Mercurial-resistance determinants in Pseudomonas strain K-62 plasmid pMR68

我们报道了从假单胞菌K-62菌株中分离的质粒pMR 68的完整核苷酸序列，这两个质粒有助于广谱汞抗性，其中一个质粒（pMR 26）的mer操纵子先前已被表征。质粒（pMR 68）的长度为71，020 bp。鉴定了三个mer基因簇。第一个包含merR-orf 4-orf 5-merT 1-merP 1-merF-merA-merB 1，其赋予细菌对汞离子和有机汞的抗性。第二和第三簇分别包含编码汞转运系统的merT 2-merP 2和编码有机汞裂解酶的merB 2。携带pMKY 12（含有从pMR 68克隆的merR-orf 4-orf 5-merT 1-merP 1-merF-merA-merB 1）的大肠杆菌细胞比对照细胞对汞离子和苯基汞的抗性更强，挥发更多的汞。在pMR 68中鉴定的新mer基因可能有助于我们设计针对汞污染物生物修复的新策略。

We report the complete nucleotide sequence of plasmid pMR68, isolated from Pseudomonas strain K-62, two plasmids contribute to broad-spectrum mercury resistance and that the mer operon from one of them (pMR26) has been previously characterized. The plasmid (pMR68) was 71,020 bp in length. Three mer gene clusters were identified. The first comprised merR-orf4-orf5-merT1-merP1-merF-merA-merB1, which confers bacterial resistance to mercuric ions and organomercury. The second and third clusters comprised merT2-merP2, which encodes a mercury transport system, and merB2, which encodes an organomercurial lyase, respectively. Escherichia coli cells carrying pMKY12 (containing merR-orf4-orf5-merT1-merP1-merF-merA-merB1 cloned from pMR68) were more resistant to, and volatilized more, mercury from mercuric ions and phenylmercury than the control cells. The novel mer gene identified in pMR68 may help us to design new strategies aimed at the bioremediation of mercurials.