Shao Z Q, Behki R
Centre for Land and Biological Resources Research, Agriculture and Agri-Food Canada, Ottawa, Ontario.
Appl Environ Microbiol. 1995 May;61(5):2061-5. doi: 10.1128/aem.61.5.2061-2065.1995.
The degradation of the herbicides EPTC (S-ethyl dipropylthiocarbamate) and atrazine (2-chloro-4-ethyl-amino-6-isopropylamino-1,3,5-triazine) is associated with an indigenous plasmid in Rhodococcus sp. strain TE1. Plasmid DNA libraries of Rhodococcus sp. strain TE1 were constructed in a Rhodococcus-Escherichia coli shuttle vector, pBS305, and transferred into Rhodococcus sp. strain TE3, a derivative of Rhodococcus sp. strain TE1 lacking herbicide degradation activity, to select transformants capable of growing on EPTC as the sole source of carbon (EPTC+). Analysis of plasmids from the EPTC+ transformants indicated that the eptA gene, which codes for the enzyme required for EPTC degradation, residues on a 6.2-kb KpnI fragment. The cloned fragment also harbored the gene required for atrazine N dealkylation (atrA). The plasmid carrying the cloned fragment could be electroporated into a number of other Rhodococcus strains in which both eptA and atrA were fully expressed. No expression of the cloned genes was evident in E. coli strains. Subcloning of the 6.2-kb fragment to distinguish between EPTC- and atrazine-degrading genes was not successful.
除草剂EPTC（S-乙基二丙基硫代氨基甲酸盐）和阿特拉津（2-氯-4-乙氨基-6-异丙氨基-1,3,5-三嗪）的降解与红球菌属TE1菌株中的一种内源质粒有关。利用红球菌-大肠杆菌穿梭载体pBS305构建了红球菌属TE1菌株的质粒DNA文库，并将其转入红球菌属TE3菌株（红球菌属TE1菌株的一个衍生物，缺乏除草剂降解活性），以筛选能够以EPTC作为唯一碳源生长的转化体（EPTC+）。对来自EPTC+转化体的质粒分析表明，编码EPTC降解所需酶的eptA基因位于一个6.2 kb的KpnI片段上。克隆片段还含有阿特拉津N-脱烷基化所需的基因（atrA）。携带克隆片段的质粒可以通过电穿孔导入许多其他红球菌菌株，eptA和atrA在这些菌株中均能充分表达。在大肠杆菌菌株中未观察到克隆基因的表达。对6.2 kb片段进行亚克隆以区分EPTC降解基因和阿特拉津降解基因未获成功。
