Pfeifer F, Blaseio U
Max-Planck-Institut für Biochemie, Martinsried, FRG.
Nucleic Acids Res. 1990 Dec 11;18(23):6921-5. doi: 10.1093/nar/18.23.6921.
Investigation of the plasmid pHH4 in single colonies of Halobacterium halobium PHH4 indicated transposition of insertion elements in 20% of the colonies. Seven ISH27 insertions were observed as well as one ISH23 insertion. The various copies of ISH27 were compared to the two ISH27 elements already present in pHH4, and to the ISH27 element that was identified in the bacteriopsin (bop) gene of a Bop mutant. These ten copies of ISH27 constitute three types on the basis of DNA sequence identity: ISH27-1 (1398 bp), ISH27-2, and ISH27-3 (1389 bp each). The DNA sequence comparison between the three types indicates a region of 1200 bp where the identity between ISH27-1 and ISH27-2 or ISH27-3 is 82-83%. ISH27-2 and ISH27-3 are 95% identical in this region. The remaining region exhibits a lower DNA similarity (64-74% identity) between the different copies. An open reading frame of 1167 nucleotides spans the more conserved region, and a corresponding transcript could be detected in H. halobium PHH4, but not in H. halobium wild-type. ISH27-1 is 91% identical to members of the insertion sequence-like elements ISH51 of Haloferax volcanii, whereas the other two ISH27 element types are 82-83% identical to ISH51. The transposition 'burst' of ISH27 was only seen after storage of the cells for more than two years at 4 degrees C. Upon continuous cultivation at 37 degrees C no transposition event could be observed, suggesting that stress factor(s) might have caused the high transposition rate.
对嗜盐嗜盐菌PHH4单菌落中的质粒pHH4进行的研究表明，20%的菌落中存在插入元件的转座现象。观察到7个ISH27插入以及1个ISH23插入。将ISH27的各种拷贝与pHH4中已有的两个ISH27元件以及在Bop突变体的视紫红质（bop）基因中鉴定出的ISH27元件进行了比较。这10个ISH27拷贝根据DNA序列同一性构成三种类型：ISH27-1（1398 bp）、ISH27-2和ISH27-3（各1389 bp）。三种类型之间的DNA序列比较表明，ISH27-1与ISH27-2或ISH27-3之间在1200 bp区域的同一性为82-83%。ISH27-2和ISH27-3在该区域的同一性为95%。其余区域在不同拷贝之间表现出较低的DNA相似性（同一性为64-74%）。一个1167个核苷酸的开放阅读框跨越了更保守的区域，并且在嗜盐嗜盐菌PHH4中可以检测到相应的转录本，但在嗜盐嗜盐菌野生型中未检测到。ISH27-1与火山盐红菌的插入序列样元件ISH51的成员有91%的同一性，而其他两种ISH27元件类型与ISH51有82-83%的同一性。ISH27的转座“爆发”仅在细胞于4℃储存两年以上后才出现。在37℃连续培养时未观察到转座事件，这表明应激因素可能导致了高转座率。
