Abstract

The functional activity of different phylogenetic variants of the transcriptional activator of nitrogen fixation genes in the cells of root nodule bacteria (rhizobia) of different taxa was analyzed. For this purpose, recombinant strains of root nodule bacteria of the genera Mesorhizobium, Ensifer (Sinorhizobium), and Rhizobium were created using genetic engineering constructs based on the plasmid pJN105. This plasmid contains different phylogenetic variants of the nifA gene typical for bacteria of the genera Mesorhizobium, Ensifer, and Rhizobium under the control of the ParaBAD bacterial promoter. It was shown that in free-living recombinant cells of all three bacterial genera, the introduction of an additional active copy of the nifA gene to their genome resulted in emergence of detectable nitrogenase activity. The level of nitrogenase activity was not directly related to the phylogeny of the introduced nifA gene, which is most likely explained by the universality of the product of this gene within the studied group of bacteria. The data obtained indicate the possibility of combinatorial processes in the evolution of nitrogen fixation genes.

中文翻译：

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根瘤菌群中 nifA 基因产物的功能特异性

摘要

分析了不同分类群根瘤菌（根瘤菌）细胞中固氮基因转录激活因子的不同系统发育变异体的功能活性。为此，使用基于质粒pJN105 的基因工程构建体创建了中根瘤菌、Ensifer（中华根瘤菌）和根瘤菌属的根瘤菌重组菌株。该质粒含有的不同系统发育变体nifA基因基因典型的属的细菌中慢生根瘤菌，Ensifer，和根瘤菌所述的控制下ParaBAD细菌启动子。结果表明，在所有三个细菌属的自由生活重组细胞中，将额外的nifA基因活性拷贝引入其基因组会导致出现可检测的固氮酶活性。固氮酶活性水平与引入的nifA基因的系统发育没有直接关系，这很可能是由于该基因产物在所研究的细菌组中的普遍性所致。获得的数据表明固氮基因进化中可能存在组合过程。