A DISTANT 10-BP SEQUENCE SPECIFIES THE BOUNDARIES OF A PROGRAMMED DNA DELETION IN TETRAHYMENA
A DISTANT 10-BP SEQUENCE SPECIFIES THE BOUNDARIES OF A PROGRAMMED DNA DELETION IN TETRAHYMENA
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DOI：
10.1101/gad.7.12a.2357
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发表时间：
1993-12-01
影响因子：
10.5
通讯作者：
YAO, MC
中科院分区：
文献类型：
--
作者：
GODISKA, R;JAMES, C;YAO, MC
在研究的大多数纤毛虫中，程序性DNA缺失发生在数千个特定位点。为了了解这种突出的DNA重排过程的机制，我们通过对克隆DNA进行特异性突变并在体内测试其对重排的影响，分析了四膜虫中缺失的一个元件（m元件）。我们发现一个10 bp的多嘌呤序列（5'-AAAAAGGGGG）起着至关重要的作用。该序列位于元件两侧外侧较短的距离（约45bp）处。删除它将取消删除过程。将其移动一小段距离会导致删除边界随之移动。将该序列插入元素内的一个位点会在插入位点附近形成新的边界。序列分析表明，新边界均在距层序41 ~ 54 bp的范围内。因此，该序列对于确定DNA缺失的边界是必要和充分的，并且它从元件外的短距离处进行。这些结果为纤毛虫DNA缺失的控制提供了可能的解释，并表明一种新的位点特异性DNA重排机制参与其中。
Programmed DNA deletion occurs at thousands of specific sites in most ciliates studied. To understand the mechanism of this prominent DNA rearranging process, we analyzed one of the deletion elements (the M-element) in Tetrahymena by making specific mutations in cloned DNAs and testing their effects on rearrangement in vivo. We found that a 10-bp polypurine sequence (5'-AAAAAGGGGG) plays a crucial role. This sequence is located at a short distance (approximately 45 bp) outside of the element on either side. Removal of it abolishes the deletion process. Moving it short distances away causes the deletion boundary to move with it. Insertion of this sequence into a site within the element induces new boundaries to form near the insertion site. Sequence analysis reveals that all new boundaries created are 41-54 bp away from the sequence. Thus, this sequence is necessary and sufficient to determine the boundaries of DNA deletion, and it does so from a short distance outside of the element. These results offer a possible explanation for the control of DNA deletion in ciliates and suggest that a new type of mechanism for site-specific DNA rearrangements is involved.