Poster: Heavy metals & phytoremediation

Abs # 52: Heterologous expression of a mammalian ABC protein in plant and its transport activity

Presenter:	Nakanishi, Tsugumi , tsugumi@spring8.or.jp
Authors	Nakanishi, Tsugumi  (A)   Satoshi, Konagai  (B)   Nao, Yamanaka  (B)   Kazumitsu, Ueda  (C)   Shuji, Kaneko  (A)   Fumihiko, Sato  (B)   Kazufumi, Yazaki  (D)
Affiliations:	(A): Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University (B): Graduate School of Biostudies, Kyoto University (C): Laboratory of Cellular Biochemistry, Graduate School of Agriculture, Kyoto University (D): Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University

ABC proteins involved in multidrug resistance of cancer cells show ability to efflux cytotoxic compounds of wide variety in their chemical structures and biological activities, which confers the cells multiple tolerance against these compounds. By the "transport engineering" using such an ABC protein gene, multidrug resistance-associated protein-1 (MRP-1) as a molecular tool, we established transgenic tobacco plants, which showed resistance to daunorubicin and cadmium that were substrates of MRP-1. While ABC proteins of MRP subfamily are localized at the plasma membrane in mammalian cells, human MRP-1 was localized at the vacuolar membrane when expressed in tobacco cells. MRP-1 protein expressed in tobacco leaves appears at 180 kDa in SDS-PAGE, which is ca. 10 kDa smaller than that of the native one, suggesting the difference in N-glycoxylation pattern because of the heterologous host. The MRP-1-expressing tobacco cells also exhibited the activity to absorb daunorubicin and cadmium from the medium and sequestrate them in the vacuolar matrix. These results offer a new aspect in phytoremediation that a single transformation with a heterologous ABC protein recognizing multiple substrates will be utilized as a molecular pump to extract environmental pollutants and to accumulate them in the plant body, which is applicable to complex pollution by organic and inorganic compounds in the soil.