Unraveling the fastest myosin: Discovery history and structure-function relationships of algae Chara myosin XI

Figures

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  Figure 1. (A) algae Chara (B) Myosin XI binds to the endoplasmic reticulum at the tail and moves on actin filaments, causing cytoplasmic streaming in plant cells. (C) Schematic diagram of the domain structure of myosin XI. From the N-terminal end, a motor domain, six IQ motifs that function as lever arm, and a coiled-coil that forms a dimer, followed by a globular tail domain (GTD) that binds to the endoplasmic reticulum. This domain structure is like that of animal myosin XI. Reproduced with some modifications from Ref. [1].

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  Figure 2. Phylogenetic relationships based on the amino acid sequence of the motor domain of Chara myosins and velocity of each Myosin. Reproduced with some modifications from Ref [1].

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  Figure 3. Velocities various classes of myosins. Green: Chara myosins, yellow: Arabidopsis myosins, magenta: animal myosins. Reproduced with some modifications from Ref. [1].

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  Figure 4. Actin-binding region with high amino acid diversity among myosins. (A) Docking model of AtXI-2 MD and actin. (B) Heat map visualization of AtXI-2 MD showing amino acid conservation and diversity. Reproduced with some modifications from Ref. [1].

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  Figure 5. Interaction of CM loop and loop 4 of various myosins with actin. The interactions of MDs (white) of CbXI-1 (A, homology model built using PDB ID: 7KCH), CcXI (B, PDB ID: 7KCH), NM2c (C, PDB ID: 5JLH), Myo6 (D, PDB ID: 6BNP), Myo1b (E, PDB ID: 6C1H), Pf MyoA (F, PDB ID: 7ALN) and actin (light orange) are shown as ribbon and surface representations. The residues in the actin, CM loop, and loop 4 within 4 Å between the actin and myosin are colored in orange, magenta, and blue. The surface model represents actin, and the ribbon model represents myosin. Reproduced with some modifications from Ref. [1].

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  Figure 6. Enzymatic properties of the four classes of myosins: (A) Velocities; (B) ADP dissociation rate from myosin when bound to actin; (C) ADP dissociation rate from myosin when not bound to actin; (D) Acceleration of ADP release by actin. CcXI: Chara corallina myosin XI, Rb FsKII: Rabbit fast skeletal muscle myosin II, Chick V: Chicken myosin V, Pig: Pig myosin VI. Data from Ref. [3].