Poster: Lipids & Related Molecules

Abs # 856: Use of transgenic plants producing poly[(R)-3-Hydroxyalkanoate] for monitoring short-chain-length intermediates of b-oxidation.

Presenter:	Arai, Yuko , yarai@postman.riken.go.jp
Authors	Arai, Yuko  (A) (B)  Nakashita, Hideo  (A)   Kondo, Maki  (B)   Mano, Shoji  (B)   Taguchi, Kazunori  (A)   Nishimura, Mikio  (B)   Doi, Yoshiharu  (A)
Affiliations:	(A): RIKEN Institute (B): National Institute for Basic Biology

Poly[(R)-3-hydroxyalkanoate] (PHA) is a biodegradable polyester produced by various microorganisms. However, it cannot be degraded and accumulates in tissues when produced in a transgenic plant. Therefore, the monomer composition of PHA produced in plant peroxisomes reflects both the relative quantity and quality of (R)-3-hydroxyacyl-CoA flow through b-oxidation pathway. We made use of short-chain-length (SCL)- PHA production system for investigating the metabolisms of SCL-(R)-3-hydroxyacyl-CoA in plant cells. SCL-PHA synthase gene (phaC_Ac) from Aeromonas caviae FA440 was modified by adding a peroxisome targeting signal sequence and introduced into Arabidopsis plants. The localization of PhaC_Ac protein in the peroxisomes was conformed by immunoelectron microscopy. Gas chromatography-mass spectrometry analysis demonstrated that the transgenic plants accumulated a novel type of PHA terpolymer, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate). To examine the correlation between b-oxidation activity and PHA synthesis, the accumulation of SCL-PHA was analyzed at different growth stages. The highest amount of SCL-PHA was accumulated in the senesced leaves. At the germination stage, SCL-PHA accumulation of the transgenic plant was higher in those grown in the dark than in the light. Culturing the transgenic plants in a liquid medium containing Tween-20, a strong inducer of b-oxidation, resulted in an increase in the SCL-PHA accumulation. These results suggested that PHA production in plant peroxisomes is useful to clarify the SCL-fatty acid metabolism at the metabolite level.