Poster: Posttranscriptional Regulation

Abs # 1076: Regulation of the alternative splicing of chloroplast ascorbate peroxidase pre-mRNA by a cis-element/SRE

Presenter:	Yoshimura, Kazuya , yosimura@nara.kindai.ac.jp
Authors	Yoshimura, Kazuya  (A)   Yamada, Satoshi  (B)   Tanabe, Noriaki  (B)   Fujiwara, Noriki  (B)   Ishikawa, Takahiro  (C)   Shigeoka, Shigeru  (A) (B)
Affiliations:	(A): Department of Food and Nutrition, Faculty of Agriculture, Kinki University (B): Advanced life Science, Graduate School Kinki University (C): Faculty of Life and Environmental Science, Shimane University

Alternative splicing events in the 3'-terminal region of chloroplast ascorbate peroxidase (chlAPX) pre-mRNA in spinach and tobacco produce four types of mRNA variants, one form (tAPX-I) encoding thylakoid-bound APX (tAPX) and three forms (sAPX-I, -II, -III) encoding stromal APX (sAPX). The levels of sAPX-III and tAPX-I resulting from the alternative excision of intron 11 and intron 12, respectively, were regulated with tissue specific manner by the splicing regulatory cis-element (SRE) located on the upstream of acceptor site in intron 12 (Yoshimura et al., 2002 J. Biol. Chem., 277, 40623-40632). Here we investigated the possibility that the regulation of alternative splicing by SRE is a general mechanism in higher plants. The truncated 3'-terminal regions of spinach chlAPX gene placed under the control of CaMV 35S promoter were transformed to Arabidopsis plants which have been found to contain two independent genes for chlAPX isoenzymes. Interestingly, all four types of alternatively spliced mRNAs derived from the transgene were detected in the transformed Arabidopsis. In contrast, the deletion of the SRE sequence diminished the splicing efficiency of intron 12. These results suggest that the SRE regulates the other alternative splicing events in Arabidopsis. Serine-arginine rich (SR) proteins have been known to play a role in the regulation of alternative splicing as a trans-acting factor in vertebrates. We cloned SR proteins from Arabidopsis and analyzed the interaction between SRE sequence and SR proteins by the yeast Three Hybrid system. As a result, 6 types of SR proteins had a potential to bind to the SRE sequence. Now, we are currently generating the transgenic plants overexpressing those SR proteins.