A COXIELLA-BURNETII REPEATED DNA ELEMENT RESEMBLING A BACTERIAL INSERTION-SEQUENCE
A COXIELLA-BURNETII REPEATED DNA ELEMENT RESEMBLING A BACTERIAL INSERTION-SEQUENCE
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DOI：
10.1128/jb.174.17.5540-5548.1992
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发表时间：
1992-09-01
影响因子：
3.2
通讯作者：
WILLIAMS, JC
中科院分区：
文献类型：
--
作者：
HOOVER, TA;VODKIN, MH;WILLIAMS, JC
经Southern blotting鉴定，位于伯氏柯克斯体htpAB操纵子3‘端的DNA片段存在于九里氏基因组中，约有19个拷贝。分析了这个与htpAB相关的重复元件和另外两个独立拷贝的DNA序列，以确定该元件的大小和性质。该元件的三个拷贝的长度分别为1,450、1,452和1,458bp，三个序列之间的差异小于2%。发现了细菌插入序列的几个特征。其中包括一个重要的开放阅读框，它将编码一个预测为高度碱性的367个氨基酸的多肽，具有与DNA结合的螺旋-转弯-螺旋基序，具有亮氨酸拉链基序，并与其他几个细菌插入序列中的多肽具有同源性。在该元件的所有三个拷贝的末端都发现了相同的7-bp反向重复序列。然而，在插入事件期间，受体DNA中的许多细菌移动元件产生的复制并不在所研究的三个伯氏梭菌元件中的任何一个的反向重复序列的两侧。在该元件的所有三个拷贝中也发现了位于开放阅读框架两侧的第二对反向重复序列。该元件的三个拷贝之间的大部分分歧发生在该元件3‘端的两个反向重复序列之间的区域。尽管序列发生了变化，但该元件的所有三个副本在该区域都保持了显著的二联体对称性。
A DNA fragment located on the 3' side of the Coxiella burnetii htpAB operon was determined by Southern blotting to exist in approximately 19 copies in the Nine Mile I genome. The DNA sequences of this htpAB-associated repetitive element and two other independent copies were analyzed to determine the size and nature of the element. The three copies of the element were 1,450, 1,452, and 1,458 bp long, with less than 2% divergence among the three sequences. Several features characteristic of bacterial insertion sequences were discovered. These included a single significant open reading frame that would encode a 367-amino-acid polypeptide which was predicted to be highly basic, to have a DNA-binding helix-turn-helix motif, to have a leucine zipper motif, and to have homology to polypeptides found in several other bacterial insertion sequences. Identical 7-bp inverted repeats were found at the ends of all three copies of the element. However, duplications generated by many bacterial mobile elements in the recipient DNA during insertion events did not flank the inverted repeats of any of the three C. burnetii elements examined. A second pair of inverted repeats that flanked the open reading frame was also found in all three copies of the element. Most of the divergence among the three copies of the element occurred in the region between the two inverted repeat sequences in the 3' end of the element. Despite the sequence changes, all three copies of the element have retained significant dyad symmetry in this region.