Chlamydomonas DYX1C1/PF23 is essential for axonemal assembly and proper morphology of inner dynein arms.

• Type of Material: Article
• Authors: Ryosuke Yamamoto, Osaka University; Jagan M. Obbineni, Paul Scherrer Institute; Lea Alford, Emory University; Takahiro Ide, University of Tokyo; Mikito Owa, Emory University; Juyeon Hwang, Emory University; Takahide Kon, Osaka University; Kazuo Inaba, University of Tsukuba; Noliyanda James, Washington University; Stephen M. King, University of Connecticut; Takashi Ishikawa, Paul Scherrer Institute; Winfield Sale, Emory University; Susan K. Dutcher, University of Tsukuba
• Language: English
• Date: 2017-09-11
• Publisher: Public Library of Science
• Publication Version: Final Published Version
• Copyright Statement: © 2017 Yamamoto et al
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1371/journal.pgen.1006996
• Title of Journal or Parent Work: PLoS Genetics
• ISSN: 1553-7390
• Volume: 13
• Issue: 9
• Start Page: e1006996
• End Page: e1006996
• Grant/Funding Information: This study was funded by grants from the NIH (GM051293 to SMK, GM051173 to WSS, and HL128370 to SKD), the Children's Discovery Institute, PD-II-2014-379 to SKD, grant from Swiss National Science Foundation (NF31003A_144035) and National Center of Competence in Biomedical Imaging, Switzerland to TIs, Grants-in-Aid for Scientific Research (15H01201, 15K14566, and 17H01440) from the Ministry of Education, Culture Sports, Science and Technology of Japan to KI, JSPS KAKENHI Grant Numbers JP26291034 and JP17H03665 to TK, JSPS Research Fellowship for Young Scientists to MO, and JSPS Postdoctoral Fellowship for Research Abroad, JSPS Research Fellowship for Young Scientists, and Young Researchers Exchange Program between Japan and Switzerland by Japanese-Swiss Science and Technology Program to RY.
• Keywords: Trypanosoma; Protein domains; Sequence motif analysis; Dyneins; Motor proteins; Cytoplasm; Immunoblotting; Cilia
• Research Categories: Health Sciences, Immunology; Biology, Cell; Biology, Genetics

Abstract

Cytoplasmic assembly of ciliary dyneins, a process known as preassembly, requires numerous non-dynein proteins, but the identities and functions of these proteins are not fully elucidated. Here, we show that the classical Chlamydomonas motility mutant pf23 is defective in the Chlamydomonas homolog of DYX1C1. The pf23 mutant has a 494 bp deletion in the DYX1C1 gene and expresses a shorter DYX1C1 protein in the cytoplasm. Structural analyses, using cryo-ET, reveal that pf23 axonemes lack most of the inner dynein arms. Spectral counting confirms that DYX1C1 is essential for the assembly of the majority of ciliary inner dynein arms (IDA) as well as a fraction of the outer dynein arms (ODA). A C-terminal truncation of DYX1C1 shows a reduction in a subset of these ciliary IDAs. Sucrose gradients of cytoplasmic extracts show that preassembled ciliary dyneins are reduced compared to wild-type, which suggests an important role in dynein complex stability. The role of PF23/DYX1C1 remains unknown, but we suggest that DYX1C1 could provide a scaffold for macromolecular assembly.