Poster: Late and Moved Abstracts

Abs # 1003: Ubiquitin-dependent protein degradation may play an important role in enhancing metal tolerance in plants

Presenter:	Hwang, Seongbin , sbhwang@sejong.ac.kr
Authors	Hwang, Seongbin  (A)   Lee, ChangEun  (A)
Affiliations:	(A): Sejong University, Dept. of Molecular Biology

Ubiquitination genes AtAsT1, NtCdT24 and NtAsT8 were cloned by complementing arsenite-sensitive mutant AsS5 and AsS78 and cadmium-sensitive mutant CdS4 of S. cerevisiae with the yeast expression library of Arabidopsis thaliana and Nicotiana tabacum. AtAsT1(457aa), NtCdT24(156aa) and NtAsT8(152aa) had high homology to poly-ubiquitin, ubiquitin-extension protein and ubiquitin-conjugating enzyme, respectively. To confirm roles of three genes, they were over-expressed in AsS5, CdS4, AsS78 and WT (Y800), respectively. Expression of each gene increased a tolerance to metal, but decreased metal accumulation both in WT and metal-sensitive mutants. In addition, over-expression of AtAsT1 elevated As tolerance in the transgenic rice. Taken together, it is concluded that three novel genes of Arabidopsis and N. tabacum which are involved in ubiquitin-dependent protein degradation play roles in increasing metal tolerance in S. cerevisiae and O. sativa. These data support a hypothesis that ubiquitin-mediated protein degradation system increases a metal tolerance via removing metal-induced denatured proteins. These genes also can be applied to producing low-metal accumulating crops and metal phytoremediators using an anti-sense technique.