Mechanism of the oxidative stress-mediated increase in lipid accumulation by the bacterium, R. opacus PD630: Experimental analysis and genome-scale metabolic modeling.,Biotechnology and Bioengineering

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Mechanism of the oxidative stress-mediated increase in lipid accumulation by the bacterium, R. opacus PD630: Experimental analysis and genome-scale metabolic modeling.
Biotechnology and Bioengineering ( IF 3.5 ) Pub Date : 2020-04-06 , DOI: 10.1002/bit.27330
Archanaa Sundararaghavan ₁ , Amitava Mukherjee ₂ , Swagatika Sahoo ₃ , G K Suraishkumar ₁

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Appropriate species of oleaginous bacteria, with their high growth rates and lipid accumulation capabilities, can be good contenders for industrial triacylglycerol (TAG) production, compared to microalgae. Further, oxidative stress (OS) can be used to significantly increase TAG yields in oleaginous microbes, but the mechanism is unexplored. In a first, this study explored the mechanism behind OS-mediated increase in TAG accumulation by the bacterium, Rhodococccus opacus PD630, through experimental analysis and metabolic modelling. Two mechanisms that could increase acetyl-CoA (TAG-precursor) levels were hypothesized based on literature information. One was OS-mediated inactivation of the aconitase (TCA cycle), and another was the inactivation of the triosephosphate isomerase (TPI; glycolysis). The results negated the involvement of aconitase in increased acetyl-CoA levels. Analysis of the metabolic model showed that inactivation of TPI, re-routed the flux through the pentose phosphate pathway (PPP), supplying both NADPH and acetyl-CoA for TAG synthesis. Additionally, inactivation of TPI increased TAG flux by 143%, whereas, inactivating both TPI and aconitase, increased it by 152%. We present experimental evidence for OS-mediated decrease in TPI activity and increase in activity of glucose-6-phosphate dehydrogenase (PPP enzyme). The findings indicate that increased flux through PPP can be explored to improve TAG accumulation on a large-scale.

中文翻译：

氧化应激介导的细菌脂质积累增加的机制，R. opacus PD630：实验分析和基因组规模代谢建模。

与微藻相比，适当种类的产油细菌具有高生长率和脂质积累能力，可以成为工业三酰甘油 (TAG) 生产的良好竞争者。此外，氧化应激 (OS) 可用于显着增加含油微生物的 TAG 产量，但其机制尚未探索。首先，本研究通过实验分析和代谢建模探索了 OS 介导的细菌 Rhodococccus opacus PD630 TAG 积累增加背后的机制。根据文献信息假设了两种可能增加乙酰辅酶 A（TAG 前体）水平的机制。一种是 OS 介导的乌头酸酶失活（TCA 循环），另一种是磷酸丙糖异构酶（TPI；糖酵解）的失活。结果否定了乌头酸酶在乙酰辅酶A水平增加中的作用。代谢模型的分析表明，TPI 的失活使流量重新通过磷酸戊糖途径 (PPP)，为 TAG 合成提供 NADPH 和乙酰辅酶 A。此外，TPI 的失活使 TAG 通量增加了 143%，而 TPI 和乌头酸酶的失活使 TAG 通量增加了 152%。我们提供了 OS 介导的 TPI 活性降低和葡萄糖 6-磷酸脱氢酶（PPP 酶）活性增加的实验证据。研究结果表明，可以探索增加通过 PPP 的通量以改善 TAG 的大规模积累。为 TAG 合成提供 NADPH 和乙酰辅酶 A。此外，TPI 的失活使 TAG 通量增加了 143%，而 TPI 和乌头酸酶的失活使 TAG 通量增加了 152%。我们提供了 OS 介导的 TPI 活性降低和葡萄糖 6-磷酸脱氢酶（PPP 酶）活性增加的实验证据。研究结果表明，可以探索增加通过 PPP 的通量以改善 TAG 的大规模积累。为 TAG 合成提供 NADPH 和乙酰辅酶 A。此外，TPI 的失活使 TAG 通量增加了 143%，而 TPI 和乌头酸酶的失活使 TAG 通量增加了 152%。我们提供了 OS 介导的 TPI 活性降低和葡萄糖 6-磷酸脱氢酶（PPP 酶）活性增加的实验证据。研究结果表明，可以探索增加通过 PPP 的通量以改善 TAG 的大规模积累。

更新日期：2020-04-06

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