Fletcher C F, Jenkins N A, Copeland N G, Chaudhry A Z, Gronostajski R M
Mammalian Genetics Laboratory, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Frederick, Maryland 21702, USA.
Mamm Genome. 1999 Apr;10(4):390-6. doi: 10.1007/s003359901008.
The Nuclear Factor I (NFI) family of DNA-binding proteins is essential for adenovirus DNA replication and the transcription of many cellular genes. Mammals have four genes encoding NFI proteins, C. elegans has only a single NFI gene, and prokaryotes have none. To assess the relationship between members of this unusually small family of transcription/replication factors, we mapped the chromosomal locations of the four murine NFI genes and analyzed the exons encoding the DNA-binding domains of the mouse, Amphioxus, and C. elegans NFI genes. The four murine NFI genes are on Chrs 4 (Nfia and Nfib), 8 (Nfix), and 10 (Nfic), suggesting early duplication of the genes and dispersal throughout the genome. The DNA-binding domains of all four NFI genes are encoded by large (532 bp) exons with identical splice acceptor and donor sites in each. In contrast, the C. elegans nfi-1 gene has four phased introns interrupting this DNA-binding, domain-encoding exon, and the last exon extends 213 bp past the splice site used in all four murine genes. In addition, the introns present in C. elegans nfi-1 are missing from the NFI genes of Amphioxus and all mammalian genomes examined. This analysis of the exon structure of the C. elegans and murine NFI genes indicates that the murine genes were probably generated by duplication of a C. elegans-like ancestral gene, but that significant changes have occurred in the genomic organization of either the C. elegans or murine NFI genes during evolution.
核因子I（NFI）家族的DNA结合蛋白对于腺病毒DNA复制和许多细胞基因的转录至关重要。哺乳动物有四个编码NFI蛋白的基因，秀丽隐杆线虫只有一个NFI基因，而原核生物则没有。为了评估这个异常小的转录/复制因子家族成员之间的关系，我们绘制了四个小鼠NFI基因的染色体定位，并分析了编码小鼠、文昌鱼和秀丽隐杆线虫NFI基因DNA结合结构域的外显子。四个小鼠NFI基因位于第4号染色体（Nfia和Nfib）、第8号染色体（Nfix）和第10号染色体（Nfic）上，这表明这些基因早期发生了复制并分散在整个基因组中。所有四个NFI基因的DNA结合结构域均由大的（532 bp）外显子编码，每个外显子具有相同的剪接受体和供体位点。相比之下，秀丽隐杆线虫的nfi-1基因有四个相位内含子打断了这个编码DNA结合结构域的外显子，并且最后一个外显子在所有四个小鼠基因使用的剪接位点之后延伸了213 bp。此外，秀丽隐杆线虫nfi-1基因中存在的内含子在文昌鱼和所有检测的哺乳动物基因组的NFI基因中均缺失。对秀丽隐杆线虫和小鼠NFI基因外显子结构的分析表明，小鼠基因可能是由类似秀丽隐杆线虫的祖先基因复制产生的，但在进化过程中，秀丽隐杆线虫或小鼠NFI基因的基因组组织发生了显著变化。
