Molecular basis for CPAP-tubulin interaction in controlling centriolar and ciliary length

作者：Zheng, Xiangdong; Ramani, Anand; Soni, Komal; Gottardo, Marco; Zheng, Shuangping; Gooi, Li Ming; Li, Wenjing; Feng, Shan; Mariappan, Aruljothi; Wason, Arpit; Widlund, Per; Pozniakovsky, Andrei; Poser, Ina; Deng, Haiteng; Ou, Guangshuo; Riparbelli, Maria; Giuliano, Callaini; Hyman, Anthony A.; Sattler, Michael; Gopalakrishnan, Jay^*; Li, Haitao^*

来源：Nature Communications, 2016, 7(1): 11874.

DOI：10.1038/ncomms11874

• MICROTUBULE
• PROTEIN
• IDENTIFICATION
• TRANSPORT
• DYNAMICS
• CILIUM
• SYSTEM
• SAS-4

Centrioles and cilia are microtubule-based structures, whose precise formation requires controlled cytoplasmic tubulin incorporation. How cytoplasmic tubulin is recognized for centriolar/ciliary-microtubule construction remains poorly understood. Centrosomal-P4.1-associated-protein (CPAP) binds tubulin via its PN2-3 domain. Here, we show that a C-terminal loop-helix in PN2-3 targets beta-tubulin at the microtubule outer surface, while an N-terminal helical motif caps microtubule's alpha-beta surface of beta-tubulin. Through this, PN2-3 forms a high-affinity complex with GTP-tubulin, crucial for defining numbers and lengths of centriolar/ciliary-microtubules. Surprisingly, two distinct mutations in PN2-3 exhibit opposite effects on centriolar/ciliary-microtubule lengths. CPAP(F375A), with strongly reduced tubulin interaction, causes shorter centrioles and cilia exhibiting doublet-instead of triplet-microtubules. CPAP(EE343RR) that unmasks the beta-tubulin polymerization surface displays slightly reduced tubulin-binding affinity inducing over-elongation of newly forming centriolar/ciliary-microtubules by enhanced dynamic release of its bound-tubulin. Thus CPAP regulates delivery of its bound-tubulin to define the size of microtubule-based cellular structures using a 'clutch-like' mechanism.

• 出版日期2016-6
• 单位清华大学; 四川大学