Kuroda Kouichi, Ueda Mitsuyoshi
Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Japan.
Appl Microbiol Biotechnol. 2006 Apr;70(4):458-63. doi: 10.1007/s00253-005-0093-8. Epub 2005 Aug 10.
To increase the level of adsorption of heavy metal ions in surface-engineered yeasts, a yeast metallothionein (YMT) was tandemly fused and displayed by means of an alpha-agglutinin-based display system. The display of the YMT and its tandem repeats was examined by immunofluorescent labeling. The adsorption and recovery of Cd(2+) on the cell surface was increasingly enhanced with increasing number of tandem repeats. All Cd(2+)-binding sites in the YMT tandem repeats were suggested to be completely occupied. To investigate the relationship between cell-surface adsorption and protection against heavy metal ion toxicity, the tolerance of these surface-engineered yeasts to Cd(2+) was examined by growing in Cd(2+)-containing liquid medium. The rate of growth was found to be dependent on the number of displayed tandem repeats of YMT. These results suggest that the characteristics of surface-engineered yeasts as a bioadsorbent were dependent on the ability of the displayed proteins to bind metal ions, and the adsorption of heavy metal ions on the cell surface plays a major role in the ability of the cells to resist the toxic effects of metal ions.
为提高表面工程酵母中重金属离子的吸附水平，通过基于α-凝集素的展示系统串联融合并展示酵母金属硫蛋白（YMT）。通过免疫荧光标记检测YMT及其串联重复序列的展示情况。随着串联重复序列数量的增加，细胞表面对Cd(2+)的吸附和回收能力逐渐增强。推测YMT串联重复序列中所有的Cd(2+)结合位点均被完全占据。为研究细胞表面吸附与抵御重金属离子毒性之间的关系，通过在含Cd(2+)的液体培养基中培养来检测这些表面工程酵母对Cd(2+)的耐受性。发现生长速率取决于展示的YMT串联重复序列的数量。这些结果表明，表面工程酵母作为生物吸附剂的特性取决于展示蛋白结合金属离子的能力，并且重金属离子在细胞表面的吸附在细胞抵抗金属离子毒性的能力中起主要作用。
