5EIB

Crystal structure of CPAP PN2-3 C-terminal loop-helix in complex with DARPin-tubulin

Summary for 5EIB

• Entry DOI: 10.2210/pdb5eib/pdb
• Descriptor: Tubulin alpha-1B chain, Tubulin beta-2B chain, Designed ankyrin repeat protein, ... (7 entities in total)
• Functional Keywords: pn2-3, tubulin complex, cell cycle
• Biological source: synthetic construct; More
• Cellular location: Cytoplasm, cytoskeleton: P81947 Q6B856; Cytoplasm, cytoskeleton, microtubule organizing center, centrosome : Q9HC77
• Total number of polymer chains: 4
• Total formula weight: 121968.73

Authors

Li, H.,Zheng, X. (deposition date: 2015-10-29, release date: 2016-10-26, Last modification date: 2023-11-08)

Primary citation

Zheng, X.,Ramani, A.,Soni, K.,Gottardo, M.,Zheng, S.,Ming Gooi, L.,Li, W.,Feng, S.,Mariappan, A.,Wason, A.,Widlund, P.,Pozniakovsky, A.,Poser, I.,Deng, H.,Ou, G.,Riparbelli, M.,Giuliano, C.,Hyman, A.A.,Sattler, M.,Gopalakrishnan, J.,Li, H.
Molecular basis for CPAP-tubulin interaction in controlling centriolar and ciliary length
Nat Commun, 7:11874-11874, 2016

PubMed Abstract: 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 β-tubulin at the microtubule outer surface, while an N-terminal helical motif caps microtubule's α-β surface of β-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 β-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.

PubMed: 27306797
DOI: 10.1038/ncomms11874

Experimental method

X-RAY DIFFRACTION (2.1 Å)