TitleDoublet microtubule inner junction protein FAP20 recruits tubulin to the microtubule lattice.
Publication TypeJournal Article
Year of Publication2023
AuthorsBangera M, Dungdung A, Prabhu S, Sirajuddin M
Date Published2023 Dec 07
KeywordsAxoneme, Cryoelectron Microscopy, Flagella, Microtubules, Tubulin

Doublet microtubules of eukaryotic cilia and flagella are made up of a complete A- and an incomplete B-tubule that are fused together. Of the two fusion points, the outer junction is made of tripartite tubulin connections, while the inner junction contains non-tubulin elements. The latter includes flagellar-associated protein 20 (FAP20) and Parkin co-regulated gene protein (PACRG) that together link the A- and B-tubule at the inner junction. While structures of doublet microtubules reveal molecular details, their assembly is poorly understood. In this study, we purified recombinant FAP20 and characterized its effects on microtubule dynamics. We use in vitro reconstitution and cryo-electron microscopy to show that FAP20 recruits free tubulin to the existing microtubule lattice. Our cryo-electron microscopy reconstruction of microtubule:FAP20:tubulin complex reveals the mode of tubulin recruitment by FAP20 onto microtubules, providing insights into assembly steps of B-tubule closure during doublet microtubule formation.

Alternate JournalStructure
PubMed ID37816351
PubMed Central IDPMC7615566
Grant List / WT_ / Wellcome Trust / United Kingdom
IA/I/14/2/501533 / WTDBT_ / DBT-Wellcome Trust India Alliance / India