The structure of a chromosomal leghaemoglobin gene from soybean
The structure of a chromosomal leghaemoglobin gene from soybean
复制标题
大豆染色体豆血红蛋白基因的结构
作者：
E. O. Jensen;Kirsten Paludan;Jens Jørgen Hyldig;Peter L. Jørgensen;Kjeld A. Marcker
豆血红蛋白（Lb）仅在与根瘤菌共生的豆科植物的固氮根瘤中发现。大豆根瘤含有三种主要形式的Lb，分别称为a，c1和c2。最近已经确定了三个Lb的氨基酸序列1。Lb a与两个c品种在六个氨基酸上不同，而Lb c1和c2仅在一个氨基酸上不同。我们最近报道了一个含有大豆Lb cDNA序列的杂交质粒的分离2。以一个这样的克隆为探针，从以λgt Wes·λB为载体构建的大豆DNA文库中分离出5个含有染色体L B基因的不同片段。对其中一个分离的染色体Lb基因的详细分析显示存在三个间插序列。通过所有已知的珠蛋白氨基酸序列的同源性比对显示，Lb编码序列中的第一和第三间插序列的剪接点位于与在所有其它已知的珠蛋白编码序列中发现的两个中断相同的位置。
Leghaemoglobin (Lb) has only been found in the nitrogen-fixing root nodules of legumes symbiotically associated with Rhizobia. Soybean nodules contain three major forms of Lb called a, c1 and c2, respectively. The amino acid sequences of the three Lbs have been determined recently1. Lb a differs from the two c varieties in six amino acids, while Lb c1 and c2 differ in only one amino acid. We have recently reported the isolation of a hybrid plasmid containing soybean Lb cDNA sequences2. Using one such clone as a probe, we have isolated five different soybean DNA fragments containing chromosomal Lb genes from a soybean DNA library which was constructed using lambda λgt Wes·λB as vector. The detailed analysis of one of the isolated chromosomal Lb genes revealed the presence of three intervening sequences. Alignment by homology of all known globin amino sequences shows that the splicing points of the first and the third intervening sequences in the Lb-coding sequence are located in the same positions as the two interruptions found in all other known globin-coding sequences.