SUNTORY INSTITUTE FOR BIOORGANIC RESEARCH

Oct.2007

Research Summary

Having completed the sequencing of the genome of numerous species of animals and plants, including the human genome, we enter the dawn of the post genome era. Today, clarification of the integrated functions of a variety of primary gene products (such as proteins) and/or secondary bioactive substances has become important in order to address the issues on ‘what is the origins of life?’ and ‘how common and unique are biological events?’. Our goal is to comprehensively understand biological events and the evolution and diversity of organisms as ‘multi-dimensional network’ composed of bioactivities of various biological molecules, thereby leading to scientific advance and industrial application. Based on these concepts, we work on the three major projects at the molecular level through the level of the individuals by multiple combinations of various experimental procedures for molecular biology, plant physiology, endocrinology, histochemistry and analytical chemistry.

Major Research Projects

1) Elucidation and application of the functional nervous and endocrine systems of a protochordate, Ciona intestinalis

The ascidian Ciona intestinalis belongs to protochordates, which share a common ancestry with vertebrates including mammals. Ciona intestinalis is believed to possess the prototypes of our nervous and endocrine systems. Indeed, in our earlier studies, prototypes of major neuropeptides and hormones (such as tachykinin and calcitonin) that were not found in any other invertebrate species, were identified in Ciona intestinalis.

Our current research aims at elucidating the functional network of the nervous and endocrine systems of Ciona intestinalis, and at verifying the evolutionary process of nervous and endocrine functions in chordates. Furthermore, we have been attempting to establish Ciona intestinalis as a novel and simple model organism for studies on the human nervous and endocrine systems, which is expected to dramatically enhance the development of new functional foods and pharmaceutical products.

1. Neuropeptides, hormones, and their receptors in ascidians - Emerging model animals.
   Satake, H. and Kawada H.
   “Invertebrate Neuropeptides and Hormones: Basic Knowledge and Recent Advances”,
   253-276, ed. Satake, H.
   Transworld Research Network, Kerala, India (2006).
2. A novel biological role of tachykinins as an upregulator of oocyte growth: identification of an evolutionary origin of tachykinergic functions in the ovary of the ascidian, Ciona intestinalis”
   Aoyama, M., Kawada, T., Fujie, M., Hotta, K., Sakai, T., Sekiguchi, T., Oka, K., Satoh, N., Satake, H.
   Endocrinology, in press

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2) Structure and function of transporter for phytosiderophore-iron complex

Graminaceous plants secrete phytosiderophore, mugineic acids, as one of its secondary metabolites. These plants have uptake systems for metal ion complexes with mugineic acids. We identified a specific transporter for phytosiderophore-ferric iron complexes in barley and found the structural elements responsible for substrate specificity.

This project focuses on the verification of the iron acquisition mechanism and structure of the transporter for mugineic acids-iron complexes. We consider the potential application of this transporter to cereal crops and other useful plants to produce transgenic plants that enhanced tolerance to iron deficiency stress in alkaline soils, which account for approximately 30% of the world’s cultivated soils. Our project provides crucial clues to the exploration of new biomass sources and to resolution of the World Food Problem.

1. Structural element responsible for the Fe(III)-phytosiderophore specific transport by HvYS1 transporter in barley.
   Harada, E., Sugase, K., Namba, K., Iwashita, T., and Murata, Y.
   FEBS Lett. 581 (22), 4298-4302 (2007).
2. A practical synthesis of the phytosiderophore 2'-deoxymugineic acid: a key to the mechanistic study of iron acquisition by graminaceous plants.
   Namba, K., Murata, Y., Horikawa, M., Iwashita, T., and Kusumoto S.
   Angew. Chem. Int. Ed. 46 (37), 7060-7063 (2007).

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3) Development of transgenic plants for efficient production of useful plant compounds in closed systems: A national project

Agricultural production in a “closed-system plant-factory” is extremely attractive, given that such a system is predicted to be unaffected by environmental conditions, and thus, to provide more efficient and stable productivities than traditional agriculture. We have been (1) developing the transgenic plants competent in production of a useful compound ‘sesamin’ (derived from sesame seeds) by stable transfection of the sesamin synthase gene into the plants containing large amounts of sesamin precursors (e.g., forsythia), and (2) establishing the hydroponic technology-based “closed-system plant-factory” employing an artificial supporting base, which enables efficient growth and abundant supply of the transgenic plants.

1. Formation of two methylenedioxy bridges by a “Sesamum CYP81Q protein yielding a furofuran lignan, (+)-sesamin.
   Ono, E., Nakai, M., Fukui, Y., Tomimori, N., Fukuchi-Mizutani, M., Saito, M., Satake, H., Tanaka, T., Katsuta, M., Umezawa, T., andTanaka, Y.
   Proc. Natl. Acad. Sci. U.S.A. 103 (26), 10116-10121.
2. Sequential glucosylation of a furofuran lignan, (+)-sesaminol, by Sesamum indicum UGT71A9 and UGT94D1 glucosyltransferases”
   Noguchi, A., Fukui, Y., Iuchi-Okada, A., Kakutani, S., Satake, H., Iwashita, T., Nakao, M., Umezawa, T., Ono, E.
   Plant J. 54(3), 415-427 (2008)