Identification of a consensus motif for Plk (Polo-like kinase) phosphorylation reveals Myt1 as a Plk1 substrate.
Plk1 (Polo-like kinase 1), an evolutionarily conserved serine/threonine kinase, is crucially involved in multiple events during the M phase. Here we have identified a consensus phosphorylation sequence for Plk1, by testing the ability of systematically mutated peptides derived from human Cdc25C to serve as a substrate for Plk1. The obtained results show that a hydrophobic amino acid at position +1 carboxyl-terminal of phosphorylated Ser/Thr and an acidic amino acid at position -2 are important for optimal phosphorylation by Plk1. We have then found that Myt1, an inhibitory kinase for MPF, has a number of putative phosphorylation sites for Plk1 in its COOH-terminal portion. While wild-type Myt1 (Myt1-WT) served as a good substrate for Plk1 in vitro, a mutant Myt1 (Myt1-4A), in which the four putative phosphorylation sites are replaced by alanines, did not. In nocodazole-treated cells, Myt1-WT, but not Myt1-4A, displayed its mobility shift in gel electrophoresis, due to phosphorylation. These results suggest that Plk1 phosphorylates Myt1 during M phase. Thus, this study identifies a novel substrate for Plk1 by determining a consensus phosphorylation sequence by Plk1.
Department of Cell and Developmental Biology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Kyoto 606-8503, Japan.
Hiroyuki
H
Nakajima
Fumiko
F
Toyoshima-Morimoto
Eri
E
Taniguchi
Eisuke
E
Nishida
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000737:chemistry; D016193:G1 Phase; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins; D008938:Mitosis; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry*; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D013912:Threonine / Q000737:chemistry; D014162:Transfection; D014981:Xenopus; D029867:Xenopus Proteins; D020687:cdc25 Phosphatases / Q000737:chemistry; D000097869:Polo-Like Kinase 1
D018797:Cell Cycle Proteins; D005982:Glutathione Transferase; D008565:Membrane Proteins; D010455:Peptides; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D012694:Serine; D013912:Threonine; D029867:Xenopus Proteins; D020687:cdc25 Phosphatases; D000097869:Polo-Like Kinase 1; C095970:MYT1 kinase, Xenopus; C490679:PKMYT1 protein, human; C517009:CDC25C protein, human