Transcriptional regulation of ectoine catabolism in response to multiple metabolic and environmental cues
Transcriptional regulation of ectoine catabolism in response to multiple metabolic and environmental cues
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DOI：
10.1111/1462-2920.13924
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发表时间：
2017-11-01
影响因子：
5.1
通讯作者：
Bremer, Erhard
中科院分区：
文献类型：
--
作者：
Schulz, Annina;Hermann, Lucas;Bremer, Erhard
Ectoine和hydroxyectoine是有效的微生物胁迫保护剂，但也可以作为细菌的多功能营养素。我们研究了四氢嘧啶和羟基四氢嘧啶的进口和catenylation在海洋蔷薇属物种Ruegeria pomeroyi的遗传调控，并确定了三个转录调控参与这些过程：GabR/MocR型阻遏物EnuR，盛宴和饥饿型调节AsnC和双组分系统NtrYX。相应的基因与四氢嘧啶和羟基四氢嘧啶摄取和分解代谢基因簇（enuR，asnC）以及预测消耗四氢嘧啶的微生物（ntrYX）广泛相关。EnuR含有共价结合的吡哆醛-5 '-磷酸作为辅因子，并且MocR/GabR型调节剂的功能背后的化学通常需要系统特异性低分子量效应分子。通过与纯化的EnuR的配体结合研究，我们鉴定了N-（α）-L-乙酰基-2，4-二氨基丁酸和L-2，4-二氨基丁酸作为通过四氢嘧啶催化剂产生的EnuR的诱导剂。AsnC/Lrp型蛋白质可以将DNA包裹成核小体样结构，我们发现asnC基因是使用外泌素作为营养素所必需的。此外，我们通过转座子诱变发现，NtrYX双组分系统是其催化所必需的。数据库搜索表明，我们的研究结果有重要的影响，了解大多数微生物消费者的分子生物学的ectoines。
Ectoine and hydroxyectoine are effective microbial osmostress protectants, but can also serve as versatile nutrients for bacteria. We have studied the genetic regulation of ectoine and hydroxyectoine import and catabolism in the marine Roseobacter species Ruegeria pomeroyi and identified three transcriptional regulators involved in these processes: the GabR/MocR-type repressor EnuR, the feast and famine-type regulator AsnC and the two-component system NtrYX. The corresponding genes are widely associated with ectoine and hydroxyectoine uptake and catabolic gene clusters (enuR, asnC), and with microorganisms predicted to consume ectoines (ntrYX). EnuR contains a covalently bound pyridoxal-5'-phosphate as a co-factor and the chemistry underlying the functioning of MocR/GabR-type regulators typically requires a system-specific low molecular mass effector molecule. Through ligand binding studies with purified EnuR, we identified N-(alpha)-L-acetyl-2,4-diaminobutyric acid and L-2,4-diaminobutyric acid as inducers for EnuR that are generated through ectoine catabolism. AsnC/Lrp-type proteins can wrap DNA into nucleosome-like structures, and we found that the asnC gene was essential for use of ectoines as nutrients. Furthermore, we discovered through transposon mutagenesis that the NtrYX two-component system is required for their catabolism. Database searches suggest that our findings have important ramifications for an understanding of the molecular biology of most microbial consumers of ectoines.