Chikashi Toyoshima

Chikashi Toyoshima (, Hepburn: ; born July 17, 1954) is a Japanese biophysicist, a professor at the University of Tokyo and a Foreign Associate of the National Academy of Sciences in the United States. His research focuses on two proteins: the Ca2+ ATPase, and the Na+/ K+-ATPase. Toyoshima's research about Ca2+ ATPase started in 1989. He and his colleagues obtained the world's first series of images of Ca2+ ATPase at the atomic level. He has determined the crystal structures of ten intermediates of Ca2+ ATPase via X-ray crystallography, cryogenic electron microscopy (cryo-EM), among other methods. Toyoshima and Poul Nissen were awarded the Gregori Aminoff Prize in 2016 by The Royal Swedish Academy of Sciences for their fundamental contributions to understanding the structural basis for ATP-driven translocation of ions across membranes.

Early life and education

Toyoshima was born in Honjō in the prefecture of Akita, Japan. Toyoshima and his elder brother worked on science experiments at home with their mother. In 1973, he was admitted to the University of Tokyo. He studied regular physics, biochemistry, and botany during his first two years at the university. In the middle of his third year, he visited Setsuro Ebashi's laboratory, which used electron microscopes. He received his undergraduate degree in 1978. For his master's and doctoral research, Toyoshima focused on the microscopy of thin muscle filaments and myosin heads under the supervision of Setsuro Ebashi. Then in 1983, he completed his doctoral degree. He later conducted research on the acetylcholine receptor after studying cryo-EM in Nigel Unwin's laboratory in 1986. There, he developed a new algorithm to untangle the superimposed images obtained from the cryo-EM. In doing so, he reconstructed a 3D structure of an ion channel at 17 Å resolution. This was the first 3D reconstruction of this ion channel.

As of 2023, he has determined the crystal structures of the Ca2+ ATPase in ten different states by X-ray crystallography, covering roughly the entire reaction cycle. He also extended his research to the Na+, K+-ATPase and has developed a methodology for electron crystallography of ultra-thin 3 dimensional protein crystals.

Awards

Asahi Prize, Asahi Shimbun (2009) Yamazaki-Teiichi Prize (2011) Medal with Purple Ribbon (2015) Uehara Prize, The Uehara Memorial Foundation (2015) Gregori Aminoff Prize, The Royal Swedish Academy of Sciences (2016; awarded September 10, 2015) Asian Scientist 100, Asian Scientist, 2019