Chlamydomonas axonemal dynein assembly locus ODA8 encodes a conserved flagellar protein needed for cytoplasmic maturation of outer dynein arm complexes

Abstract

The Chlamydomonas reinhardtii oda8 mutation blocks assembly of flagellar outer dynein arms, and interacts genetically with oda5 and oda10, which encode axonemal proteins thought to aid dynein binding onto axonemal docking sites. We positionally cloned ODA8 and identified the gene product as the algal homolog of vertebrate LRRC56. Its flagellar localization depends on ODA5 and ODA10, consistent with genetic interaction studies, but phylogenomics suggests that LRRC56 homologs play a role in intraflagellar transport (IFT)-dependent assembly of outer row dynein arms, not axonemal docking. ODA8 distribution between cytoplasm and flagella is similar to that of IFT proteins and about half of flagellar ODA8 is in the soluble matrix fraction. Dynein extracted in vitro from wild type axonemes will rebind efficiently to oda8 mutant axonemes, without rebinding of ODA8, further supporting a role in dynein assembly or transport, not axonemal binding. Assays comparing preassembled outer dynein arm complexes from the cytoplasm of wild type and mutant strains show that dynein in oda8 mutant cytoplasm has not properly preassembled and cannot bind normally onto oda axonemes. We conclude that ODA8 plays an important role in formation and transport of mature dynein complexes during flagellar assembly.

Sperm dysfunction and ciliopathy

“…The complex is associated with an adenylate kinase with sequence similarity to human cytosolic AK1 and AK5 [155]. ODA8 is localized to both the flagellar matrix and cytoplasm, similar to IFT components [157]. Thus, this accessory complex might be involved in IFT-dependent assembly of the OAD before docking onto the doublet microtubules.…”

Rare Human Diseases: Model Organisms in Deciphering the Molecular Basis of Primary Ciliary Dyskinesia

“…The depletion of the LRRC56-like protein in Trypanosoma affects the assembly of the ODAs, but only in the distal part of the axoneme [224]. Flagella assembled by Chlamydomonas oda8 mutants lack ODAs; it is proposed that ODA8 participates in the maturation and transport of ODAs to flagella [226]. Thus, ODA8 is either not a true ortholog of LRRC56 or, if these proteins are orthologous, they play different roles in human cilia and in the flagella of the unicellular organisms.…”

Biallelic Mutations in LRRC56, Encoding a Protein Associated with Intraflagellar Transport, Cause Mucociliary Clearance and Laterality Defects

“…42 The protein contains five leucine-rich repeat domains conserved across species whose motile cilia are assembled by intraflagellar transport (IFT). 43 LRRC56 is the human ortholog of the Chlamydomonas reinhardtii gene oda8, which is thought to play a role in the maturation and/or transport of outer dynein arm (ODA) complexes during flagellum assembly and has a biochemical distribution similar to IFT proteins. 43 ODA8 is proposed to function together with two other proteins termed ODA5 and ODA10 to form an accessory complex involved in assembly and transport of ODA during axoneme assembly.…”

“…43 LRRC56 is the human ortholog of the Chlamydomonas reinhardtii gene oda8, which is thought to play a role in the maturation and/or transport of outer dynein arm (ODA) complexes during flagellum assembly and has a biochemical distribution similar to IFT proteins. 43 ODA8 is proposed to function together with two other proteins termed ODA5 and ODA10 to form an accessory complex involved in assembly and transport of ODA during axoneme assembly. 43 However, evidence for a physical interaction is lacking, and the exact role of ODA8 remains to be defined.…”

“…43 ODA8 is proposed to function together with two other proteins termed ODA5 and ODA10 to form an accessory complex involved in assembly and transport of ODA during axoneme assembly. 43 However, evidence for a physical interaction is lacking, and the exact role of ODA8 remains to be defined. To evaluate a possible association of LRRC56 with the multi-subunit IFT machinery, HEK293 cells were co-transfected with plasmids encoding human LRRC56 tagged with V5 and the reference IFT protein IFT88 fused to eYFP.…”