8j07
96nm repeat of human respiratory doublet microtubule and associated axonemal complexes
Structural highlights
DiseaseDRC4_HUMAN Primary ciliary dyskinesia. The disease is caused by variants affecting the gene represented in this entry. FunctionDRC4_HUMAN Component of the nexin-dynein regulatory complex (N-DRC), a key regulator of ciliary/flagellar motility which maintains the alignment and integrity of the distal axoneme and regulates microtubule sliding in motile axonemes. Plays an important role in the assembly of the N-DRC linker (By similarity). Plays dual roles at both the primary (or non-motile) cilia to regulate hedgehog signaling and in motile cilia to coordinate cilia movement. Required for proper motile cilia functioning (PubMed:26387594, PubMed:27120127, PubMed:27472056). Positively regulates ciliary smoothened (SMO)-dependent Hedgehog (Hh) signaling pathway by facilitating the trafficking of SMO into the cilium and the stimulation of SMO activity in a GRK2-dependent manner (By similarity).[UniProtKB:Q60779][UniProtKB:Q7XJ96][1] [2] [3] 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[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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