A quinol oxidase, encoded by cyoABCD, is utilized to adapt to lower O2 concentrations in Rhizobium etli CFN42.
A quinol oxidase, encoded by cyoABCD, is utilized to adapt to lower O2 concentrations in Rhizobium etli CFN42.
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DOI：
10.1099/mic.0.083386-0
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发表时间：
2015-01
期刊：
影响因子：
--
通讯作者：
Noel KD
中科院分区：
文献类型：
--
作者：
Lunak ZR;Noel KD
细菌有分支的需氧呼吸链，终止于不同的末端氧化酶。这些末端氧化酶具有不同的性质，例如它们对氧的亲和力、转录调节和质子泵送能力。本研究的重点是由cyoABCD编码的醌醇氧化酶。虽然这种氧化酶（Cyo）在细菌中广泛存在，但对其在细胞中的作用知之甚少，特别是在含有细胞色素c氧化酶和醌醇氧化酶的细菌中。使用Rhizobium etli CFN 42作为模式生物，分析cyo突变体在高（21%O2）和低（1和0.1%O2）环境氧浓度下在分批培养物中生长的能力。 与其他氧化酶突变体相比，cyo突变体在低氧条件下具有明显更长的滞后期。使用cyo：：lacZ转录融合物，显示野生型中的cyo表达在1和2.5%O2之间达到峰值。 此外，定量逆转录酶PCR显示，与完全有氧（21% O2）条件相比，cyoB在1% O2中上调约5倍。 在与菜豆共生过程中对Cyo突变体的分析表明，Cyo在共生的早期发展过程中被利用。虽然通常认为Cyo仅在较高的氧浓度下使用，但本研究的结果表明Cyo对低氧下的适应和持续生长很重要。
Bacteria have branched aerobic respiratory chains that terminate at different terminal oxidases. These terminal oxidases have varying properties such as their affinity for oxygen, transcriptional regulation and proton pumping ability. The focus of this study was a quinol oxidase encoded by cyoABCD. Although this oxidase (Cyo) is widespread among bacteria, not much is known about its role in the cell, particularly in bacteria that contain both cytochrome c oxidases and quinol oxidases. Using Rhizobium etli CFN42 as a model organism, a cyo mutant was analysed for its ability to grow in batch cultures at high (21 % O2) and low (1 and 0.1 % O2) ambient oxygen concentrations. In comparison with other oxidase mutants, the cyo mutant had a significantly longer lag phase under low-oxygen conditions. Using a cyo :: lacZ transcriptional fusion, it was shown that cyo expression in the wild type peaks between 1 and 2.5 % O2. In addition, it was shown with quantitative reverse transcriptase PCR that cyoB is upregulated approximately fivefold in 1 % O2 compared with fully aerobic (21 % O2) conditions. Analysis of the cyo mutant during symbiosis with Phaseolous vulgaris indicated that Cyo is utilized during early development of the symbiosis. Although it is commonly thought that Cyo is utilized only at higher oxygen concentrations, the results from this study indicate that Cyo is important for adaptation to and sustained growth under low oxygen.
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