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Publication Abstract from PubMed

The motor protein myosin-15 is necessary for the development and maintenance of mechanosensory stereocilia, and mutations in myosin-15 cause hereditary deafness. In addition to transporting actin regulatory machinery to stereocilia tips, myosin-15 directly nucleates actin filament ("F-actin") assembly, which is disrupted by a progressive hearing loss mutation (p.D1647G, "jordan"). Here, we present cryo-electron microscopy structures of myosin-15 bound to F-actin, providing a framework for interpreting the impacts of deafness mutations on motor activity and actin nucleation. Rigor myosin-15 evokes conformational changes in F-actin yet maintains flexibility in actin's D-loop, which mediates inter-subunit contacts, while the jordan mutant locks the D-loop in a single conformation. Adenosine diphosphate-bound myosin-15 also locks the D-loop, which correspondingly blunts actin-polymerization stimulation. We propose myosin-15 enhances polymerization by bridging actin protomers, regulating nucleation efficiency by modulating actin's structural plasticity in a myosin nucleotide state-dependent manner. This tunable regulation of actin polymerization could be harnessed to precisely control stereocilium height.

Structural basis for tunable control of actin dynamics by myosin-15 in mechanosensory stereocilia.,Gong R, Jiang F, Moreland ZG, Reynolds MJ, de Los Reyes SE, Gurel P, Shams A, Heidings JB, Bowl MR, Bird JE, Alushin GM Sci Adv. 2022 Jul 22;8(29):eabl4733. doi: 10.1126/sciadv.abl4733. Epub 2022 Jul, 20. PMID:35857845^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.