CLONING, NUCLEOTIDE-SEQUENCES AND DIFFERENTIAL EXPRESSION OF THE NIFH AND NIFH-LIKE (FRXC) GENES FROM THE FILAMENTOUS NITROGEN-FIXING CYANOBACTERIUM PLECTONEMA-BORYANUM
CLONING, NUCLEOTIDE-SEQUENCES AND DIFFERENTIAL EXPRESSION OF THE NIFH AND NIFH-LIKE (FRXC) GENES FROM THE FILAMENTOUS NITROGEN-FIXING CYANOBACTERIUM PLECTONEMA-BORYANUM
复制标题
DOI：
10.1093/oxfordjournals.pcp.a078173
复制
发表时间：
1991-10-01
影响因子：
4.9
通讯作者：
MATSUBARA, H
中科院分区：
文献类型：
--
作者：
FUJITA, Y;TAKAHASHI, Y;MATSUBARA, H
frxC 基因存在于苔类叶绿体 DNA 中，编码一种功能未知的蛋白质。推导的该蛋白的氨基酸序列与nifH基因编码的固氮酶Fe蛋白的氨基酸序列显示出显着的同源性。我们使用 frxC 和 nifH 特异性探针从固氮蓝细菌 Plectonema boryanum 中克隆了 frxC 和 nifH 基因，并确定了它们的核苷酸序列。从P.boryanum的frxC基因推导的氨基酸序列与地钱的frxC基因编码的蛋白质具有83％的同源性，而与来自同一生物体(即P.boryanum)的nifH基因编码的蛋白质仅表现出34％的同源性。 Northern印迹分析表明，frxC基因在固氮酶抑制条件下比在固氮酶诱导条件下转录更加活跃，这表明FrxC蛋白具有不同于固氮的功能。这些结果以及nifH和frxC基因之间的系统发育关系表明，frxC和nifH基因源自共同的祖先基因，但已经独立进化以编码具有不同功能的蛋白质。
The frxC gene, found in liverwort chloroplast DNA, encodes a protein of unknown function. The deduced amino acid sequence of the protein shows significant homology to that of nitrogenase Fe-protein encoded by the nifH gene. We have cloned the frxC and nifH genes from the nitrogen-fixing cyanobacterium Plectonema boryanum, using frxC- and nifH-specific probes, and have determined their nucleotide sequences. The amino acid sequence deduced from the frxC gene of P. boryanum exhibits 83% homology to that of the protein encoded by the frxC gene from liverwort, whereas it exhibits only 34% homology to that encoded by the nifH gene from the same organism, namely, P. boryanum. Northern blot analysis showed that the frxC gene was transcribed more actively under nitrogenase-repressed conditions than under nitrogenase-induced conditions, suggesting that the FrxC protein has a function distinct from nitrogen fixation. These results, together with the phylogenetic relationship between the nifH and frxC genes, indicate that the frxC and nifH genes are derived from a common ancestral gene but have evolved independently to encode proteins with different functions.