Kiyoshi Nagai was born in Osaka, Japan in 1949. He obtained his B.Sc. and M.Sc. degrees from Osaka University and began working toward his Ph.D. in 1974 under the supervision of Hideki Morimoto. He was inspired by Max Perutz's landmark paper on the allosteric effect of haemoglobin which explains how haemoglobin binds oxygen cooperatively based on its crystal structures.
During his Ph.D. studies he was very fortunate to spend 18 months as a visiting student at the MRC Laboratory of Molecular Biology, Cambridge, and worked with John Kilmartin and Max Perutz. After completing his Ph.D. in Japan, he returned to MRC LMB to work on overproduction of eukaryotic proteins in E. coli and studied the hemoglobin function and evolution by protein engineering by site-directed mutagenesis. In 1987 he became a tenured group leader and began his structural work on DNA and RNA binding proteins. His group determined the crystal structure of many components of the spliceosome as protein or RNA−protein complexes including human U1 snRNP.
In 2000 he was elected a fellow of the Royal Society and a member of EMBO. In 2013 with Wojtek Galej and Andy Newman he determined the structure of Prp8, a key protein which interacts intimately with the catalytic RNA core of the spliceosome. From 2014 his group has applied cryo-EM to capture the structures of the spliceosome in different assembly and catalytic states. The paper by his student Kelly Nguyen (2015) describes the first structure of the large spliceosomal assebly which revealed how the RNA and proteins ssembled in the spliceosome. His group has captured the spliceosome at different states by cryoEM and provided crucial insight into the catalytic mechanism of pre-mRNA splicing. He is a keen amateur cellist and enjoys chamber music.