Shulin packages axonemal outer dynein arms for ciliary targeting

Girish R. Mali; Ferdos Abid Ali; Clinton K. Lau; Farida Begum; Jérôme Boulanger A; Jonathan D. Howe; Zhuo Angel Chen; Juri Rappsilber; Mark J. Skehel; Andrew P. Carter

doi:10.1126/science.abe0526

Molecular BiologyScienceFeb 25, 2021

Peer-reviewed journal article

Shulin packages axonemal outer dynein arms for ciliary targeting

Girish R. Mali iD, Ferdos Abid Ali iD, Clinton K. Lau iD, Farida Begum iD, Jérôme Boulanger A iD, Jonathan D. Howe iD, Zhuo Angel Chen iD, Juri Rappsilber iD, Mark J. Skehel iD, Andrew P. Carter iD

Abstract

The main force generators in eukaryotic cilia and flagella are axonemal outer dynein arms (ODAs). During cilio-genesis, these [~]1.8 MDa complexes are assembled in the cytoplasm and targeted to cilia via an unknown mechanism. Here we use the ciliate Tetrahymena to identify two novel factors (Q22YU3 and Q22MS1) which bind ODAs in the cytoplasm and are required for their delivery to cilia. We show that Q22YU3, which we name Shulin, locks the ODA motor domains into a closed conformation and inhibits motor activity. Cryo-EM reveals how Shulin stabilizes this compact form of ODAs by binding to the dynein tails. Our findings provide a molecular explanation for how newly assembled dyneins are packaged for delivery to the cilia.

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