转座子挽救法对苜蓿中华根瘤菌与耐盐有关基因的定位

用含Tn5转座子的质粒pRL1063a诱变苜蓿中华根瘤菌(Sinorhizobium meliloti)042BM，得到盐敏感突变株042BML-2。采用转座子挽救法对Tn5插入位点两边的序列进行克隆与测序，获得了1179bp的转座子插入位点侧翼DNA序列。在GenBank中进行序列同源性和基因定位分析，结果表明：转座子插入在一个功能未知的基因内部，此基因长6270bp。研究证明：该基因与042BM的耐盐性有关，并定名为rtsC。氨基酸疏水性分析表明，在RtsC蛋白的N端有两个跨膜区，该蛋白与细菌趋化性相关蛋白的功能域有同源性。并对RtsC蛋白在苜蓿中华根瘤菌042BM耐盐性中的作用进行了讨论。

Positional Analysis of a Gene Related to Salt Tolerance in Sinorhizobium meliloti by Transposon Rescue

Salt sensitive mutant 042BML-2 was obtained by mutating Sinorhizobium meliloti 042BM with transposon Tn5 carried on the plasmid pRL1063a.By transposon rescue,a 1.179 kb of DNA sequence of S.meliloti flanking the Tn5 insertion site was obtained.The sequence similarity analysis through BLAST analysis in GenBank revealed the transposon was inserted into a functionally unknown gene,which is 6 270 bp in length,of S.meliloti,and the gene was named rtsC.This study indicated that rtsC was associated with salt tolerance in S.meliloti 042BM.Hydrophobicity profile analysis of the putative amino acid sequence showed that two predicted transmembrane domains existed in N-terminal portion of RtsC.The significance of RtsC protein in the salt-tolerance in S.meliloti was discussed.