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标题：Role of MerT and MerP from Pseudomonas K-62 Plasmid pMR26 in the Transport of Phenylmercury
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作者：Masako KIYONO ; Yoshio UNO ; Tomoko OMURA 等
期刊名称：Biological and Pharmaceutical Bulletin
印刷版ISSN：0918-6158
电子版ISSN：1347-5215
出版年度：2000
卷号：23
期号：3
页码：279-282
DOI：10.1248/bpb.23.279
出版社：The Pharmaceutical Society of Japan
摘要：To investigate the individual role of MerT and MerP encoded by Pseudomonas K-62 pMR26 in the transport of phenylmercury, a series of mutants with a specific point mutation in merT and/or genetic deletion in merP were constructed and transformed into Escherichia coil XL-1-Blue. Transport of phenylmercury across the cytoplasmic membrane of E. coli mediated by MerT and MerP was inhibited by NaCN and by cold temperatures. Deletion of merP reduced, but did not completely abolish the C₆H₅Hg⁺-hyperuptake and -hypersensitive phenotypes suggesting that transport of phenylmercury into the cytoplasm of E. coli is still occurring. Mutations of the vicinal cysteine residues (Cys24 and Cys25) in the first transmembrane region of MerT to serine caused complete loss of Hg²⁺-hyperuptake and -hypersensitivity, whereas the mutations did not affect the C₆H₅Hg⁺-hyperuptake and -hypersensitive phenotypes. In addition, no additive effect on the C₆H₅Hg⁺-hyperuptake and -hypersensitive phenotypes was found, when mutations of the two cysteines in MerT to serine were further introduced in the merP-deleted mutants. These results clearly demonstrated that the vicinal cysteine residues of MerT are not involved in the transport of C₆H₅Hg⁺, but indeed are involved in the transport of Hg²⁺ as previously reported.
关键词：MerT;MerP;phenylmercury transport;hypersensitivity;hyperuptake;vicinal cysteine pair