Structural basis for the extended CAP-Gly domains of p150ᵍˡᵘᵉᵈ binding to microtubules and the implication for tubulin dynamics

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 31; pp. 11347 - 11352
• Main Authors: Wang, Qianmin, Crevenna, Alvaro H., Kunze, Ines, Mizuno, Naoko
• Format: Journal Article
• Language: English
• Published: National Academy of Sciences 05.08.2014; National Acad Sciences
• Subjects: Biological Sciences
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1403135111

p150 ᵍˡᵘᵉᵈ belongs to a group of proteins accumulating at microtubule plus ends (+TIPs). It plays a key role in initiating retrograde transport by recruiting and tethering endosomes and dynein to microtubules. p150 ᵍˡᵘᵉᵈ contains an N-terminal microtubule-binding cytoskeleton-associated protein glycine-rich (CAP-Gly) domain that accelerates tubulin polymerization. Although this copolymerization is well-studied using light microscopic techniques, structural consequences of this interaction are elusive. Here, using electron-microscopic and spectroscopic approaches, we provide a detailed structural view of p150 ᵍˡᵘᵉᵈ CAP-Gly binding to microtubules and tubulin. Cryo-EM 3D reconstructions of p150 ᵍˡᵘᵉᵈ-CAP-Gly complexed with microtubules revealed the recognition of the microtubule surface, including tubulin C-terminal tails by CAP-Gly. These binding surfaces differ from other retrograde initiation proteins like EB1 or dynein, which could facilitate the simultaneous attachment of all accessory components. Furthermore, the CAP-Gly domain, with its basic extensions, facilitates lateral and longitudinal interactions of tubulin molecules by covering the tubulin acidic tails. This shielding effect of CAP-Gly and its basic extensions may provide a molecular basis of the roles of p150 ᵍˡᵘᵉᵈ in microtubule dynamics.