野油菜黄单胞菌中6-磷酸海藻糖合成酶注释基因的功能鉴定

Functional characterization of annotated trehalose-6-phosphate synthase gene in Xanthmonas campestris

6-磷酸海藻糖在微生物碳代谢调节及抗逆生理中起着极其重要的作用。在野油菜黄单胞菌野油菜致病变种(Xanthomonas campestris pv.campestris,Xcc)8004菌株的基因组中,XC1076注释为6-磷酸海藻糖合成酶。利用突变和表型检测技术,对XC1076进行功能鉴定,结果显示,XC1076的Tn5gusA5插入突变体006B12,在含3%NaCl的NYGB培养基中生长明显缓慢,在含葡萄糖为惟一碳源的NCM培养基中几乎不能生长,反式互补能够基本恢复野生型表型,这说明XC1076与碳代谢调控和抗高渗有关。这些表型实验结果揭示,XC1076的ORF编码的蛋白具有6-磷酸海藻糖合成酶活性。致病生化因子检测显示,XC1076与Xcc胞外酶和胞外多糖的分泌无关。

Trehalose-6-phosphate plays important role in regulation of carbon metabolism and stress tolerance in microbes. In Xanthomonas campestris pv. campestris （Xcc） 8004, XC1076 was annotated as trehalose-6-phosphate synthase. The function of XC1076 was characterized by mutagenic and phenotypic analysis. It was shown that the growth of TnSgusA5 insertion mutant of XC1076, named as 006B12, reduced significantly compared with the wild type strain 8004 in NCM medium plus different sole carbon sources and rich medium supplemented with NaCl at concentration of 3%. The transcomplementary strain restored the phenotype as wild type strain 8004. These results indicated that XC1076 was involved in regulation of carbon metabolism and played important role in resistance to high osmolarity in Xcc, hinting that protein coded by XC1076 possess activity of frehalose-6- phosphate synthase. In addition, assay of virulence biochemical factors showed that XC1076 didn＇t affect production of extracellular enzymes and exopolysaccharide in Xcc.