Adaptive response of Amphibacillus xylanus to normal aerobic and forced oxidative stress conditions
Adaptive response of Amphibacillus xylanus to normal aerobic and forced oxidative stress conditions
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DOI：
10.1099/mic.0.068726-0
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发表时间：
2014-02-01
期刊：
影响因子：
2.8
通讯作者：
Niimura, Youichi
中科院分区：
文献类型：
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作者：
Mochizuki, Daichi;Arai, Toshiaki;Niimura, Youichi
在好氧和厌氧条件下，木Amphibacillus xylanus以相同的速率和相同的细胞产量生长。在有氧条件下，尽管缺乏呼吸系统和血红素过氧化氢酶，它仍表现出旺盛的耗氧量。为了解木霉对氧化胁迫的适应性反应，对木霉进行了基因组分析。分析结果表明，木霉具有2个丙酮酸代谢途径、1个糖酵解代谢途径和1个NADH氧化酶(Nox)-AhpC （Prx）系统4个代谢系统的基因。一项转录研究证实木霉具有这些代谢系统。此外，基因组分析显示存在两个NADH氧化酶基因（nox1和nox2），这两个基因都在转录分析中被鉴定出来。木霉nox1基因在正常有氧条件下高表达，而nox2基因不高表达。NADH氧化酶的纯化研究表明，nox1的基因产物是一种主要的代谢酶，负责氧和活性氧的代谢。在0.1 mM H2O2、0.3 mM百草枯和80%氧气的强制氧化应激条件下，木芽草成功生长。蛋白质组学分析表明，锰SOD、Prx、丙酮酸脱氢酶复合体E1和E3组分以及核黄素合成酶β链在正常好氧条件下被诱导，除5种好氧诱导蛋白外，其他蛋白在强制氧化应激条件下无诱导作用。综上所述，目前的研究结果表明木霉具有独特的防御系统来抵抗强迫氧化应激。
Amphibacillus xylanus grows at the same rate and with the same cell yield under aerobic and anaerobic conditions. Under aerobic conditions, it exhibits vigorous oxygen consumption in spite of lacking a respiratory system and haem catalase. To understand the adaptive response of A. xylanus to oxidative stresses, a genomic analysis of A. xylanus was conducted. The analysis showed that A. xylanus has the genes of four metabolic systems: two pyruvate metabolic pathways, a glycolytic metabolic pathway and an NADH oxidase (Nox)-AhpC (Prx) system. A transcriptional study confirmed that A. xylanus has these metabolic systems. Moreover, genomic analysis revealed the presence of two genes for NADH oxidase (nox1 and nox2), both of which were identified in the transcriptional analysis. The nox1 gene in A. xylanus was highly expressed under normal aerobic conditions but that of nox2 was not. A purification study of NADH oxidases indicated that the gene product of nox1 is a primary metabolic enzyme responsible for metabolism of both oxygen and reactive oxygen species. A. xylanus was successfully grown under forced oxidative stress conditions such as 0.1 mM H2O2, 0.3 mM paraquat and 80% oxygen. Proteomic analysis revealed that manganese SOD, Prx, pyruvate dehydrogenase complex E1 and E3 components, and riboflavin synthase beta-chain are induced under normal aerobic conditions, and the other proteins except the five aerobically induced proteins were not induced under forced oxidative stress conditions. Taken together, the present findings indicate that A. xylanus has a unique defence system against forced oxidative stress.