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Mapping molecules to structure: unveiling secrets of centriole and cilia assembly with near-atomic resolution
Publication . Jana, Swadhin Chandra; Marteil, Gaëlle; Bettencourt-Dias, Mónica
Centrioles are microtubule (MT)-based cylinders that form centrosomes and can be modified into basal bodies that template the axoneme, the ciliary MT skeleton. These MT-based structures are present in all branches of the eukaryotic tree of life, where they have important sensing, motility and cellular architecture-organizing functions. Moreover, they are altered in several human conditions and diseases, including sterility, ciliopathies and cancer. Although the ultrastructure of centrioles and derived organelles has been known for over 50 years, the molecular basis of their remarkably conserved properties, such as their 9-fold symmetry, has only now started to be unveiled. Recent advances in imaging, proteomics and crystallography, allowed the building of 3D models of centrioles and derived structures with unprecedented molecular details, leading to a much better understanding of their assembly and function. Here, we cover progress in this field, focusing on the mechanisms of centriole and cilia assembly.
A structural road map to unveil basal body composition and assembly
Publication . Jana, Swadhin C; Machado, Pedro; Bettencourt-Dias, Mónica
The Basal Body (BB) acts as the template for the axoneme, the microtubule‐basedstructure of cilia and flagella. Although several proteins were recently implicatedin both centriole and BB assembly and function, their molecular mechanisms are stillpoorly characterized. In this issue of The EMBO journal, Li and coworkersdescribe for the first time the near‐native structure of the BB at 33 Åresolution obtained by Cryo‐Electron Microscopy analysis of wild‐type (WT) isolatedChlamydomonas BBs. They identified several uncharacterized non‐tubulinstructures and variations along the length of the BB, which likely reflect thebinding and function of numerous macromolecular complexes. These complexes areexpected to define BB intrinsic properties, such as its characteristic structure andstability. Similarly to the high‐resolution structures of ribosome and nuclear porecomplexes, this study will undoubtedly contribute towards the future analysis ofcentriole and BB biogenesis, maintenance and function.
BLD10/CEP135 Is a Microtubule-Associated Protein that Controls the Formation of the Flagellum Central Microtubule Pair
Publication . Carvalho-Santos, Zita; Machado, Pedro; Alvarez-Martins, Inês; Gouveia, Susana M.; Jana, Swadhin C.; Duarte, Paulo; Amado, Tiago; Branco, Pedro; Freitas, Micael C.; Silva, Sara T.N.; Antony, Claude; Bandeiras, Tiago M.; Bettencourt-Dias, Mónica
Cilia and flagella are involved in a variety of processes and human diseases, including ciliopathies and sterility. Their motility is often controlled by a central microtubule (MT) pair localized within the ciliary MT-based skeleton, the axoneme. We characterized the formation of the motility apparatus in detail in Drosophila spermatogenesis. We show that assembly of the central MT pair starts prior to the meiotic divisions, with nucleation of a singlet MT within the basal body of a small cilium, and that the second MT of the pair only assembles much later, upon flagella formation. BLD10/CEP135, a conserved player in centriole and flagella biogenesis, can bind and stabilize MTs and is required for the early steps of central MT pair formation. This work describes a genetically tractable system to study motile cilia formation and provides an explanation for BLD10/CEP135's role in assembling highly stable MT-based structures, such as motile axonemes and centrioles.
Evolution: Tracing the origins of centrioles, cilia, and flagella
Publication . Carvalho-Santos, Zita; Azimzadeh, Juliette; Pereira-Leal, José B; Bettencourt-Dias, Mónica
Centrioles/basal bodies (CBBs) are microtubule-based cylindrical organelles that nucleate the formation of centrosomes, cilia, and flagella. CBBs, cilia, and flagella are ancestral structures; they are present in all major eukaryotic groups. Despite the conservation of their core structure, there is variability in their architecture, function, and biogenesis. Recent genomic and functional studies have provided insight into the evolution of the structure and function of these organelles.
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Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
3599-PPCDT
Funding Award Number
PTDC/BIA-BCM/105602/2008