Department Chemistry & Biochemistry, Laurentian University, Sudbury, ON, Canada.
J Appl Microbiol. 2014 Jul;117(1):65-73. doi: 10.1111/jam.12497. Epub 2014 Mar 28.
To identify the molecular networks in Pseudomonas fluorescens that convey resistance to toxic concentrations of Zn, a common pollutant and hazard to biological systems.
Pseudomonas fluorescens strain ATCC 13525 was cultured in growth medium with millimolar concentrations of Zn. Enzymatic activities and metabolite levels were monitored with the aid of in-gel activity assays and high-performance liquid chromatography, respectively. As oxidative phosphorylation was rendered ineffective, the assimilation of citric acid mediated sequentially by citrate lyase (CL), phosphoenolpyruvate carboxylase (PEPC) and pyruvate phosphate dikinase (PPDK) appeared to play a key role in ATP synthesis via substrate-level phosphorylation (SLP). Enzymes generating the antioxidant, reduced nicotinamide adenine dinucleotide phosphate (NADPH) were enhanced, while metabolic modules mediating the formation of the pro-oxidant, reduced nicotinamide adenine dinucleotide (NADH) were downregulated.
Pseudomonas fluorescens reengineers its metabolic networks to generate ATP via SLP, a stratagem that allows the microbe to compensate for an ineffective electron transport chain provoked by excess Zn.
The molecular insights described here are critical in devising strategies to bioremediate Zn-polluted environments.
鉴定荧光假单胞菌中传递抗毒害浓度锌（一种常见的污染物和生物系统的危害物）能力的分子网络。
在含有毫摩尔浓度锌的生长培养基中培养荧光假单胞菌菌株 ATCC 13525。分别通过凝胶内活性测定和高效液相色谱法监测酶活性和代谢物水平。由于氧化磷酸化无效，柠檬酸通过柠檬酸裂合酶（CL）、磷酸烯醇丙酮酸羧激酶（PEPC）和丙酮酸磷酸二激酶（PPDK）依次进行同化，似乎在通过底物水平磷酸化（SLP）合成 ATP 中发挥关键作用。产生抗氧化剂还原型烟酰胺腺嘌呤二核苷酸磷酸（NADPH）的酶被增强，而介导形成促氧化剂还原型烟酰胺腺嘌呤二核苷酸（NADH）的代谢模块被下调。
荧光假单胞菌重新设计其代谢网络，通过 SLP 生成 ATP，这一策略使微生物能够补偿过量锌引起的无效电子传递链。
这里描述的分子见解对于制定生物修复锌污染环境的策略至关重要。
