title: Proteomic screen defines the Polo-box domain interactome and identifies Rock2 as a Plk1 substrate.
abstract: Polo-like kinase-1 (Plk1) phosphorylates a number of mitotic substrates, but the diversity of Plk1-dependent processes suggests the existence of additional targets. Plk1 contains a specialized phosphoserine-threonine binding domain, the Polo-box domain (PBD), postulated to target the kinase to its substrates. Using the specialized PBD of Plk1 as an affinity capture agent, we performed a screen to define the mitotic Plk1-PBD interactome by mass spectrometry. We identified 622 proteins that showed phosphorylation-dependent mitosis-specific interactions, including proteins involved in well-established Plk1-regulated processes, and in processes not previously linked to Plk1 such as translational control, RNA processing, and vesicle transport. Many proteins identified in our screen play important roles in cytokinesis, where, in mammalian cells, the detailed mechanistic role of Plk1 remains poorly defined. We go on to characterize the mitosis-specific interaction of the Plk1-PBD with the cytokinesis effector kinase Rho-associated coiled-coil domain-containing protein kinase 2 (Rock2), demonstrate that Rock2 is a Plk1 substrate, and show that Rock2 colocalizes with Plk1 during cytokinesis. Finally, we show that Plk1 and RhoA function together to maximally enhance Rock2 kinase activity in vitro and within cells, and implicate Plk1 as a central regulator of multiple pathways that synergistically converge to regulate actomyosin ring contraction during cleavage furrow ingression.
authors: Department of Biology, Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors: Drew M
authors: DM
authors: Lowery
authors: Karl R
authors: KR
authors: Clauser
authors: Majbrit
authors: M
authors: Hjerrild
authors: Dan
authors: D
authors: Lim
authors: Jes
authors: J
authors: Alexander
authors: Kazuhiro
authors: K
authors: Kishi
authors: Shao-En
authors: SE
authors: Ong
authors: Steen
authors: S
authors: Gammeltoft
authors: Steven A
authors: SA
authors: Carr
authors: Michael B
authors: MB
authors: Yaffe
mesh_terms: D000205:Actomyosin / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D019295:Computational Biology; D048749:Cytokinesis; D004789:Enzyme Activation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D020543:Proteome / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein / Q000378:metabolism*; D000097869:Polo-Like Kinase 1
chemical_list: D000205:Actomyosin; D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D020543:Proteome; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D054460:rho-Associated Kinases; D020742:rhoA GTP-Binding Protein; D000097869:Polo-Like Kinase 1; C515852:ROCK2 protein, human