Abstract
O. brevis is an orchis alga, and lives in the hydrosphere. It has high tolerance to various heavy metals (Ag, Cu, Zn and Cd). Our group has already clarified that its three genes, bmtA (metallothionein gene), bxa1 (heavy metal efflux pump gene) and bxmR (repressor gene), relate to resistant mechanisms to these heavy metals.
Precise DNA binding site of BxmR was analyzed by gel shift assay (EMSA) and DNA footprinting assay, and BxmR binds to an inverted repeat sequence, 12-2-12 domain, which exists in the upstream region of the bmtA and bxmR genes. Moreover, binding affinity of BxmR to the mutant DNA fragment including 12-2-12 domain was examined by EMSA.
Effect of Fe, Au, La and Cr on gene-expression of these three genes was also determined by EMSA. A remarkable effect of Au was observed in vitro and in vivo.
