Identification of a Novel Microtubule-destabilizing Motif in CPAP That Binds to Tubulin Heterodimers and Inhibits Microtubule Assembly

• DOI: 10.1091/mbc.e04-02-0121
• Publication Date: 2004-03-30T01:53:25Z
• Authors: Liang-Yi Hung; Hua-Ling Chen; Ching-Wen Chang; Bor-Ran Li; Tang K. Tang
• Keywords: Cell Nucleus; Centrosome; G2 Phase; 0301 basic medicine; 0303 health sciences; Paclitaxel; Amino Acid Motifs; Apoptosis; Microtubules; 03 medical and health sciences; Tubulin; Humans; Dimerization; Microtubule-Associated Proteins; Cell Division; Cell Proliferation; HeLa Cells; Protein Binding

We have previously identified a new centrosomal protein, centrosomal protein 4.1-associated protein (CPAP), which is associated with the γ-tubulin complex. Here, we report that CPAP carries a novel microtubule-destabilizing motif that not only inhibits microtubule nucleation from the centrosome but also depolymerizes taxol-stabilized microtubules. Deletion mapping and functional analyses have defined a 112-residue CPAP that is necessary and sufficient for microtubule destabilization. This 112-residue CPAP directly recognizes the plus end of a microtubule and inhibits microtubule nucleation from the centrosome. Biochemical and functional analyses revealed that this 112-residue CPAP also binds to tubulin dimers, resulting in the destabilization of microtubules. Using the tetracycline-controlled system (tet-off), we observed that overexpression of this 112-residue CPAP inhibits cell proliferation and induces apoptosis after G2/M arrest. The possible mechanisms of how this 112-residue motif in CPAP that inhibits microtubule nucleation from the centrosome and disassembles preformed microtubules are discussed.