Quinol oxidase encoded by cyoABCD in Rhizobium etli CFN42 is regulated by ActSR and is crucial for growth at low pH or low iron conditions.
Quinol oxidase encoded by cyoABCD in Rhizobium etli CFN42 is regulated by ActSR and is crucial for growth at low pH or low iron conditions.
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根瘤菌 CFN42 中 cyoABCD 编码的喹啉氧化酶受 ActSR 调节，对于低 pH 或低铁条件下的生长至关重要。
DOI：
10.1099/mic.0.000130
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
DaleNoel,K
中科院分区：
文献类型：
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作者：
Lunak,ZacharyR;DaleNoel,K
根瘤菌以几种末端氧化酶呼吸。由cyoABCD编码的醌醇氧化酶（Cyo）是有效适应低氧条件所必需的，并且cyo转录在低氧下被上调。本研究试图确定如何转录的调控。对cyo上游的5 '序列进行了计算机分析，揭示了ActSR双组分调节系统中ActR的推定结合位点。无论氧条件如何，cyo的表达在actSR突变体中均降低。由于已知ActSR对于另一种根瘤菌物种在低pH下的生长是重要的，因此测试了生长培养基pH对细胞表达的影响。随着培养基的pH值逐渐降低，WT中的cyo表达逐渐增加，最终在低pH值（4.8）条件下达到中性pH值（7.0）条件下的10倍高水平。在actSR突变体中，降低pH条件下的这种上调被消除。在低pH（4.8）条件下，actSR和cyomutants都有严重的生长缺陷。最后，actSR和cyomutants有严重的生长缺陷时，生长在培养基中处理的铁螯合剂。在这些条件下，cyo在WT中被上调，而cyo在actSR突变体中没有被诱导。总之，结果表明cyco表达在很大程度上依赖于ActSR双组分系统。这项研究还证明了Cyo inR的其他生理作用。etliCFN42，其中它是在酸性和低铁条件下生长的优选氧化酶。
Rhizobium etliaerobically respires with several terminal oxidases. The quinol oxidase (Cyo) encoded bycyoABCDis needed for efficient adaptation to low oxygen conditions andcyotranscription is upregulated at low oxygen. This study sought to determine how transcription of thecyooperon is regulated. The 5′ sequence upstream ofcyowas analysedin silicoand revealed putative binding sites for ActR of the ActSR two-component regulatory system. The expression ofcyowas decreased in anactSRmutant regardless of the oxygen condition. As ActSR is known to be important for growth under low pH in another rhizobial species, the effect of growth medium pH oncyoexpression was tested. As the pH of the media was incrementally decreased,cyoexpression gradually increased in the WT, eventually reaching ∼10-fold higher levels at low pH (4.8) compared with neutral pH (7.0) conditions. This upregulation ofcyounder decreasing pH conditions was eliminated in theactSRmutant. Both theactSRandcyomutants had severe growth defects at low pH (4.8). Lastly, theactSRandcyomutants had severe growth defects when grown in media treated with an iron chelator. Under these conditions,cyowas upregulated in the WT, whereascyowas not induced in theactSRmutant. Altogether, the results indicatedcyoexpression is largely dependent on the ActSR two-component system. This study also demonstrated additional physiological roles for Cyo inR. etliCFN42, in which it is the preferred oxidase for growth under acidic and low iron conditions.