Ken-ichiro Hayashi, Ph.D

Natural Products Chemistry Lab
Department of Biochemistry

Okayama University of Science 

Contact: E-mail

Department of Biochemistry
Okayama University of Science
1-1 Ridai-cho, Okayama City
700-0005 Japan

Reserach Aera
Chemical Biology
Bioorganic Chemistry
Natural Product Chemsitry

Rserch Subjects

Plant growth and development are regulated by plant hormones, such as auxin, cytokinin, ethylene, ABA and GA,
together with environmental conditions. Indole 3-acetic acid, natural auxin is first identified plant hormone and
crucial role in most aspects of plant growth and development. At the whole plant level, auxin regulates tropisms,
apical dominance, root development, and ultimately
controls the architecture of adult plants.

My final goal of research is to reveal the regulatory mechanism of plant hormone using chemical biological approach.
Chemical Biology is one of the interfacial science, that provide an answer biological questions by directly probing living
systems at the chemical level. Chemical biological studies utilize the small compounds that modulate the biological
process or specifically recognize a certain biological molecule. These small compounds is called bio-probes
and that have been designed for a specific purpose or identified on the basis of biochemical or cell-based screening.
In combination with biochemistry, genetics, or molecular biology, the bio-probes can provide a new insight into
biological systems. My group have been applied the chemical biological approach into plant biological studies.

My group has been investigating the bio-probes specific to plant systems. Yokonolides and terfestatin A are
bio-probes that specifically inhibits auxin signaling using chemical biological approach.
We also designed the caged gene-inducer that can regulate the gene-expression by light.
These probes would be usefull tools for plant biological studies.
Evaluation by plant biologists ; yokonolideterfestatin and caged gene inducers)

         Indole-3-acetic acid (Natural Auxin)

Recently, we found small molecule agonists and antagonist of TIR1 auxin receptor. These probes are auxin
analogues that specifically binds to auxin binding site of TIR1 and perturbes the interaction between TIR1
and Aux/IAA repressors. My group revealed the molecular mechanisum of these TIR1 specifc probes
by crystallographic analsys of TIR1-probe complex and molecular docking calculation.
These probes are effective beyond the model plants Arabidopsis and rice.
The probes inhibited auxin responses in lower land plant, moss physcomitllia patens.
If you interested in new auxin probes, contact to our lab. The probes are free for academic research.

Crystal structure of antiauxin, BH-IAA and TIR1.

Phenotypes treated with probe 8, BH-IAA.
The structure of yokonolide B and terfestatin A


Arabidopsis plants treated with yokonolide B

Selected publications on plant chemical biology   
Full publication list including natural products research )

Rational Design of an Auxin Antagonist of the SCF(TIR1) Auxin Receptor Complex.
Hayashi K, Neve J, Hirose M, Kuboki A, Shimada Y, Kepinski S, Nozaki H.
ACS Chem Biol. 2012 16, 90-8.

Alkoxyauxins are selective inhibitors of auxin transport mediated by PIN, ABCB, and AUX1 transporters.
E. Tsuda, H. Yang, T. Nishimura, Y. Uehara, T. Sakai, M. Furutani, T. Koshiba, M. Hirose, H. Nozaki, A.S. Murphy, K. Hayashi
J. Biol. Chem., 2011, 286, 2354-2364

Endogenous diterpenes derived from entkaurene, a common gibberellin precursor, regulate protonema differentiation of the moss Physcomitrella patens.
K. Hayashi, K. Horie, Y. Hiwatashi, H. Kawaide, S. Yamaguchi, A. Hanada, T. Nakashima, M. Nakajima, L.N. Mander, H. Yamane, M. Hasebe, H. Nozaki
Plant. Physiol., 2010, 153, 1085-1097

ABP1 mediates auxin inhibition of clathrin-dependent endocytosis in Arabidopsis. S. Robert, J. Kleine-Vehn, E. Barbez, M. Sauer, T. Paciorek, P. Baster, S. Vanneste, J. Zhang, S. Simon, M. Covanova,
K. Hayashi, P. Dhonukshe, Z. Yang, S.Y. Bednarek, A.M. Jones, C. Luschnig, F. Aniento, E. Zazimalova, J. Friml
Cell., 2010, 143, 111-121

Kusaka N, Maisch J, Nick P, Hayashi KI, Nozaki H.
Manipulation of Intracellular Auxin in a Single Cell by Light with Esterase-Resistant Caged Auxins.
Chembiochem. 2009, 10(13):2195-2202.  ( Cover Picture and highlightend in Nature Chamical Biology)

K. Hayashi, X. Tan, N. Zheng, T. Hatate, Y. Kimura, S. Kepinski, H. Nozaki
Small molecule agonists and antagonists of F-box protein-substrate interactions in auxin perception and signaling
Proc Natl Acad Sci U S A, 2008, 105(14) 5632-5637