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Asterless is a Polo-like kinase 4 substrate that both activates and inhibits kinase activity depending on its phosphorylation state

Authors :
Gregory C. Rogers
Tiffany A. McLamarrah
Cody J. Boese
Kevin C. Slep
Nasser M. Rusan
Jonathan Nye
Daniel W. Buster
Amy E. Byrnes
Source :
Molecular Biology of the Cell
Publication Year :
2018
Publisher :
American Society for Cell Biology (ASCB), 2018.

Abstract

Centriole assembly initiates when Polo-like kinase 4 (Plk4) interacts with a centriole “targeting-factor.” In Drosophila, Asterless/Asl (Cep152 in humans) fulfills the targeting role. Interestingly, Asl also regulates Plk4 levels. The N-terminus of Asl (Asl-A; amino acids 1-374) binds Plk4 and promotes Plk4 self-destruction, although it is unclear how this is achieved. Moreover, Plk4 phosphorylates the Cep152 N-terminus, but the functional consequence is unknown. Here, we show that Plk4 phosphorylates Asl and mapped 13 phospho-residues in Asl-A. Nonphosphorylatable alanine (13A) and phosphomimetic (13PM) mutants did not alter Asl function, presumably because of the dominant role of the Asl C-terminus in Plk4 stabilization and centriolar targeting. To address how Asl-A phosphorylation specifically affects Plk4 regulation, we generated Asl-A fragment phospho-mutants and expressed them in cultured Drosophila cells. Asl-A-13A stimulated kinase activity by relieving Plk4 autoinhibition. In contrast, Asl-A-13PM inhibited Plk4 activity by a novel mechanism involving autophosphorylation of Plk4’s kinase domain. Thus, Asl-A’s phosphorylation state determines which of Asl-A’s two opposing effects are exerted on Plk4. Initially, nonphosphorylated Asl binds Plk4 and stimulates its kinase activity, but after Asl is phosphorylated, a negative-feedback mechanism suppresses Plk4 activity. This dual regulatory effect by Asl-A may limit Plk4 to bursts of activity that modulate centriole duplication.

Details

ISSN :
19394586 and 10591524
Volume :
29
Database :
OpenAIRE
Journal :
Molecular Biology of the Cell
Accession number :
edsair.doi.dedup.....beafa3eb046e6042f5b9b6ee22879a2a