Poster: Organelle Biogenesis

Abs # 1134: Proteomic analysis of the peroxisomal proteins in cotyledons of Arabidopsis thaliana

Presenter:	Fukao, Youichiro , fukao@nibb.ac.jp
Authors	Fukao, Youichiro  (A)   Hayashi, Makoto  (A)   Hara-Nishimura, Ikuko  (C)   Nishimura, Mikio  (A) (B)
Affiliations:	(A): National Institute for Basic Biology (B): Graduate University for Advanced Studies (C): Kyoto University

In higher plants, glyoxysomes and leaf peroxisomes are present in etiolated and green cotyledons of fatty seedlings, respectively. Glyoxysomes contain enzymes for the metabolism of lipids (the fatty acid b-oxidation cycle and the glyoxylate cycle), whereas leaf peroxisomes contain enzymes for the photorespiration pathway (the glycolate pathway). Peroxisomes are directly transformed from glyoxysomes to leaf peroxisomes in cotyledons. Recently, the complete genome sequences of Arabidopsis were determined, and 25,498 genes were annotated in the genome. It is deduced from the genome search that 281 genes for proteins with peroxisomal targeting signals (PTS1 and PTS2) or proteins related to the functions of peroxisomes are present in the Arabidopsis genome. Since only a few genes were identified functionally among them, there seems to be many functionally unknown peroxisomal proteins in Arabidopsis. We report here a method for isolating peroxisomes from Arabidopsis cotyledons in high purity and the proteomic analysis of glyoxysomal and leaf peroxisomal proteins. We identified 19 glyoxysomal proteins including 13 novel proteins in the glyoxysomal proteomic analysis and 29 leaf peroxisomal proteins including 19 novel proteins in the leaf peroxisomal proteomic analysis by MALDI-TOF MS. Then, we further analyzed a serine/threonine protein kinase-like protein identified as one of the novel glyoxysomal proteins.