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从可互补紫云英根瘤菌（Ｒｈｉｚｏｂｉｕｍｈｕａｋｕｉ１０７）胞外多糖合成缺陷变种ＮＡ０３和ＮＡ１０的ｅｘｏＲ′－１１上亚克隆获得２．０ｋｂ的ＢｇｌＩ酶切片段，命名为ｐＪＢ－Ｈ７０１。ｐＪＢ－Ｈ７０１不仅可纠正变种ＮＡ０３和ＮＡ１０的胞外多糖缺陷表型，而且使两变种诱导宿主植物结瘤固氮能力恢复到野生型水平。测定了Ｒ．ｈｕａｋｕｉ１０７的糖基转移酶基因ｅｘｏＡ及其５′端上游和３′端下游的部分序列，全长１９６９ｂｐ。序列分析表明，Ｒ．ｈｕａｋｕｉ１０７ｅｘｏＡ基因全长为９８４ｂｐ，与Ｒｈｉｚｏｂｉｕｍｍｅｌｉｌｏｔｉ的ｅｘｏＡ基因ＤＮＡ序列有７３．１％的同源性。从核苷酸序列推测其蛋白分子量约为３５ｋＤ。其蛋白质氨基酸序列与Ｒ．ｍｅｌｉｌｏｔｉｅｘｏＡ基因产物ＥｘｏＡ具有６３．１％的同源性。本文还克隆了有启动子活性的ｅｘｏＡ基因的５′上游调控区，构建了ｅｘｏＡ－ｌａｃＺ转录融合子，对其表达进行了初步分析
A 2.0 kb BglI digested fragment was obtained from the subclone exoR’-11 of exogenous polysaccharides of Rhizobium huakui107 exopolysaccharide synthesis mutant NA03 and NA10 and named pJB-H701. pJB-H701 could not only correct the exopolysaccharide defective phenotypes of NA03 and NA10, but also restore the nodulation and nitrogen fixation ability of host plants to the wild type in both varieties. Measured by R. huakui107 glycosyltransferase gene exoA and its 5 ’upstream and 3’ downstream part of the sequence length of 1969bp. Sequence analysis showed that R The total length of huakui107exoA gene was 984bp, which shared 73.1% homology with the DNA sequence of exoA gene of Rhizobium meliloti. From the nucleotide sequence deduced that the molecular weight of its protein is about 35kD. Its protein amino acid sequence and R. The melilotiexoA gene product ExoA has 63.1% homology. In this study, we also cloned the 5 ’upstream regulatory region of exoA gene with promoter activity and constructed exoA-lacZ transcriptional fusion, and analyzed its expression