Revisiting the Multisite Phosphorylation That Produces the M-Phase Supershift of Key Mitotic Regulators

Authors

Tan Tan
Chuanfen Wu
Boye Liu
Bih-Fang Pan
David H Hawke
Zehao Su
Shuaishuai Liu
Wei Zhang
Ruoning Wang
Sue-Hwa Lin
Jian Kuang

Publication Date

10-1-2022

Journal

Molecular Biology of the Cell

Abstract

The term M-phase supershift denotes the phosphorylation-dependent substantial increase in the apparent molecular weight of numerous proteins of varied biological functions during M-phase induction. Although the M-phase supershift of multiple key mitotic regulators has been attributed to the multisite phosphorylation catalyzed by the Cdk1/cyclin B/Cks complex, this view is challenged by multiple lines of paradoxical observations. To solve this problem, we reconstituted the M-phase supershift of Xenopus Cdc25C, Myt1, Wee1A, APC3, and Greatwall in Xenopus egg extracts and characterized the supershift-producing phosphorylations. Our results demonstrate that their M-phase supershifts are each due to simultaneous phosphorylation of a considerable portion of S/T/Y residues in a long intrinsically disordered region that is enriched in both S/T residues and S/TP motifs. Although the major mitotic kinases in Xenopus egg extracts, Cdk1, MAPK, Plx1, and RSK2, are able to phosphorylate the five mitotic regulators, they are neither sufficient nor required to produce the M-phase supershift. Accordingly, inhibition of the four major mitotic kinase activities in Xenopus oocytes did not inhibit the M-phase supershift in okadaic acid-induced oocyte maturation. These findings indicate that the M-phase supershift is produced by a previously unrecognized category of mitotic phosphorylation that likely plays important roles in M-phase induction.

Keywords

Animals, CDC2 Protein Kinase, Cell Cycle Proteins, Cyclin B, Mitosis, Okadaic Acid, Oocytes, Phosphorylation, Xenopus Proteins, Xenopus laevis

Comments

Supplementary Materials

PMID: 35976701