Qin M M, Robertson D S, Ellingboe A H
Department of Genetics, University of Wisconsin, Madison 53706.
Genetics. 1991 Nov;129(3):845-54. doi: 10.1093/genetics/129.3.845.
The identification of the autonomous or transposase-encoding element of the Mutator (Mu) transposable element system of maize is necessary to the characterization of the system. We reported previously that a transcript homologous to the internal region of the MuA element is associated with activity of the Mutator system. We describe here the cloning of another Mu element, designated MuA2, that cosegregates with Mutator activity as assayed by somatic instability of the a1-Mum2 allele. The MuA2 element has features typical of the transposable elements of the Mutator family, including the 210-bp terminal inverted repeats. Several lines of evidence suggest that MuA2 is an autonomous or transposase-encoding element of the Mu family: (1) MuA2 cosegregates with a genetically defined element that regulates somatic mutability of the a1-Mum2 allele; (2) MuA2 is hypomethylated while most other MuA2-hybridizing sequences in the genome are extensively methylated; (3) the increase of the copy number of MuA2 is concomitant with the increase of regulator elements; (4) MuA2-like elements are found in Mutator lines but not in non-Mutator inbreds. We propose that autonomous or transposase-encoding elements of the Mu family may be structurally conserved and MuA2-like.
鉴定玉米Mutator（Mu）转座子系统的自主元件或转座酶编码元件对于该系统的特性描述至关重要。我们之前报道过，一种与MuA元件内部区域同源的转录本与Mutator系统的活性相关。我们在此描述另一种Mu元件MuA2的克隆，该元件与通过a1 - Mum2等位基因的体细胞不稳定性检测的Mutator活性共分离。MuA2元件具有Mutator家族转座子的典型特征，包括210bp的末端反向重复序列。几条证据表明MuA2是Mu家族的自主元件或转座酶编码元件：（1）MuA2与一个遗传定义的调节a1 - Mum2等位基因体细胞突变性的元件共分离；（2）MuA2发生低甲基化，而基因组中大多数其他与MuA2杂交的序列则被广泛甲基化；（3）MuA2拷贝数的增加与调节元件的增加同时发生；（4）在Mutator系中发现了MuA2样元件，但在非Mutator自交系中未发现。我们提出，Mu家族的自主元件或转座酶编码元件在结构上可能是保守的且类似MuA2。
