Discovery of the fastest myosin in the biological world – Waseda University


Successfully discovered the fastest myosin in the biological world and analyzed its structure
Promising to boost plant growth and develop nanomachines


The protein “myosin” that exists in living organisms is the driving force for various movements of animals and plants. Chiba University Graduate School of Science (concurrently serving as Membrane Protein Research Center, Molecular Activity Research Center, Plant Molecular Science Research Center) Professor Koji Ito, Professor Takeshi Murata, etc. cooperate with research groups from Waseda University, Kobe University and Kanazawa University. The fastest Myosin gene (Shajikumo myosin)CBI found XI-1). In addition, the fastest myosin class, myosin XI (Arabidopsis myosin)existWe have successfully performed the world’s first high-resolution crystal structure analysis XI-2).getexistThe fastest myosin with 3D structural information for XI-2CBWhen we created a three-dimensional structural model of XI-1, we revealed that the secret of the fastest myosin lies in the binding region to actin.

As a result, we can expect to increase the scale of resource plants, such as crops that are plants necessary for our daily life, and to grow plants efficiently.

The research results were published in the American scientific journal Proceedings of the National Academy of Sciences on February 22, 2022 (February 21, Japan time).

◆ Research Background

Myosin is a typical motor protein that converts the chemical energy generated by the hydrolysis of ATP (adenosine triphosphate), which is ubiquitous in eukaryotes, into kinetic energy for movement along actin fibers.Note 1)About 80 years ago, it was discovered to be a protein that causes muscle contractions in animals. Myosins are present in almost all eukaryotes, including plants and animals, and are a superfamily that can be divided into 79 classes according to their amino acid sequences.Note 2)configured.

In the cells of plants and algae, an intracellular flow called cytoplasmic flow occurs. This is thought to be because the cells of plants and algae, whose cells are several to several thousand times larger than animal cells, efficiently distribute oxygen and nutrients absorbed from outside the cells throughout the cell (Fig. 1a). Cytoplasmic flow is caused by the hydrodynamic effects of myosin class XI (myosin XI) binding to organelles, such as the endoplasmic reticulum that moves along actin fibers (Fig. 1b). The flow rate is thought to be equal to myosin XI in the plants and algae that cause it.

For more than 50 years, freshwater algae Charales have had cell sizes on the order of centimeters and the fastest cytoplasmic flow rates.Chara coral, Chara braunii), predicted to be the fastest ultrafast myosin in the living world based on its cytoplasmic flow rate, 10 times faster than angiosperm myosin XI.

The research team previously used angiosperm myosin XI as chara braunii (Chara Coral) CcXI of myosin XI (myosin XI, which is three times the rate of angiosperm myosin XI), when replaced by molecular biology techniques, the size of the plant increases with the rate of cytoplasmic flow.Note 3)..however, the substance of ultrafast myosin 10 times faster is a mystery. If the molecular mechanisms that enable ultrafast myosin gene segregation and ultrafast movement are elucidated, it can be expected that plants will grow through increased cytoplasmic flow rates of resource plants (Fig. 1c).

◆ Research results

The research was recently conducted by Assistant Professor Nishiyama at Kanazawa University and Associate Professor Sakayama at Kobe University.beet) (Fig. 2a) Genome decodingNote 4)The four predicted myosin XI genes were isolated fromCBI named them XI-1, 2, 3 and 4. When a phylogenetic tree was created from the amino acid sequences of these four motor regions, it was divided into two subgroups, the previously reported 24 µm/s Chara braunii (Chara Coral)ofccXINote 5)belongs to subclass 2CBXI-4 orthologNote 6)The result is (Fig. 2b).

Thus, these four myosin XIs were expressed in cultured insect cells, purified, and then vitroexercise testNote 7)Subclass 1 when measuring the speed of motion of motor actin fibersCBwith XI-1CBXI-2 is an ultrafast myosin of about 70 µm/s.CBXI-1 was found to be the fastest myosin in the living world with a velocity of 73 µm/s (Fig. 2c).

