A glutathione S-transferase from Proteus mirabilis involved in heavy metal resistance and its potential application in removal of Hg²⁺

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• 作者：Weiwei Zhang ; Kun Yin ; Bowei Li ; Lingxin Chen
• 关键词：Glutathione S-transferase ; Proteus mirabilis ; Heavy metal ; Surface display ; Adsorption
• 刊名：Journal of Hazardous Materials
• 出版年：15 October, 2013
• 年：2013
• 卷：261
• 期：Complete
• 页码：646-652
• 全文大小：1357 K

文摘

Glutathione S-transferases (GSTs) are a family of multifunctional proteins playing important roles in detoxification of harmful physiological and xenobiotic compounds in organisms. In our study, a gene encoding a GST from Proteus mirabilis strain V7, gst_Pm-4, was cloned and conditionally expressed in Escherichia coli strain BL21(DE3). The purified Gst_Pm-4 protein, with an estimated molecular mass of approximately 23 kDa, was able to conjugate 1-chloro-2,4-dinitrobenzene and bind to the GSH-affinity matrix. Real-time reverse transcriptase PCR suggested that mRNA level of gst_Pm-4 was increased in the presence of CdCl₂, CuCl₂, HgCl₂ and PbCl₂, respectively. Correspondingly, overexpression of gst_Pm-4 in the genetically engineered bacterium Top10/pLacpGst exhibited higher heavy metal resistance compared to the control Top10/pLacP3. Another genetically engineered bacterium Top10/pBATGst, in which the DNA encoding Gst_Pm-4 protein was fused with the DNA encoding Pfa1-based auto surface display system, was built. Top10/pBATGst could constitutively express the chimeric Gst_Pm-4 and anchor it onto the cell surface subsequently. Almost 100% of the Hg²⁺ within the range of 0.1-100 nM was adsorbed by Top10/pBATGst, and 80% of the bounded Hg²⁺ could be desorbed from bacterial cells when pH was adjusted to 6.0. Thus, Top10/pBATGst can be potentially used for efficient treatment of Hg²⁺-contaminated aquatic environment.