Michiels J, D'hooghe I, Verreth C, Pelemans H, Vanderleyden J
F. A. Janssens Laboratory of Genetics, Catholic University of Leuven, Heverlee, Belgium.
Arch Microbiol. 1994;161(5):404-8. doi: 10.1007/BF00288950.
We report the isolation, mutational analysis and the nucleotide sequence of the Rhizobium leguminosarum bv. phaseoli nifA gene. Comparison of the deduced amino acid sequence with other NifA sequences indicated the presence of the conserved central activator and the C-terminal DNA-binding domains. Nodules elicited by a R. leguminosarum bv. phaseoli nifA mutant were symbiotically ineffective. The expression of a nifA-gusA fusion was shown to be independent on the oxygen status of the cell. We cloned the three nifH copies of R. leguminosarum bv. phaseoli and determined the nucleotide sequence of their promoter regions. The expression of nifH-gusA fusions is induced under microaerobic conditions and is dependent on the presence of NifA.
我们报道了菜豆根瘤菌（Rhizobium leguminosarum bv. phaseoli）nifA基因的分离、突变分析及核苷酸序列。将推导的氨基酸序列与其他NifA序列进行比较，表明存在保守的中央激活域和C端DNA结合域。菜豆根瘤菌nifA突变体诱导形成的根瘤在共生方面无效。nifA - gusA融合基因的表达显示出与细胞的氧状态无关。我们克隆了菜豆根瘤菌的三个nifH拷贝，并确定了它们启动子区域的核苷酸序列。nifH - gusA融合基因的表达在微需氧条件下被诱导，并且依赖于NifA的存在。
