Bae W, Mehra R K, Mulchandani A, Chen W
Department of Chemical and Environmental Engineering, University of California, Riverside, California 92521, USA.
Appl Environ Microbiol. 2001 Nov;67(11):5335-8. doi: 10.1128/AEM.67.11.5335-5338.2001.
Synthetic phytochelatins (ECs) are a new class of metal-binding peptides with a repetitive metal-binding motif, (Glu-Cys)(n)Gly, which were shown to bind heavy metals more effectively than metallothioneins. However, the limited uptake across the cell membrane is often the rate-limiting factor for the intracellular bioaccumulation of heavy metals by genetically engineered organisms expressing these metal-binding peptides. In this paper, two potential solutions were investigated to overcome this uptake limitation either by coexpressing an Hg(2+) transport system with (Glu-Cys)(20)Gly (EC20) or by directly expressing EC20 on the cell surface. Both approaches were equally effective in increasing the bioaccumulation of Hg(2+). Since the available transport systems are presently limited to only a few heavy metals, our results suggest that bioaccumulation by bacterial sorbents with surface-expressed metal-binding peptides may be useful as a universal strategy for the cleanup of heavy metal contamination.
合成植物螯合肽（ECs）是一类新型的金属结合肽，具有重复的金属结合基序（Glu-Cys）(n)Gly，已证明其结合重金属的能力比金属硫蛋白更强。然而，跨细胞膜的摄取有限往往是表达这些金属结合肽的基因工程生物体对重金属进行细胞内生物累积的限速因素。在本文中，研究了两种潜在的解决方案来克服这种摄取限制，即与（Glu-Cys）20Gly（EC20）共表达汞离子（Hg2+）转运系统，或直接在细胞表面表达EC20。两种方法在增加Hg2+的生物累积方面同样有效。由于目前可用的转运系统仅限于少数几种重金属，我们的结果表明，具有表面表达金属结合肽的细菌吸附剂进行生物累积可能是一种用于清除重金属污染的通用策略。
