STRUCTURE AND ORGANIZATION OF 2 DIVERGENT ALPHA-AMYLASE GENES FROM BARLEY
STRUCTURE AND ORGANIZATION OF 2 DIVERGENT ALPHA-AMYLASE GENES FROM BARLEY
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DOI：
10.1007/bf00017982
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发表时间：
1987-01-01
影响因子：
5.1
通讯作者：
MUTHUKRISHNAN, S
中科院分区：
文献类型：
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作者：
KNOX, CAP;SONTHAYANON, B;MUTHUKRISHNAN, S
我们已经从大麦DNA的Eco RI文库中分离到了几个α-淀粉酶基因组克隆。其中五个克隆显示了独特的限制图谱，并且它们与两个先前鉴定的α-淀粉酶cDNAs探针杂交的能力存在差异，这两个基因座分别代表α-AMY1(高PI)和α-AMY1。大麦6号和1号染色体上的AMY2(低等电点)。严格的杂交结果表明，五个基因组克隆中有四个含有α-AMY1序列，一个含有α-AMY2序列。从每个组的一个代表性基因组克隆中含有α-淀粉酶基因的区域已经被亚克隆、定位和测序。S1-核酸酶保护实验表明，这些克隆中包含的两个α-淀粉酶基因在糊粉组织中具有功能。这些基因的转录起始点是通过使用特定的合成寡核苷酸引物延伸来确定的。这两个α-淀粉酶基因包括启动子区域的DNA序列是不同的，预测的成熟蛋白和N-末端“先导”多肽的氨基酸序列也是不同的。α-AMY1基因有两个内含子，而α-AMY2基因有三个内含子。在编码区，每个基因与先前鉴定的相同基因类型的cDNA克隆相比，显示出7%-10%的序列差异。因此，核苷酸序列的差异可以解释α-淀粉酶亚家族之间以及同一亚家族成员之间的一些同工酶变异。虽然α-AMY1和α-AMY2基因启动子区域的核苷酸序列几乎没有同源性，但两者都含有一对可能构成调控位点的反向重复元件。
We have isolated several .alpha.-amylase genomic clones from an Eco RI library of barley DNA in .lambda.-Charon 32. Five of these clones exhibit unique restriction maps and differences in their abilities to hybridize with two previously characterized .alpha.-amylase cDNA probes representing two different loci, .alpha.-Amy 1 (high pI) and .alpha. Amy 2 (low pI) on barley chromosomes 6 and 1, respectively. Stringent hybridizations indicate that four of the five genomic clones contain .alpha.-Amy 1 sequences and one contains .alpha.-Amy 2 sequences. The regions containing .alpha.-amylase genes from one representative genomic clone of each group have been sub-cloned, mapped and sequenced. S1-nuclease protection experiments indicate that the two .alpha.-amylase genes contained in these clones are functional in aleurone tissue. Transcription start sites in these genes were determined by primer extension using specific synthetic oligonucleotide primers. The DNA sequences of the two .alpha.-amylase genes, including promoter regions, are divergent, as are the predicted amino acid sequences of the mature proteins and the N-terminal "leader" peptides. The .alpha.-Amy 1 gene contains two introns while the .alpha.-Amy 2 gene has three introns. In the coding region, each gene shows 7-10% sequence divergence with respect to the previously characterized cDNA clones of the same gene type. Therefore, differences in nucleotide sequences can account for some of the isozyme variations seen between the sub-families of .alpha.-amylases and among members of the same subfamily. Although the nucleotide sequences of the promoter regions of .alpha.-Amy 1 and .alpha.-Amy 2 genes show little homology, both contain pairs of inverted repeat elements which could constitute regulatory sites.