7dhw | pdb_00007dhw
Crystal structure of myosin-XI motor domain in complex with ADP-ALF4
Structural highlights
FunctionMYO6_ARATH Myosin heavy chain that is required for the cell cycle-regulated transport of various organelles and proteins for their segregation. Functions by binding with its tail domain to receptor proteins on organelles and exerting force with its N-terminal motor domain against actin filaments, thereby transporting its cargo along polarized actin cables. Involved in the tip growth of root hair cells. Plays a major role in trafficking of Golgi stacks, mitochondria and peroxisomes during root hair development. Targets the peroxisome through an interaction with RABC2A. Required for development of pavement cells, trichomes, and stigmatic papillae.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedCytoplasmic streaming with extremely high velocity ( approximately 70 mum s(-1)) occurs in cells of the characean algae (Chara). Because cytoplasmic streaming is caused by myosin XI, it has been suggested that a myosin XI with a velocity of 70 mum s(-1), the fastest myosin measured so far, exists in Chara cells. However, the velocity of the previously cloned Chara corallina myosin XI (CcXI) was about 20 mum s(-1), one-third of the cytoplasmic streaming velocity in Chara Recently, the genome sequence of Chara braunii has been published, revealing that this alga has four myosin XI genes. We cloned these four myosin XI (CbXI-1, 2, 3, and 4) and measured their velocities. While the velocities of CbXI-3 and CbXI-4 motor domains (MDs) were similar to that of CcXI MD, the velocities of CbXI-1 and CbXI-2 MDs were 3.2 times and 2.8 times faster than that of CcXI MD, respectively. The velocity of chimeric CbXI-1, a functional, full-length CbXI-1 construct, was 60 mum s(-1) These results suggest that CbXI-1 and CbXI-2 would be the main contributors to cytoplasmic streaming in Chara cells and show that these myosins are ultrafast myosins with a velocity 10 times faster than fast skeletal muscle myosins in animals. We also report an atomic structure (2.8-A resolution) of myosin XI using X-ray crystallography. Based on this crystal structure and the recently published cryo-electron microscopy structure of acto-myosin XI at low resolution (4.3-A), it appears that the actin-binding region contributes to the fast movement of Chara myosin XI. Mutation experiments of actin-binding surface loops support this hypothesis. Discovery of ultrafast myosin, its amino acid sequence, and structural features.,Haraguchi T, Tamanaha M, Suzuki K, Yoshimura K, Imi T, Tominaga M, Sakayama H, Nishiyama T, Murata T, Ito K Proc Natl Acad Sci U S A. 2022 Feb 22;119(8). pii: 2120962119. doi:, 10.1073/pnas.2120962119. PMID:35173046[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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