CCTα and CCTδ chaperonin subunits are essential and required for cilia assembly and maintenance in Tetrahymena

• Autor(a) principal: Seixas, Cecília
• Data de Publicação: 2010
• Outros Autores: Cruto, Teresa, Tavares, Alexandra, Gaertig, Jacek, Soares, Helena
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.21/3043
• topic: Amino acid substitution/genetics; Axoneme/metabolism; Axoneme/pathology; Chaperonin containing TCP-1/metabolism; Cilia/metabolism; Epitopes/metabolism; Gene Knockout techniques; Microtubules/metabolism; Mutation/genetics; Protein subunits/metabolism; Recombinant fusion proteins; Temperature; Tetrahymena; Zygote

Background - The eukaryotic cytosolic chaperonin CCT is a hetero-oligomeric complex formed by two rings connected back-to-back, each composed of eight distinct subunits (CCTalpha to CCTzeta). CCT complex mediates the folding, of a wide range of newly synthesised proteins including tubulin (alpha, beta and gamma) and actin, as quantitatively major substrates. Methodology/Principal findings - We disrupted the genes encoding CCTalpha and CCTdelta subunits in the ciliate Tetrahymena. Cells lacking the zygotic expression of either CCTalpha or CCTdelta showed a loss of cell body microtubules, failed to assemble new cilia and died within 2 cell cycles. We also show that loss of CCT subunit activity leads to axoneme shortening and splaying of tips of axonemal microtubules. An epitope-tagged CCTalpha rescued the gene knockout phenotype and localized primarily to the tips of cilia. A mutation in CCTalpha, G346E, at a residue also present in the related protein implicated in the Bardet Biedel Syndrome, BBS6, also caused defects in cilia and impaired CCTalpha localization in cilia. Conclusions/Significance - Our results demonstrate that the CCT subunits are essential and required for ciliary assembly and maintenance of axoneme structure, especially at the tips of cilia.