Phosphoproteomic analysis of human mitotic chromosomes identified a chromokinesin KIF4A.
Protein phosphorylation is the prime post-translational modification to drive cell division. Identification of phosphorylated proteins and their related kinases has uncovered molecular networks underlying mitotic processes, including chromosome assembly. Here we aimed to identify phosphoproteins from a mitotic chromosome-enriched lysate biochemically using mass spectrometry. We employed the Polo-box domain (PBD) of Polo-like kinase to tether phosphorylated proteins in the lysate. Resulting candidates included a number of chromosomal proteins that would not be identified unless using chromosome-enriched fractions. Among them, we focused to a chromokinesin KIF4A which becomes concentrated along the longitudinal axis of mitotic condensed chromatids. We found that KIF4A is phosphorylated specifically during mitosis, depending on the activity of Cdk1 and Aurora B, which turned out to be required for KIF4A to interact with condensin I. The molecular link between KIF4A and condensin raises an interesting possibility that the interaction of two distantly related ATPases is triggered by mitotic phosphorylation.
Division of Experimental Pathology, Cancer Institute of the Japanese Foundation for Cancer Research (JFCR).
Motoko
M
Takahashi
Kozo
K
Tanaka
Toshifumi
T
Wakai
Toru
T
Hirota
D002460:Cell Line; D002877:Chromosomes, Human / Q000378:metabolism*; D006801:Humans; D016547:Kinesins / Q000378:metabolism*; D008938:Mitosis; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011499:Protein Processing, Post-Translational; D020543:Proteome; D040901:Proteomics / Q000379:methods
D010750:Phosphoproteins; D020543:Proteome; C484228:KIF4A protein, human; D016547:Kinesins