JEOL YOKOGUSHI Research Alliance Laboratories

The Namba Lab

Graduate School of Frontier Biosciences - Keiichi Namba

Research


Development of structural biosciences by electron cryomicroscopy

Our group aims to understand the mechanisms of force generation and energy transduction by biological macromolecular motor complexes as well as their self-assembly and regulatory switching. By combining complementary techniques, such as X-ray crystallography and electron cryomicroscopy for high-resolution structural analysis and nanophotometry of individual molecular complexes for analyzing their dynamic behaviors, we are keen to reveal the basic principles behind their functional mechanisms, in the hope that they will become the design basis for highly energy-efficient nanodevices and nanotechnology.

I have been interested in motor proteins since my PhD study as to how they convert chemical or physical energy to mechanical work. When I was a graduate student I strongly felt that fine structures of motor proteins must be revealed at different steps of force generation processes. I decided to study the structure of muscle thin filament in complex with myosin head by X-ray fiber diffraction analysis and was able to obtain some interesting structural information, but it was frustrating that the resolution was limited. During my PhD study, I was also introduced to the rotary motor and helical propeller of the bacterial flagellum that many bacteria use to swim through viscous liquid environment.

Since then our group has been trying to develop various methods for high-resolution structural analysis of large protein complexes by X-ray diffraction and electron microscopy and for high-resolution measurement of rotation dynamics of the flagellar motor by optical nanophotometry. With recent advances in optics and CMOS image sensors in both electron and light microscopy, the spatial and temporal resolutions of the measurements became high enough for us to gain deep enough insights into the mechanisms of those motor systems. We are now beginning to understand how the random Brownian motions of molecules can be biased by their asymmetric structures and interactions to produce directional motions of the motors to achieve extremely high efficiency in energy transduction.


Keiichi Namba
SA Professor

Keiichi Namba obtained his PhD degree from the Graduate School of Engineering Science, Osaka University in 1980, based on X-ray fiber diffraction analysis of the actomyosin structures in skeletal muscle. After spending 5 years in the USA as a postdoctoral research associate, he became Group Leader of ERATO Hotani Dynamic Molecular Assembly Project (JST) in 1986, Research Director of the International Institute for Advance Research of Panasonic in 1992, and Professor of the Graduate School of Frontier Biosciences of Osaka University in 2002. He is now Specially Appointed Professor since 2017 after his retirement. His group aims to understand the mechanisms of self-assembly, force generation and energy transduction by biological macromolecular motors. By using complementary techniques, such as X-ray diffraction and electron cryomicroscopy for structural analysis and nanophotometry on dynamic behaviors of individual motor complexes, his group is beginning to reveal the basic principles behind their functions, in the hope that they will become a basis for artificial nanomachine design and nanotechnology.