Furthermore, as the first crystal structure analysis of myosin XI, Arabidopsis myosinexistHigh-resolution structural analysis of XI-2 was successfully performed.getexist3D structural information from XI-2CBI made a 3D structural model of the XI-1.From this 3D structural model and gene mutation experimentsCBWe revealed that the secret of XI-1’s superluminal motion lies in its mode of binding to actin fibers (Fig. 2d).

◆ Future Outlook

The fastest ultrafast myosin discovered in the biological worldCBThe XI-1 gene is expected to be used to increase the yield of resource plants, and if food production is increased by expanding the size of plants, it is expected to cope with food shortages and population growth caused by natural disasters. In addition, by using the ultra-high-speed myosin XI gene, we can expect to develop nanomachines for ultra-high-speed motion.

◆ Research Grants

This research was supported by JPPS Kakenhi JP 20K06583, 17K07436, 15H01309 (Koji Ito), 18H05425 (Takeshi Murata), 15K07185, 16H05764, 18K06382 (Hidetoshi Sakayama), 15H04413 (Motoki Tominaga), JST 401 AL Tominaga) BINDS JP20am0101083 (Takeshi Murata).

◆ Explanation of words and phrases

Note 1) Kinesin
A protein that utilizes the energy of ATP hydrolysis for exercise. There are myosin, dynein, and kinesin as motor proteins for translational motion, and F-type ATPases and V-type ATPases as motor proteins for rotational motion.

Note 2) Myosin superfamily
A group of proteins derived from a common evolutionary ancestor and having the same domains and motifs is called a superfamily. The myosin superfamily consists of 79 myosin classes. Myosin classes are written in Roman numerals. Different classes of myosin have markedly different myosin properties, such as kinetic rate and ATP hydrolysis activity. Furthermore, even within the same class, different species of organisms have different myosin properties.

Note 3) Cytoplasmic flow velocity as a determinant of plant size.

Note4)This Chara Genomes: secondary complexity and implications for plant terrestrialization.

Note5) kinetic mechanisms of the fastest motor proteins, Chara myosin*

Note 6) Ortholog
A set of genes is separated from a gene and a corresponding gene from a common ancestor in two different organisms with speciation.

Note 7)in vitroexercise test
A method for observing, recording, and analyzing the motion of fluorescently labeled actin fibers driven by myosin immobilized on a coverslip using a fluorescence microscope, and measuring the speed of myosin-driven actin fiber motion.

◆ Moderator

Takeshi Haraguchi* (Researcher, Graduate School of Chiba University)
Masanori Tamanaha* (PhD student, Graduate School of Integrated Science and Engineering, Chiba University)
Hanano Suzuki* (Researcher, Graduate School of Chiba University)
Kohei Yoshimura (PhD student, Graduate School of Integrated Engineering, Chiba University)
Takuma Imi (Master student at the Graduate School of Integrated Engineering, Chiba University)
Motoki Tominaga (Associate Professor, Faculty of Education, Waseda University)
Hidetoshi Sakayama (Associate Professor, Kobe University Graduate School)
Tomoaki Nishiyama (Assistant Professor, Center for Disease Modeling Research, Kanazawa University)
Murata Ken+ (Professor, Graduate School of Science, Chiba University)
Koji Ito+(Professor, Graduate School of Science, Chiba University)

(* first author, + responsible author)

◆ Thesis materials

タイトル: Discovery of ultrafast myosin, its amino acid sequence and structural features
Authors: Takeshi Haraguchi, Masanori Tamanaha, Kano Suzuki, Kohei Yoshimura, Takuma Imi, Motoki Tominaga, Hidetoshi Sakayama, Tomoaki Nishiyama, Takeshi Murata and Kohji Ito
Magazine: Process. National Oil Company. Academic school. science.America

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