A Novel Arabidopsis Gene Causes Bax-like Lethality in Saccharomyces cerevisiae

Masaaki Umeda,Hirofumi Uchimiya,Kyung-Min Kim,Yusuke Saito,Taro Ogawa,Maki Kawai-Yamada,Lihua Jin,Aiko Hirata,Li-Hua Yu,Yoshiko Tone

doi:10.1074/jbc.m509632200

Abstract

Overexpression of the mammalian proapoptotic protein Bax induces cell death in plant and yeast cells. The Bax inihibitor-1 (BI-1) gene rescues yeast and plant from Bax-mediated lethality. Using the Arabidopsis BI-1 (AtBI-1) gene controlled by the GAL1 promoter as a cell death suppressor in yeast, Cdf1 (cell growth defect factor-1) was isolated from Arabidopsis cDNA library. Overexpression of Cdf1 caused cell death in yeast, whereas such an effect was suppressed by co-expression of AtBI-1. The Cdf1 protein fused with a green fluorescent protein was localized in the mitochondria and resulted in the loss of mitochondrial membrane potential in yeast. The Bax-resistant mutant BRM1 demonstrated tolerance against Cdf1-mediated lethality, whereas the Deltaatp4 strain was sensitive to Cdf1. Our results suggest that Cdf1 and Bax cause mitochondria-mediated yeast lethality through partially overlapped pathways.

Highlights

In yeast, cell death with apoptosis-like features has been reported after treatment with acetic acid, UV light irradiation, and H2O2
We reported previously that the expression of mammalian Bax in Arabidopsis plants results in apoptotic cell death, which could be suppressed by the coexpression of AtBI-1 [4]
The functions of Bax inhibitor-1 (BI-1) proteins are conserved across evolution and include cell death suppression activity for Bax-mediated lethality even in yeast and plant cells [4]

Summary

A Novel Arabidopsis Gene Causes Bax-like Lethality in Saccharomyces cerevisiae*

Overexpression of the mammalian proapoptotic protein Bax induces cell death in plant and yeast cells. The Pseudomonas AvrPtoB effecter protein, conserved among diverse genera of plant pathogens, acts to inhibit Bax-induced cell death [12]. We reported previously that the expression of mammalian Bax in Arabidopsis plants results in apoptotic cell death, which could be suppressed by the coexpression of AtBI-1 [4]. We devised a yeast genetic screening that allowed us to isolate plant genes responsible for cell death. For this purpose, we utilized the plant cell death suppressor AtBI-1 and found that overexpression of Cdf gene of Arabidopsis could induce apoptosis-like cell death in yeast. The effects of Cdf in yeast are partially similar to the mammalian Bax-induced lethality

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION