Poster: Organelle Biogenesis

Abs # 1164: Analysis of the Tic40 component of the plastid protein import machinery in Arabidopsis

Presenter:	Niwa, Yasuo , niwa@u-shizuoka-ken.ac.jp
Authors	Niwa, Yasuo  (A)   Moriyasu, Yuji  (A)   Kajiwara, Hideyuki  (B)   Kato, Tomohiko  (C)   Tabata, Satoshi  (C)   Shirano, Yumiko  (D) (E)  Hayashi, Hiroaki  (F)   Shibata, Daisuke  (D) (C)  Seki, Motoaki  (G)   Kobayashi, Masatomo  (G)   Shinozaki, Kazuo  (G)
Affiliations:	(A): University of Shizuoka (B): Natl. Inst. Agrobiol. Resour. (C): Kazusa DNA Res. Inst. (D): Mitsui Plant Biotech. Res. Inst. (E): Cornell Univ. (F): Univ. Tokyo (G): Riken

Plastids perform a number of essential biochemical functions such as photosynthesis, fatty acid and amino acid biosynthesis. Since most plastid proteins are encoded in the nucleus, they are synthesized as precursor proteins and imported into plastids by pre-protein translocases. The translocon at the outer membrane of chloroplasts (Toc complex) and the translocon at the inner membrane of chloroplasts (Tic complex) act co-operatively during the import process. Putative components of the import apparatus have been identified biochemically using isolated pea (Pisum sativum) chloroplasts. With the completion of the Arabidopsis genome sequencing project, it is now possible to identify putative homologs of the import components in this species. The Arabidopsis homolog of pea Tic40 has been identified and the sub-cellular localization of the AtTic40 has been determined using a GFP reporter gene. Arabidopsis mutants lacking the AtTic40 component have been isolated. The AtTic40 mutant has a pale green phenotype throughout its life-cycle. Morphological and biochemical data demonstrate the effects of the translocon mutation on chloroplast biogenesis.