibitory mechanism mediated by a linker (L1) near the kinase domain. Thus, autoinhibition is a conserved feature of Plks. In the case of Plk4, autoinhibition is relieved after homodimerization and is accomplished by PB3 and by autophosphorylation of L1. In contrast, autophosphorylation of the second linker promotes separation of the Plk4 homodimer. Therefore, autoinhibition delays the multiple consequences of activation until Plk4 dimerizes. These findings reveal a complex mechanism of Plk4 regulation and activation which govern the process of centriole duplication. Significance Polo-like kinases (Plks) are a conserved family of enzymes that function as master regulators for the process of cell division. Among their duties, Plks control the assembly of centrosomes, tiny organelles that facilitate mitotic spindle assembly and maintain the fidelity of chromosome inheritance. Plks are overexpressed in cancer, and therefore it is critical to unravel the normal regulation of these kinases. Here, we studied Plk4 regulation whose activity controls centrosome number. We showed that, as do other Plks, Plk4 autoinhibits its kinase activity. However, Plk4 is unique in its ability to relieve autoinhibition through a third Polo box domain not present in other Plk family members. Moreover, autoinhibition controls Plk4 oligomerization, which ultimately governs its stability and thus centrosome duplication.