The plant-specific class XI myosins (MyoXIs) play key roles at the molecular, cellular and tissue levels, engaging diverse adaptor proteins to transport cargoes along actin filaments. To recognize their cargoes, MyoXIs have a C-terminal globular tail domain (GTD) that is evolutionarily related to those of class V myosins (MyoVs) from animals and fungi. Despite recent advances in understanding the functional roles played by MyoXI in plants, the structure of its GTD, and therefore the molecular determinants for cargo selectivity and recognition, remain elusive. In this study, the first crystal structure of a MyoXI GTD, that of MyoXI-K from Arabidopsis thaliana, was elucidated at 2.35 Å resolution using a low-identity and fragment-based phasing approach in ARCIMBOLDO_SHREDDER. The results reveal that both the composition and the length of the α5-α6 loop are distinctive features of MyoXI-K, providing evidence for a structural stabilizing role for this loop, which is otherwise carried out by a molecular zipper in MyoV GTDs. The crystal structure also shows that most of the characterized cargo-binding sites in MyoVs are not conserved in plant MyoXIs, pointing to plant-specific cargo-recognition mechanisms. Notably, the main elements involved in the self-regulation mechanism of MyoVs are conserved in plant MyoXIs, indicating this to be an ancient ancestral trait.
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http://dx.doi.org/10.1107/S2059798321001583 | DOI Listing |
J Biol Chem
November 2024
Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai, China. Electronic address:
Histones are traditionally recognized for structuring nuclear architecture and regulating gene expression. Recent advances have revealed their roles in inflammation, coagulation, and immune responses, where they act as damage-associated molecular patterns. The mechanisms by which histones induce membrane leakage are not well understood, and certain cells, including endothelial cells and peritoneal macrophages, show resistance to histone-mediated pore formation.
View Article and Find Full Text PDFNat Commun
November 2024
Department of Biology, Massachusetts Institute of Technology, Cambridge, 02139, USA.
AAA+ proteolytic machines unfold proteins before degrading them. Here, we present cryoEM structures of ClpXP-substrate complexes that reveal a postulated but heretofore unseen intermediate in substrate unfolding/degradation. A ClpX hexamer draws natively folded substrates tightly against its axial channel via interactions with a fused C-terminal degron tail and ClpX-RKH loops that flexibly conform to the globular substrate.
View Article and Find Full Text PDFNat Commun
November 2024
Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 34141, South Korea.
Histone post-translational modifications play pivotal roles in eukaryotic gene expression. To date, most studies have focused on modifications in unstructured histone N-terminal tail domains and their binding proteins. However, transcriptional regulation by chromatin-effector proteins that directly recognize modifications in histone globular domains has yet to be clearly demonstrated, despite the richness of their multiple modifications.
View Article and Find Full Text PDFPlant Dis
November 2024
Guangxi University, Agricultural College, 100, Daxue Road Nanning, Guangxi, CN, Nanning, China, 530005;
J Cell Biochem
October 2024
College of Life Science, Northwest A&F University, Yangling, Shaanxi, P.R. China.
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