HeT-A, a transposable element specifically involved in "healing" broken chromosome ends in Drosophila melanogaster.
HeT-A, a transposable element specifically involved in "healing" broken chromosome ends in Drosophila melanogaster.
复制标题
HeT-A，一种转座元件，专门参与“修复”黑腹果蝇断裂的染色体末端。
DOI：
10.1128/mcb.12.9.3910-3918.1992
复制
发表时间：
1992
影响因子：
5.3
通讯作者：
Pardue,ML
中科院分区：
文献类型：
--
作者：
Biessmann,H;Valgeirsdottir,K;Lofsky,A;Chin,C;Ginther,B;Levis,RW;Pardue,ML
8条最终缺失的果蝇黑胃染色体现已被发现“治愈”。在每种情况下，愈合的染色体末端都获得了来自HeT DNA家族的序列，这是一个复杂的重复序列家族，仅在端粒和中心外异染色质中发现。这些序列显然是由不涉及序列同源性的转置事件添加的。我们现在报道，在愈合这些染色体中的转座序列鉴定出一种新的转座元件，ht - a，它构成了HeT DNA家族的一个子集。在断裂的染色体末端添加HeT-A元素似乎是极性的。每个元件与断裂的染色体末端之间的近端连接是一个寡核苷酸(A)通道，从距离染色体末端5 ‘到3 ’的一条保守的AATAAA序列下游54个核苷酸开始。HeT-A元件的远端（端粒）端被截断；然而，我们还不能确定一个完整元件的极端远端序列。我们的分析涵盖了HeT-A元件的大约2600个核苷酸，从一端的寡核苷酸(A)区开始。序列同源性强（>75%）。序列可能对DNA结构而不是蛋白质编码保守；即使是最近转置的HeT-A元素在所研究的区域也缺乏重要的开放阅读框架。相反，这些元素表现出保守的短距离序列重复和碱基组成的周期性长期变化。这些保守的特征表明，HeT-A元件虽然是转座元件，但可能在端粒的组织或维持中具有结构作用。
Eight terminally deletedDrosophila melanogasterchromosomes have now been found to be “healed.” In each case, the healed chromosome end had acquired sequence from the HeT DNA family, a complex family of repeated sequences found only in telomeric and pericentric heterochromatin. The sequences were apparently added by transposition events involving no sequence homology. We now report that the sequences transposed in healing these chromosomes identify a novel transposable element, HeT-A, which makes up a subset of the HeT DNA family. Addition of HeT-A elements to broken chromosome ends appears to be polar. The proximal junction between each element and the broken chromosome end is an oligo(A) tract beginning 54 nucleotides downstream from a conserved AATAAA sequence on the strand running 5′ to 3′ from the chromosome end. The distal (telomeric) ends of HeT-A elements are variably truncated; however, we have not yet been able to determine the extreme distal sequence of a complete element. Our analysis covers approximately 2,600 nucleotides of the HeT-A element, beginning with the oligo(A) tract at one end. Sequence homology is strong (>75% between all elements studied). Sequence may be conserved for DNA structure rather than for protein coding; even the most recently transposed HeT-A elements lack significant open reading frames in the region studied. Instead, the elements exhibit conserved short-range sequence repeats and periodic long-range variation in base composition. These conserved features suggest that HeT-A elements, although transposable elements, may have a structural role in telomere organization or maintenance.