8glv
96-nm repeat unit of doublet microtubules from Chlamydomonas reinhardtii flagella
Structural highlights
FunctionTBB_CHLRE Tubulin is the major constituent of microtubules. It binds two moles of GTP, one at an exchangeable site on the beta chain and one at a non-exchangeable site on the alpha chain. Publication Abstract from PubMedMotile cilia and flagella beat rhythmically on the surface of cells to power the flow of fluid and to enable spermatozoa and unicellular eukaryotes to swim. In humans, defective ciliary motility can lead to male infertility and a congenital disorder called primary ciliary dyskinesia (PCD), in which impaired clearance of mucus by the cilia causes chronic respiratory infections(1). Ciliary movement is generated by the axoneme, a molecular machine consisting of microtubules, ATP-powered dynein motors and regulatory complexes(2). The size and complexity of the axoneme has so far prevented the development of an atomic model, hindering efforts to understand how it functions. Here we capitalize on recent developments in artificial intelligence-enabled structure prediction and cryo-electron microscopy (cryo-EM) to determine the structure of the 96-nm modular repeats of axonemes from the flagella of the alga Chlamydomonas reinhardtii and human respiratory cilia. Our atomic models provide insights into the conservation and specialization of axonemes, the interconnectivity between dyneins and their regulators, and the mechanisms that maintain axonemal periodicity. Correlated conformational changes in mechanoregulatory complexes with their associated axonemal dynein motors provide a mechanism for the long-hypothesized mechanotransduction pathway to regulate ciliary motility. Structures of respiratory-cilia doublet microtubules from four individuals with PCD reveal how the loss of individual docking factors can selectively eradicate periodically repeating structures. Axonemal structures reveal mechanoregulatory and disease mechanisms.,Walton T, Gui M, Velkova S, Fassad MR, Hirst RA, Haarman E, O'Callaghan C, Bottier M, Burgoyne T, Mitchison HM, Brown A Nature. 2023 Jun;618(7965):625-633. doi: 10.1038/s41586-023-06140-2. Epub 2023 , May 31. PMID:37258679[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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