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Study of genome of pesticide-degrading bacteria as a representative of environmental bacterium

以环境细菌为代表的农药降解菌基因组研究

基本信息

批准号：
16580050
负责人：
NAGATA Yuji
金额：
$ 2.43万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

Mechanism for adaptation of environmental bacteria is of great interest. Sphingobium japonicum (formerly Sphingomonas paucimobilis) UT26 utilizes the important insecticide gamma-hexachlorocyclohexane (HCH) as a sole source of carbon and energy. In this study it was demonstrated that the UT26 genome consists three large circular replicons of 3.6 Mb, 670 kb, and 185 kb. The 3.6 Mb and the 670 kb replicons had one and two copies, respectively, of the 16S ribosomal RNA gene, and these replicons were designated as chromosomes (Chr) I and II, respectively. Chr I was indicated to be a main chromosome carrying the dnaA gene. The first three lin genes, linA to linC, for conversion of gamma-HCH to 2, 5-dichlorohydroquinone, were dispersed on Chr I. The 185 kb plasmid, pCHQ1, carried the linRED operon for the conversion of 2,5-dichlorohydroquinone to maleylacetate and was conjugatively transferred to another sphingomonad strain. The linF gene encoding maleylacetate reductase was located on Chr II. These results indicated that the genes for the complete gamma-HCH degradation are dispersed on the three large replicons of UT26. An endogenous insertion sequence of UT26, ISsp1, was identified, which may be involved in the rearrangement of the UT26 genome. Furthermore, it was revealed that metabolites of gamma-HCH had toxic effect on UT26, and a ABC-type transporter which was essential for the utilization of gamma-HCH in UT26 was identified. These results demonstrated the importance of factors except the catalyzing enzymes for the gamma-HCH assimilation in UT26.

环境细菌的适应机制引起了人们的极大兴趣。Sphingobium Japan onicum(前身为Sphingomonas paucimobilis)UT26利用重要的杀虫剂六氯环己烷(HCH)作为唯一的碳和能源来源。本研究证实了UT26基因组由3.6Mb、670kb和185kb三个大的环状复制子组成。3.6Mb和670kb的复制子分别含有1个和2个拷贝的16S核糖体RNA基因，分别命名为染色体(Chr)I和II。Chr I被认为是携带Dna A基因的主染色体。将三氯环己烷转化为2，5-二氯对苯二酚的前三个LIN基因LINA~LINC分散在Chr I上。185kb的pCHQ1携带2，5-二氯对苯二酚转化为顺丁烯二酸乙酯的linRED操纵子，并接合转移到另一神经鞘氨醇单胞菌中。编码马来酸乙酯还原酶的linF基因位于Chr II上。这些结果表明，伽马-六氯环己烷完全降解的基因分散在UT26的三个大复制子上。发现了UT26的内源插入序列ISsp1，它可能参与了UT26基因组的重排。此外，还发现γ-六氯环己烷的代谢产物对UT26有毒性作用，并鉴定出一种ABC型转运蛋白，它是UT26利用伽马-六氯环己烷所必需的。这些结果证明了除催化酶以外的其他因素对UT26中伽马-六氯环己烷同化的重要性。