Alkyl hydroperoxide reductase is important for oxidative stress resistance and symbiosis in Azorhizobium caulinodans
Alkyl hydroperoxide reductase is important for oxidative stress resistance and symbiosis in Azorhizobium caulinodans
复制标题
烷基氢过氧化物还原酶对于固氮根瘤菌的氧化应激抵抗和共生很重要
DOI：
10.1093/femsle/fnz014
复制
发表时间：
2019-02-01
影响因子：
2.1
通讯作者：
Zhu, Jun
中科院分区：
文献类型：
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作者：
Jiang, Gaofei;Yang, Juan;Zhu, Jun
活性氧(ROS)不仅是有氧代谢或胁迫产生的氧的有毒产物，也是参与豆科植物-根瘤菌共生发展的信号分子。为了评估烷基过氧化氢还原酶(AhpCD)在固氮菌∆caulinodans中的重要性，我们研究了AHpCD菌株的ROS抗性和与田菁共生的表型。在对数早期，∆ahpCD菌株对过氧化氢(H_2O_2)的敏感性明显高于其亲本菌株，但对两种有机过氧化物的敏感性不明显。无论在体内还是体外，ahpCD的表达都不受LysR型转录激活剂的调控。在较低水平的H_2O_2胁迫下，∆菌株的过氧化氢酶活性受到影响。此外，∆ahpCD菌株诱导的长春花茎瘤数量减少，固氮酶活性降低。这些数据表明，主茎弧菌AhpCD不仅在体外对H_2O_2的解毒作用很重要，而且对于与长柄链霉菌的共生也是至关重要的。AhpCD的功能分析值得在其他根瘤菌中进行研究，以全面了解其对ROS防御和与豆科植物共生的贡献。
Reactive oxygen species (ROS) are not only toxic products of oxygen from aerobic metabolism or stress but also signalling molecules involved in the development of the legume-Rhizobium symbiosis. To assess the importance of alkyl hydroperoxide reductase (AhpCD) in the nitrogen-fixating bacterium Azorhizobium caulinodans, we investigated the phenotypes of the ∆ahpCD strain with regards to ROS resistance and symbiotic interactions with Sesbania rostrata. The ∆ahpCD strain was notably more sensitive than its parent strain to hydrogen peroxide (H2O2) but not to two organic peroxides, in the early log phase. The expression of ahpCD was not controlled by a LysR-type transcriptional activator either in vitro or in vivo. The catalase activity of the ∆ahpCD strain was affected at a relatively low level of H2O2 stress. Furthermore, the ∆ahpCD strain induced a reduced number of stem nodules in S. rostrata with lowering of nitrogenase activity. These data suggest that A. caulinodans AhpCD is not only important for H2O2 detoxification in vitro but also critical for symbiosis with S. rostrata. Functional analysis of AhpCD is worth investigating in other rhizobia to gain a comprehensive view of its contributions to ROS defence and symbiotic association with legumes.