SPring-8, the large synchrotron radiation facility

Release Date

27 Nov, 2008

Key research achievements
- Determination of the molecular structure of the receptor of the signaling molecule "gibberellin", a plant hormone, for the first time
- Clarification of the mechanism underlying the molecular recognition of gibberellin by its receptor and the molecular evolution of the receptor
- Hopes for an increase in food production by the development of a technology that completely regulates plant height

Nagoya University (Shinichi Hirano, President) and Kyoto University (Hiroshi Matsumoto, President) first clarified the three-dimensional structure of the receptor of the plant hormone gibberellin.  This is the achievement of the research group of Makoto Matsuoka, professor in the Bioscience and Biotechnology Center, Nagoya University; Hiroaki Kato, professor in the Graduate School of Pharmaceutical Sciences, Kyoto University; and other researchers.  With the support of the Target Protein Research Program of the Ministry of Education, Culture, Sports, Science and Technology, they carried out an X-ray analysis of the crystal structure using SPring-8 and obtained results through collaboration with the research groups of the University of Tokyo (Hiroshi Komiyama, President) and RIKEN (Ryoji Noyori, President).  

Plant growth is controlled by the growth hormone gibberellin.  Plants grow too high and fall over when gibberellin functions excessively, and they become short when gibberellin is deficient.  Gibberellin affects plants because a protein receptor recognizes it and transmits the signal to the cells, resulting in their cell division and extension.

The key point of this research is that, using rice as a test subject, it was clarified how the gibberellin receptor (called GID1) binds to gibberellin and transmits the information that it has bound to gibberellin to cells.  Strangely, GID1 closely resembles lipase, which exists widely in all organisms including microorganisms, animals, and plants.  However, why GID1, which resembles lipase, recognizes and binds to gibberellin has been a complete mystery.  This research clarified that the gibberellin receptor is formed by the replacement of the most important site (active site) of lipase with the binding site for gibberellin.  Moreover, although the origin of the receptor dates back to the time of the appearance of ferns (about four hundred million years ago) after the appearance of moss (about four hundred and thirty million years ago), the GID1 receptor in ferns is greatly inferior to that of rice, a more advanced plant, in terms of its ability to recognize and bind gibberellin.  Therefore, it was revealed that plants have acquired a mechanism to more ingeniously control their growth by improving GID1 function through evolution.

Gibberellin is a very important hormone in agriculture.  During the spread of the "Green Revolution" in the latter half of the 20th century, people succeeded in doubling the yield of rice and wheat by changing the amount of and sensitivity to gibberellin in them.  Since this study clarified how the gibberellin receptor in rice binds to gibberellin, it is now possible to generate a receptor that more easily bind to gibberellin as well as a receptor that binds poorly to gibberellin.  This means that the growth of rice can be completely controlled, and this finding is expected to become a spark for the "Second Green Revolution."

This research achievement was published in Nature on 27 November 2008.

Publication:
"Structural basis for gibberellin recognition by its receptor GID1"
Asako Shimada, Miyako Ueguchi-Tanaka, Toru Nakatsu, Masatoshi Nakajima, Youichi Naoe, Hiroko Ohmiya, Hiroaki Kato & Makoto Matsuoka
Nature 456, 520-523 (2008), published online 27 November 2008

The crystal structures of gibberellin receptor (left) and lipase (right).