BIODEGRADATION OF MERCURIAL ANTISEPTICS AND PESTICIDES

有机汞抗性和生物降解基因（Omr） 包括防腐剂硫柳汞，消毒剂苯汞 醋酸盐和神经毒性杀真菌剂甲基汞，经常被发现在 细菌质粒沿着对无机化合物， 氯化汞 虽然无机汞电阻（Hgr）已被研究 广泛地说，人们对有机汞的耐受性知之甚少。 两年前，我们开始研究有机汞抗性， 接合IncM质粒，R83 lb. 虽然大小为90 kb，但R83 lb是 携带Omr基因座的最小天然质粒。 使用 转座子诱变和限制性内切酶分析，我们已经绘制了 R831 b仅携带Hgr和Omr两个选择标记。 我们发现 这些基因座相隔13.5kb，尽管事实上， 编码是协调调节的。 我们将Omr亚克隆到pBR 322中， 它与我们之前研究的Hgr mini-IncM复制子兼容， 克隆并已开始构建精细结构限制和缺失 两个基因座的图谱。 在本补助金的最后一年， 完成这些位点的限制性酶切图谱， 和galK融合体。 从长远来看，我们建议：（1）利用小细胞多肽分析， 表征R83 lb的Omr和Hgr基因座的基因产物;（2）以 使用插入和缺失检查Omr/Hgr表达的调节 突变体和lac和galK两者的同源系统的融合体（即， R83 lb基因座）以及异源系统（即包括R83 lb基因座和R83 lb基因座两者）的系统 和NR 1的mer操纵子的相关位点），并分离顺式- 和R83 lb中这些基因座的反式作用调控元件，并比较 （3）将Omr和Hgr DNA用作 探针，以探索这些位点的发生在我们的大量收集， 多重金属抗性细菌;和（4）对Omr和Hgr基因座进行测序 R83LB。 尚未对Omr基因座进行测序，尽管来自 质粒NR 1和相关的转座子Tn 501已经测序，我们的 多肽数据、DNA杂交数据和免疫扩散数据表明， R831 b的Hgr位点与NR 1/Tn 501的Hgr位点的亲缘关系不密切。

Genes of resistance to and biodegradation of organomercurials (Omr) including the antiseptic merthiolate, the disinfectant phenylmercuric acetate, and the neurotoxic fungicide methyl mercury, are often found on bacterial plasmids along with resistance to inorganic compounds such as HgCl2. Though inorganic mercury resistance (Hgr) has been studied extensively, much less is known about organomercury resistance. Two years ago we began to study the organomercury resistance determined by the conjugative IncM plasmid, R83lb. Though 90kb in size, R83lb is the smallest naturally occurring plasmid which carries the Omr locus. Using transposon mutagenesis and restriction enzyme analysis we have mapped the only two selectable markers carried by R83lb, Hgr and Omr. We found that these loci are separated by 13.5 kb despite the fact that the enzymes they encode are regulated co-ordinately. We have sub-cloned Omr into pBR322 which is compatible with the Hgr mini-IncM replicon we had previously cloned and have begun to construct fine structure restriction and deletion maps of both loci. During the last year of this present grant we will complete the restriction enzyme mapping of these loci and generate both lac and galK fusions in the parental plasmid and in sub-cloned derivatives. We propose for the long term: (1) to use minicell polypeptide analysis to characterize the gene products of the Omr and Hgr loci of R83lb; (2) to examine regulation of Omr/Hgr expression using insertion and deletion mutants and lac and galK fusions of both the homologous system (i.e. the R83lb loci) as well as of a heterologous system (i.e. including both R83lb and the correlate loci of the mer operon of NR1) and to isolate the cis- and trans-acting regulatory elements of these loci in R83lb and compare them with those of the NR1 mer operon; (3) to employ the Omr and Hgr DNA as probes to explore the occurrence of such loci in our large collection of multiple metal resistant bacteria; and (4) to sequence the Omr and Hgr loci of R83lb. No Omr locus has yet been sequenced and though Hgr loci from plasmid NR1 and the related transposon Tn501 have been sequenced, our polypeptide data, DNA hybridization data and immunodiffusion data indicate that the Hgr locus of R83lb is not closely related to that of NR1/Tn501.