盐生盐杆菌DNA片段RM07的-35、-10区缺失分析

DELETION ANALYSIS OF DNA FRAGMENT RM07 FROM HALOBACTERIUM HALOBIUM

RM0 7DNA片段分离自嗜盐古菌———盐生盐杆菌R1 ,该片段不仅在嗜盐古菌内具有启动子功能 ,而且在大肠杆菌中也具有启动子活性。序列分析表明其上确实含有细菌启动子的 35、 1 0保守区。进一步通过缺失分析证实该片段就是在大肠杆菌中具启动功能的DNA片段 :仅含 1 0区而缺失 35区的RM0 7a片段基本上无启动活性 ;而含 35和 1 0区的0 1kb片段RM0 7b具有高于RM0 7的启动活性。研究结果还表明 ,RM0 7片段在大肠杆菌中的启动活性是受环境因素调节的 ,尤其是对氯化钠浓度的提高具有明显的相关性。因此RM0 7片段有可能成为构建双功能表达载体的新启动子资源 ,同时对进一步揭示古菌的融合特征及水平基因转移具有特殊意义。

The DNA fragment RM07 was isolated from halophilic archaea Halobacterium halobium, which can function as promoter not only in halophilic archaea, but also in Escherichia coli as eubacterial promoter. Sequencing analysis indicated that it possessed the typical consensus sequences (-35 and -10) of bacterial gene promoter, which was confirmed by further deletion analysis: With its -35 sequence deleted and -10 sequence left,DNA fragment RM07a nearly cannot initiate transcription;With its both -35 and -10 sequences,RM07b DNA fragment could be active as promoter at a level even higher than RM07. Our research also showed that the promoter function of RM07 fragment in Escherichia coli was under the control of environmental factors,especially its positive correlation with the increasing concentration of sodium chloride. Therefore, RM07 DNA fragment may be potential1 novel promoter source for constructing double-function vectors. It also has special significance in elucidating the issues of the fusing characteristics of archaea and lateral gene transfer between archaea and bacteria.