Degenerate MAGGY elements in a subgroup of Pyricularia grisea:: a possible example of successful capture of a genetic invader by a fungal genome
Degenerate MAGGY elements in a subgroup of Pyricularia grisea:: a possible example of successful capture of a genetic invader by a fungal genome
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DOI：
10.1007/s004380051044
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发表时间：
1999-07-01
期刊：
影响因子：
--
通讯作者：
Mayama, S
中科院分区：
文献类型：
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作者：
Nakayashiki, H;Nishimoto, N;Mayama, S
LTR-反转录转座子MAGGY在稻瘟病菌（Magnaporthe grisea）的分离株中零星存在。基于通过rDNA的RFLP分析构建的系统树，携带MAGGY元件的分离物被归类为一个由四种rDNA类型组成的簇。然而，在这个集群的一些成员中，以来自普通小米（Panicum miliaceum）的分离物为例，MAGGY元件具有独特的特征。Southern分析表明，这些菌株拥有一个单一的拷贝的MAGGY相关序列的限制性内切酶图谱不同于MAGGY本身。序列分析表明，MAGGY相关序列是MAGGY的简并形式，其特征在于许多C：G到T：A的转换，这通常是由RIP（重复诱导的点突变）或RIP样过程引起的。然而，通过检查总共501个位点，确定了该真菌中C：G到T：A转变的有利靶位点是（A/T）pCp（A/T），这不同于最初在脉孢菌中报道的RIP过程（CpA），也不同于曲霉菌中报道的RIP过程（CpC）。MAGGY携带者集群的某些成员保留了退化MAGGY元件的单个拷贝，这一事实意味着这些分离物的祖先成功地“捕获”了入侵的MAGGY元件。
The LTR-retrotransposon MAGGY is found sporadically in isolates of Pyricularia grisea (Magnaporthe grisea). Based on a dendrogram constructed by RFLP analysis of rDNA, isolates that carry MAGGY elements were classified into a single cluster that comprised four rDNA types. However, in a few members of this cluster, exemplified by isolates from common millet (Panicum miliaceum), the MAGGY element has distinct features. Southern analysis suggested that these isolates possessed a single copy of a MAGGY-related sequence whose restriction map differed from that of MAGGY itself. Sequence analysis revealed that the MAGGY-related sequence was a degenerate form of MAGGY, characterized by numerous C:G to T:A transitions, which have often been reported to result from RIP (Repeat-induced point mutation) or RIP-like processes. However, the favored target site for C:G to T:A transitions in this fungus, determined by examining a total of 501 sites, was (A/T)pCp(A/T), which differs from that for the RIP process originally reported in Neurospora (CpA), and from that reported in Aspergillus (CpC). The fact that certain members of the cluster of MAGGY carriers retain a single copy of a degenerate MAGGY element implies that the ancestor of these isolates successfully "captured" the invading MAGGY element.