Kaminski P A, Elmerich C
Département des Biotechnologies, Institute Pasteur, Paris, France.
Mol Microbiol. 1991 Mar;5(3):665-73. doi: 10.1111/j.1365-2958.1991.tb00738.x.
A gene bank of Azorhizobium caulinodans DNA constructed in the bacteriophage lambda GEM11 was screened with Rhizobium meliloti fixL and fixJ genes as probes. One positive recombinant phage, ORS lambda L, was isolated. The nucleotide sequence of a 3.7 kb fragment was established. Two open reading frames of 1512bp and 613bp were identified as fixL and fixJ. Kanamycin cartridges were inserted into the cloned fixL and fixJ genes and recombined into the host genome. The resulting mutants were Nif- Fix-, suggesting that the two genes were required for symbiotic nitrogen fixation and for nitrogen fixation in the free-living state. Using pnifH-lacZ and pnifA-lacZ fusions, it was shown that the FixLJ products controlled the expression of nifH and nifA in bacteria grown in the free-living state.
以苜蓿根瘤菌（Rhizobium meliloti）的fixL和fixJ基因为探针，对构建于噬菌体λ GEM11中的茎瘤固氮根瘤菌（Azorhizobium caulinodans）DNA基因文库进行筛选。分离得到一个阳性重组噬菌体ORSλL。确定了一个3.7kb片段的核苷酸序列。两个分别为1512bp和613bp的开放阅读框被鉴定为fixL和fixJ。将卡那霉素盒插入克隆的fixL和fixJ基因中，并重组到宿主基因组中。所得突变体为固氮缺陷型和固氮调节缺陷型，表明这两个基因是共生固氮和自由生活状态下固氮所必需的。使用pnifH - lacZ和pnifA - lacZ融合体表明，FixLJ产物在自由生活状态下生长的细菌中控制nifH和nifA的表达。
