Glyceraldehyde-3-phosphate dehydrogenase of Xanthomonas campestris pv. campestris is required for extracellular polysaccharide production and full virulence
Glyceraldehyde-3-phosphate dehydrogenase of Xanthomonas campestris pv. campestris is required for extracellular polysaccharide production and full virulence
复制标题
野油菜黄单胞菌 pv. 的甘油醛-3-磷酸脱氢酶。
DOI：
10.1099/mic.0.023762-0
复制
发表时间：
2009-05-01
期刊：
影响因子：
2.8
通讯作者：
Tang, Ji-Liang
中科院分区：
文献类型：
--
作者：
Lu, Guang-Tao;Xie, Jia-Ri;Tang, Ji-Liang
3-磷酸甘油醛脱氢酶在葡萄糖分解代谢中起着重要作用，它将3-磷酸甘油醛转化为1，3-二磷酸甘油酸酯。野油菜黄单胞菌基因组中的开放阅读框(ORF)XC_0972。Campestris(Xcc)菌株8004是该菌株中唯一被注释为编码GAPDH的矿石。在这项工作中，我们已经从基因上证明了该ORF编码了Xcc株8004中唯一的GAPDH，似乎是结构性表达的。突变株仍能在以葡萄糖或其他糖为唯一碳源的培养基中生长，且在8004菌株中未检测到磷酸果糖激活酶活性。这些事实表明，Xcc可能通过Entner-Doudoroff途径来利用葡萄糖，而不是糖酵解。突变体不能利用丙酮酸作为唯一碳源，而野生型可以利用丙酮酸作为唯一碳源，这表明Xcc的GAPDH参与了糖异生。此外，Xcc GAPDH的失活还会导致寄主植物中细菌生长和毒力的下降，以及胞内ATP和胞外多糖(EPS)的减少。这表明GAPDH是产生EPS和Xcc完全致病所必需的。
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) plays an important role in glucose catabolism, converting glyceraldehyde 3-phosphates to 1,3-bisphosphoglycerates. Open reading frame (ORF) XC_0972 in the genome of Xanthomonas campestris pv. campestris (Xcc) strain 8004 is the only ORE in this strain annotated to encode a GAPDH. In this work, we have demonstrated genetically that this ORF encodes a unique GAPDH in Xcc strain 8004, which seems to be constitutively expressed. A GAPDH-deficient mutant could still grow in medium with glucose or other sugars as the sole carbon source, and no phosphofructokinase activity was detectable in strain 8004. These facts suggest that Xcc may employ the Entner-Doudoroff pathway, but not glycolysis, to utilize glucose. The mutant could not utilize pyruvate as sole carbon source, whereas the wild-type could, implying that the GAPDH of Xcc is involved in gluconeogenesis. Furthermore, inactivation of the Xcc GAPDH resulted in impairment of bacterial growth and virulence in the host plant, and reduction of intracellular ATP and extracellular polysaccharide (EPS). This reveals that GAPDH is required for EPS production and full pathogenicity of Xcc.