OHKI Laboratory
<Major Research Areas>Protein NMR, structural biology, biophysics

NMR-based Structural Biology

Research activity

　　The bodies of living creatures are made up of proteins, lipids, and various other molecules. Protein, of which there are said to be 30 to 100 thousand kinds, has a particularly wide range of functions in living things, but little is known about it. For instance, we cannot give an adequate explanation of how the muscles and organs in our bodies work. To answer such questions, we must thoroughly investigate the conformation and properties of each protein and integrate the research results obtained. That would enable us to understand the mechanisms that maintain living creatures, including human beings, and would provide us with clues for the development of new methods of medical care and the design of micro machines powered by low energy.
　　Our laboratory studies the structure-function relationship of proteins using the nuclear magnetic resonance (NMR). The research is mainly focused on certain kinds of proteins related to signal transduction. Specifically, we are investigating the proteins in smooth muscle, metal binding proteins, and motor proteins. We have succeeded in determining the three-dimensional structure of a phosphor protein and the conformational transition process induced by phosphorylation. We have also observed the effect of aluminum ions on the functions of a calcium-binding protein. We are currently investigating a protein phosphatase and motor proteins in cooperation with several other laboratories in Japan and overseas.
　　There are only two analytical methods for the protein structures: NMR and X-ray. The NMR method is particularly advantageous, because it can be used to observe samples in solution without crystallization and while adding reacting substances. We are also engaged in the development of a new measuring technology in NMR, and developing a new sample preparation method using stable isotopes (13C or 15N) for multidimensional NMR.

Equipment

750MHz-NMR, CD spectrometer, SPR, Unix/Linux workstations

The main research achievements in the past five years

1. N. Isozumi, and S. Ohki, Expression and Purification of mGLuR7 peptide, Protein Exp. Purif. 73, 46-50. (2010).
2. S. Mori, R. Iwaoka, M. Eto, and S. Ohki, Solution structure of the inhibitory phosphorylation domain of myosin phosphatase targeting subunit 1, Proteins, 77, 732-735 (2009).
3. S. Ohki, and M. Kainosho, Stable-isotope labeling for protein NMR, Prog. in NMR Spectrosc., 53, 208-226 (2008)
4. S. Ohki, K. Dohi, A. Tamai, M. Takeuchi, and M. Mori, Stable-isotope labeling using an inducible virus vector and suspension cultured plant cells, J. Biomol. NMR, 42, 271-277 (2008).
5. M. Eto, T. Kitazawa, F. Matsuzawa, S. Aikawa, J. A. Kirkbride, N. Isozumi, Y. Nishimura, D. L. Brautigan, and S. Ohki, Phosphorylation-induced conformational switching of CPI-17 produces a potent myosin phosphatase inhibitor, Structure, 15, 1591-1602 (2007).