Schmidt-Bleek K, Heiser V, Thieck O, Brennicke A, Grohmann L
Institut für Genbiologische Forschung, Berlin, Germany.
Mol Gen Genet. 1997 Jan 27;253(4):448-54. doi: 10.1007/s004380050342.
The intrinsic 28.5-kDa iron-sulfur protein of complex I in the mitochondrial respiratory chain is encoded in the nucleus in animals and fungi, but specified by a mitochondrial gene in trypanosomes. In plants, the homologous protein is now found to be encoded by a single-copy nuclear gene in Arabidopsis thaliana and by two nuclear genes in potato. The cysteine motifs involved in binding two iron-sulfur clusters are conserved in the plant protein sequences. The locations of the seven introns, with sizes between 60 and 1700 nucleotides, are identical in the A. thaliana and the two potato genes, while their primary sequences diverge considerably. The A + T contents of the intron sequences range between 61% and 73%, as is characteristic for dicot plants, but are in some instances not higher than in the adjacent exons. Here, differences in T content may instead serve to discriminate exons and introns. In potato, both genes are expressed, with the highest levels found in flowers. Sequence similarities between the homologous nuclear and mitochondrial genes indicate that the nuclear forms in animals and plants originate from the endosymbiont genome.
线粒体呼吸链中复合物I的内在28.5 kDa铁硫蛋白在动物和真菌中由细胞核编码，但在锥虫中由线粒体基因指定。在植物中，现已发现同源蛋白在拟南芥中由单拷贝核基因编码，在马铃薯中由两个核基因编码。参与结合两个铁硫簇的半胱氨酸基序在植物蛋白序列中是保守的。七个内含子的位置，大小在60至1700个核苷酸之间，在拟南芥和两个马铃薯基因中是相同的，而它们的一级序列差异很大。内含子序列的A + T含量在61%至73%之间，这是双子叶植物的特征，但在某些情况下并不高于相邻外显子。在这里，T含量的差异反而可能用于区分外显子和内含子。在马铃薯中，两个基因都表达，在花中表达水平最高。同源核基因和线粒体基因之间的序列相似性表明，动物和植物中的核形式起源于内共生体基因组。
