Intracellular free flavin and its associated enzymes participate in oxygen and iron metabolism in Amphibacillus xylanus lacking a respiratory chain.
Intracellular free flavin and its associated enzymes participate in oxygen and iron metabolism in Amphibacillus xylanus lacking a respiratory chain.
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DOI：
10.1002/2211-5463.12425
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发表时间：
2018-06
期刊：
影响因子：
2.6
通讯作者：
Niimura Y
中科院分区：
文献类型：
--
作者：
Kimata S;Mochizuki D;Satoh J;Kitano K;Kanesaki Y;Takeda K;Abe A;Kawasaki S;Niimura Y
木Amphibacillus xylanus是最近发现的一种在好氧和厌氧条件下都能很好生长的细菌，可能对生物质利用有帮助。尽管缺乏呼吸链，但木Amphibacillus xylanus消耗氧气的速度与大肠杆菌相似（在37°C下，130-140 μmol oxygen·min - 1·g - 1干细胞），这表明它有一个使用大量氧气的替代系统。以前有报道称，在外源添加的游离黄素存在的情况下，xylanus Amphibacillus NADH oxidase （Nox）能迅速降低分子氧含量。本文建立了一种利用法压法和超滤膜法测定木霉胞内游离黄素浓度的定量方法。黄素腺嘌呤二核苷酸（FAD）、黄素单核苷酸（FMN）和核黄素的细胞内浓度分别约为8 μm、3 μm和1 μm。在FAD存在的情况下，两种黄素蛋白Nox（结合FAD）和NAD(P)H氧化还原酶（Npo，结合FMN）被确定为氧代谢途径中的中心游离黄素相关酶。在游离8 μm的FAD下，重组Nox和Npo对氧的催化效率（k cat/ k m）分别提高了约5倍和9倍。木霉暴露于氧气环境后，细胞内Nox和Npo水平升高，并刺激细胞内FAD的形成。这表明这两种酶和游离FAD有助于有效的氧解毒和NAD(P)+再生，以维持好氧生长过程中的氧化还原平衡。此外，木霉需要铁来进行有氧生长。我们还讨论了游离黄素相关系统在铁利用过程中的作用。
Amphibacillus xylanus is a recently identified bacterium which grows well under both aerobic and anaerobic conditions and may prove useful for biomass utilization. Amphibacillus xylanus, despite lacking a respiratory chain, consumes oxygen at a similar rate to Escherichia coli (130–140 μmol oxygen·min−1·g−1 dry cells at 37 °C), suggesting that it has an alternative system that uses a large amount of oxygen. Amphibacillus xylanus NADH oxidase (Nox) was previously reported to rapidly reduce molecular oxygen content in the presence of exogenously added free flavin. Here, we established a quantitative method for determining the intracellular concentrations of free flavins in A. xylanus, involving French pressure and ultrafiltration membranes. The intracellular concentrations of flavin adenine dinucleotide (FAD), flavin mononucleotide (FMN), and riboflavin were estimated to be approximately 8, 3, and 1 μm, respectively. In the presence of FAD, the predominant free flavin species, two flavoproteins Nox (which binds FAD) and NAD(P)H oxidoreductase (Npo, which binds FMN), were identified as central free flavin‐associated enzymes in the oxygen metabolic pathway. Under 8 μm free FAD, the catalytic efficiency (k cat/K m) of recombinant Nox and Npo for oxygen increased by approximately fivefold and ninefold, respectively. Nox and Npo levels were increased, and intracellular FAD formation was stimulated following exposure of A. xylanus to oxygen. This suggests that these two enzymes and free FAD contribute to effective oxygen detoxification and NAD(P)+ regeneration to maintain redox balance during aerobic growth. Furthermore, A. xylanus required iron to grow aerobically. We also discuss the contribution of the free flavin‐associated system to the process of iron utilization.
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影响因子：
5.3
作者：
Ji H;Zhu Y;Tian S;Xu M;Tian Y;Li L;Wang H;Hu L;Ji Y;Ge J;Wen W;Dong H
通讯作者：
Dong H
影响因子：
3.2
作者：
Nishiyama, Y;Massey, V;Niimura, Y
通讯作者：
Niimura, Y
影响因子：
2
作者：
Maruyama, T;Higuchi, K;Tadano, T
通讯作者：
Tadano, T
影响因子：
4.8
作者：
Parry, RJ;Li, WY
通讯作者：
Li, WY
DOI：
10.1111/j.1432-1033.1993.tb17591.x
发表时间：
1993-02-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
--
作者：
COVES, J;FONTECAVE, M
通讯作者：
FONTECAVE, M