Purification and Cloning of a Protein Kinase That Phosphorylates and Activates the Polo-Like Kinase Plx1

• Published in: Science (American Association for the Advancement of Science) Vol. 282; no. 5394; pp. 1701 - 1704
• Main Authors: Qian, Yue-Wei, Erikson, Eleanor, Maller, James L.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 27.11.1998; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Adenosine Triphosphate - metabolism; Amino Acid Sequence; Amino acids; Animals; Antibodies; Biological and medical sciences; Catalytic Domain; Cell cycle; Cell Cycle Proteins; Cell cycle, cell proliferation; Cell division; Cell physiology; Chromatography; Cloning; Cloning, Molecular; Eggs; Enzyme Activation; Enzymes; Feedback (Response); Frogs; Fundamental and applied biological sciences. Psychology; Gels; Mitosis; Molecular and cellular biology; Molecular Sequence Data; Okadaic Acid - pharmacology; Oocytes; Oocytes - enzymology; Peptide Mapping; Phosphoprotein Phosphatases - metabolism; Phosphorylation; Progesterone - pharmacology; Protein kinases; Protein-Serine-Threonine Kinases - chemistry; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - isolation & purification; Protein-Serine-Threonine Kinases - metabolism; Recombinant Fusion Proteins - metabolism; Resins; Xenopus; Xenopus Proteins; Phosphorylation; Purification; Nucleotide sequence; Enzyme; Mitosis; Transferases; Xenopus laevis; Amphibia; Homology; Salientia; Signal transduction; Vertebrata; Regulation(control); Enzymatic activity; Gene; Protein kinase; Cell cycle
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.282.5394.1701

The Xenopus polo-like kinase 1 (Plx1) is essential during mitosis for the activation of Cdc25C, for spindle assembly, and for cyclin B degradation. Polo-like kinases from various organisms are activated by phosphorylation by an unidentified protein kinase. A protein kinase, polo-like kinase kinase 1 or xPlkk1, that phosphorylates and activates Plx1 in vitro was purified to near homogeneity and cloned. Phosphopeptide mapping of Plx1 phosphorylated in vitro by recombinant xPlkk1 or in progesterone-treated oocytes indicates that xPlkk1 may activate Plx1 in vivo. The xPlkk1 protein itself was also activated by phosphorylation on serine and threonine residues, and the kinetics of activation of xPlkk1 in vivo closely paralleled the activation of Plx1. Moreover, microinjection of xPlkk1 into Xenopus oocytes accelerated the timing of activation of Plx1 and the transition from G$_2$ to M phase of the cell cycle. These results define a protein kinase cascade that regulates several events of mitosis.