Chen C H, Oishi K K, Kloeckener-Gruissem B, Freeling M
Genetics. 1987 Jul;116(3):469-77. doi: 10.1093/genetics/116.3.469.
A new, unstable, organ-specific Adh1 mutant was isolated from a Robertson's mutator line by germinating kernels under partial anaerobic conditions. Families of kernels which showed segregation of a conditional anaerobic lethal phenotype were identified. One mutant, Adh1-3F1124, was shown to express approximately 6% normal levels of ADH1 in seed and anaerobically treated seedlings but expresses normal levels of ADH1 in pollen, the male gametophyte. The ADH1 polypeptide encoded by the mutant allele was found to be indistinguishable from that encoded by the Adh1-3F progenitor but its message levels were lower in seed and seedlings. Robertson's mutator lines are known to carry Mu transposons that cause increased mutation rates. Genomic Southern analysis of Adh1-3F1124 and Adh1-3F showed the presence of a 1.85 kbp insertion at the 5' region of Adh1. Comparison of the DNA sequences revealed that a Mu 1-like element was inserted 31 bp 5' from the transcriptional start site of Adh1-3F1124 gene. The insertion of the Mu element creates an additional TATA box by duplicating the 9 bp genomic sequence--ATATAAATC--at the site of insertion. Consequently, there are two potentially functional TATA sequences, separated by the 1.85 kbp Mu element, 5' to the transcriptional start site. It is not yet understood how such an arrangement alters the organ-specific expression of Adh1.
通过在部分厌氧条件下发芽谷粒，从罗伯逊突变体系中分离出一种新的、不稳定的、器官特异性的Adh1突变体。鉴定出表现出条件性厌氧致死表型分离的谷粒家族。其中一个突变体Adh1-3F1124在种子和经厌氧处理的幼苗中表达的ADH1水平约为正常水平的6%，但在雄配子体花粉中表达正常水平的ADH1。发现突变等位基因编码的ADH1多肽与Adh1-3F祖细胞编码的多肽无法区分，但其在种子和幼苗中的信使水平较低。已知罗伯逊突变体系携带导致突变率增加的Mu转座子。对Adh1-3F1124和Adh1-3F进行基因组Southern分析，结果显示在Adh1的5'区域存在一个1.85 kbp的插入片段。DNA序列比较表明，一个类Mu 1元件插入到Adh1-3F1124基因转录起始位点5'端31 bp处。Mu元件的插入通过在插入位点重复9 bp的基因组序列——ATATAAATC——产生了一个额外的TATA框。因此，在转录起始位点5'端有两个潜在的功能性TATA序列，被1.85 kbp的Mu元件隔开。目前尚不清楚这种排列如何改变Adh1的器官特异性表达。
