野油菜黄单胞菌野油菜致病变种8004菌株wxcA基因与EPS的产量有关  

The Gene wxcA of Xanthomonas campestris pv.campestris 8004 Strain Involved in EPS Yield

作　　者：陆光涛[1] 唐纪良[1] 危广宁[1] 何勇强[1] 陈保善[1] 

机构地区：[1]广西大学分子遗传研究所,南宁530005

出　　处：《生物工程学报》2004年第4期477-483,共7页Chinese Journal of Biotechnology

基　　金：国家自然科学基金重点资助项目 (NO .3 0 13 0 0 10 )~~

摘　　要：在以前的工作中 ,采用转座子Tn5gusA5对野油菜黄单胞菌野油菜致病变种 (Xcc) 80 0 4菌株进行诱变 ,获得一批胞外多糖 (EPS)合成减少的突变体 ,对这些突变体的Tn5gusA5的插入位点进行分析后 ,发现有两株突变体是wxcA基因不同插入位点的突变体。以前认为wxcA基因与脂多糖 (LPS)的O 抗原合成有关而与EPS的合成无关。为明确wxcA基因的功能 ,对 80 0 4菌株的wxcA基因进行缺失 ,获得的ΔwxcA突变体的EPS产量与野生型菌株相比 ,减少了 5 0 % ,并且一段PCR合成的包含wxcA基因的DNA片段能反式互补ΔwxcA突变体 ,恢复突变体的EPS产量。这证实了 80 0Xanthomonas campestris pv. campestris(Xcc ),the pathogenic agent of black rot disease in cruciferous plants, produces large amount of extracellular polysaccharide(EPS), which has found wide applications in industry. For the great commercial value of the xanthan gum , many of the genes involved in EPS biosynthesis have been cloned and the mechanism of EPS biosynthesis also has been studied. In order to clone genes involved in EPS biosynthesis, Xcc wild type strain 8004 was mutagenized with transposon Tn5 gusA 5, and a number of EPS defective mutants were isolated in our previous work. The Tn5 gusA 5 inserted sites of these mutants were located by using thermal asymmetric interlaced PCR, and results showed that two EPS defective mutants were insertion mutants of the gene wxcA which involved in lipopolysaccharide (LPS) biosynthesis. The gene wxcA involved in lipopolysaccharide biosynthesis but dose not extracellular polysaccharide in others' report. wxcA ∷Tn5 gusA 5 mutant 021C12, the polar mutant, was complemented with recombinant plasmid pLATC8570 harboring an intact wxcA gene in this work, but the yield of EPS of the wxcA ∷Tn5 gusA 5 mutant was not restored. In order to identify the function of wxcA gene of Xcc 8004 strain, the gene wxcA was deleted by gene replacement strategy, and the no polar mutant of wxcA was obtained. Δ wxcA mutant strain, named Xcc 8570, was confirmed by using both PCR and southern analysis. Beside the LPS biosynthesis of Δ wxcA mutant was affected, The EPS yield of Δ wxcA mutant strain reduced by 50% as compared with the wild type strain 8004.Δ wxcA mutant could be complemented in trans with the intact wxcA gene, and the EPS yield of the mutant was restored. The combined data showed that wxcA gene not only involved in LPS biosynthesis but also EPS yield in Xcc 8004 strain.

关 键 词：野油菜黄单胞菌野油菜致病变种 wxcA基因 胞外多糖 

分 类 号：S435.65[农业科学—农业昆虫与害虫防治]