Kim Y M, Ahn K J, Beppu T, Uozumi T
Mol Gen Genet. 1986 Nov;205(2):253-9. doi: 10.1007/BF00430436.
The complete nucleotide sequence of the regulatory operon nifLA of a nitrogen fixer Klebsiella oxytoca NG13 was determined, and the transcriptional start point was assigned by S1 mapping. The nifL protein (a repressor) was coded by an open reading frame of 1,485 bases, corresponding to a protein of 495 amino acids with a calculated molecular weight of 55,242. The open reading frame (1,572 bases) of the nifA protein (an activator), corresponding to a molecular weight of 58,649, was confirmed by in vitro transcription-translation experiments, using the wild type and artificially deleted nifA genes. The initiation codon (ATG) of nifA overlapped the termination codon(TGA) of nifL, sharing the two bases T and G. A conserved DNA contact point [Gln-(X)3-Ala-(X)3-Gly-(X)5-Val] common in many DNA binding proteins was found in the C-terminal region of the nifA sequence. The promoter sequences of nifLA, nifB and nifF in K. oxytoca coincided exactly with those of K. pneumoniae in the consensus regions at -12 and -26, although the overall homology in the promoter regions was 96%. Changes of four amino acids were found between the nifA coding sequences of K. oxytoca and K. pneumoniae.
测定了固氮菌产酸克雷伯氏菌NG13的调节操纵子nifLA的完整核苷酸序列，并通过S1作图确定了转录起始点。nifL蛋白（一种阻遏物）由一个1485个碱基的开放阅读框编码，对应于一个495个氨基酸的蛋白，计算分子量为55242。通过使用野生型和人工缺失的nifA基因进行体外转录-翻译实验，证实了nifA蛋白（一种激活剂）的开放阅读框（1572个碱基），其分子量为58649。nifA的起始密码子（ATG）与nifL的终止密码子（TGA）重叠，共享两个碱基T和G。在nifA序列的C端区域发现了许多DNA结合蛋白中常见的保守DNA接触点[Gln-(X)3-Ala-(X)3-Gly-(X)5-Val]。产酸克雷伯氏菌中nifLA、nifB和nifF的启动子序列在-12和-26的共有区域与肺炎克雷伯氏菌的启动子序列完全一致，尽管启动子区域的总体同源性为96%。在产酸克雷伯氏菌和肺炎克雷伯氏菌的nifA编码序列之间发现了四个氨基酸的变化。
