Nakahara H, Silver S, Miki T, Rownd R H
J Bacteriol. 1979 Oct;140(1):161-6. doi: 10.1128/jb.140.1.161-166.1979.
The region of plasmid NR1 concerned with resistance to Hg2+ and organomercurials consists of sequences found on restriction endonuclease fragments EcoRI-H and EcoRI-I. When both fragments were cloned together into a derivative of plasmid ColE1, the hybrid plasmid conferred properties indistinguishable from those of the parental plasmid, NR1: resistance to Hg2+ and to the organomercurials merbromin and fluoresceinmercuric acetate and the inducible synthesis of the enzyme mercuric reductase. When fragment EcoRI-I was cloned into plasmid ColE1, cells containing the plasmid was as sensitive to Hg2+ and organomercurials as plasmidless strains. When fragment EcoRI-H was cloned into ColE1, cells with the hybrid plasmid were hypersensitive to Hg2+ and organomercurials. This hypersensitivity was inducible by prior exposure to low, subtoxic Hg2+ or merbromin levels. It was associated with an inducible hyperbinding activity attributed to a gene governing Hg2+ uptake and found on fragment EcoRI-H (which contains the proximal portion of a mercuric resistance [mer] operon).
质粒NR1中与对Hg2+和有机汞化合物抗性相关的区域，由存在于限制性内切酶片段EcoRI - H和EcoRI - I上的序列组成。当这两个片段一起克隆到质粒ColE1的一个衍生物中时，该杂种质粒赋予的特性与亲本质粒NR1的特性无法区分：对Hg2+、有机汞化合物红汞和荧光素汞醋酸盐具有抗性，以及可诱导合成汞还原酶。当片段EcoRI - I克隆到质粒ColE1中时，含有该质粒的细胞对Hg2+和有机汞化合物的敏感性与无质粒菌株相同。当片段EcoRI - H克隆到ColE1中时，含有杂种质粒的细胞对Hg2+和有机汞化合物高度敏感。这种超敏性可通过预先暴露于低水平、亚毒性的Hg2+或红汞水平来诱导。它与一种可诱导的超结合活性有关，该活性归因于一个控制Hg2+摄取的基因，且存在于片段EcoRI - H上（其包含汞抗性[mer]操纵子的近端部分）。
