Structure of the class XI myosin globular tail reveals evolutionary hallmarks for cargo recognition in plants

TUROWSKI V.R.*; RUIZ D.M.*; NASCIMENTO A.F.Z.; MILLAN C.; SAMMITO M.D.; JUANHUIX J.; CREMONESI A.S.; USON I.; GIUSEPPE P.O.; MURAKAMI M.T.

ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2021

0907-4449

The plant-specific class XI myosins (MyoXIs) play key roles at the molecular,cellular and tissue levels, engaging diverse adaptor proteins to transport cargoesalong actin filaments. To recognize their cargoes, MyoXIs have a C-terminalglobular tail domain (GTD) that is evolutionarily related to those of class Vmyosins (MyoVs) from animals and fungi. Despite recent advances inunderstanding the functional roles played by MyoXI in plants, the structureof its GTD, and therefore the molecular determinants for cargo selectivity andrecognition, remained elusive. In this study, the first crystal structure of a MyoXIGTD, that of MyoXI-K from Arabidopsis thaliana, was elucidated at 2.35 Aresolution using a low-identity and fragment-based phasing approach inARCIMBOLDO_SHREDDER. The results reveal that both the compositionand the length of the 5?6 loop are distinctive features of MyoXI-K, providingevidence for a structural stabilizing role for this loop, which is otherwise carriedout by a molecular zipper in MyoV GTDs. The crystal structure also shows thatmost of the characterized cargo-binding sites in MyoVs are not conserved inplant MyoXIs, pointing to plant-specific cargo-recognition mechanisms. Notably,the main elements involved in the self-regulation mechanism of MyoVs areconserved in plant MyoXIs, indicating this to be an ancient ancestral trait.