7n32
protofilaments of microtubule doublets bound to outer-arm dyneinprotofilaments of microtubule doublets bound to outer-arm dynein
Structural highlights
FunctionTBA_TETTH 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 PubMedThousands of outer-arm dyneins (OADs) are arrayed in the axoneme to drive a rhythmic ciliary beat. Coordination among multiple OADs is essential for generating mechanical forces to bend microtubule doublets (MTDs). Using electron microscopy, we determined high-resolution structures of Tetrahymena thermophila OAD arrays bound to MTDs in two different states. OAD preferentially binds to MTD protofilaments with a pattern resembling the native tracks for its distinct microtubule-binding domains. Upon MTD binding, free OADs are induced to adopt a stable parallel conformation, primed for array formation. Extensive tail-to-head (TTH) interactions between OADs are observed, which need to be broken for ATP turnover by the dynein motor. We propose that OADs in an array sequentially hydrolyze ATP to slide the MTDs. ATP hydrolysis in turn relaxes the TTH interfaces to effect free nucleotide cycles of downstream OADs. These findings lead to a model explaining how conformational changes in the axoneme produce coordinated action of dyneins. Structures of outer-arm dynein array on microtubule doublet reveal a motor coordination mechanism.,Rao Q, Han L, Wang Y, Chai P, Kuo YW, Yang R, Hu F, Yang Y, Howard J, Zhang K Nat Struct Mol Biol. 2021 Oct;28(10):799-810. doi: 10.1038/s41594-021-00656-9. , Epub 2021 Sep 23. PMID:34556869[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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