Ethanolamine Utilization and Bacterial Microcompartment Formation Are Subject to Carbon Catabolite Repression
Ethanolamine Utilization and Bacterial Microcompartment Formation Are Subject to Carbon Catabolite Repression
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DOI：
10.1128/jb.00703-18
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发表时间：
2019-05-01
影响因子：
3.2
通讯作者：
Garsin, Danielle A.
中科院分区：
文献类型：
--
作者：
Kaval, Karan Gautam;Gebbie, Margo;Garsin, Danielle A.
乙醇胺（EA）是一种在胃肠道（GI）中普遍存在的化合物，可用作碳源、氮源和/或能量源。粪肠球菌是一种胃肠道寄生菌和机会致病菌，含有约20个乙醇胺利用（eut）基因，编码该过程所需的调控蛋白、酶蛋白和结构蛋白。在这里，使用化学成分确定的培养基，两个调节因素，影响EA的利用进行了检查。首先，研究了小RNA（sRNA）EutX损失对EA利用功效的功能后果。观察到的一个效应是，由于这种负调节因子的丧失导致eut基因表达的增加，因此伴随着形成的分解代谢细菌微区室（BMC）的数量增加。然而，尽管这种增加，菌株的生长受到抑制，表明EA利用的总体功效受到负面影响。其次，利用缺失突变体和互补，碳分解代谢物控制蛋白A（CcpA）被证明是负责在葡萄糖的存在下EA利用的阻遏。一个预测的cre网站中的三个EA诱导型启动子，PeutS，被确定为CcpA的目标。然而，CcpA被证明间接影响所有的启动子通过双组分系统EutV和EutW，其基因的PeutS启动子的控制下的激活。此外，预测含有CcpA和cre位点的细菌的生物信息学分析显示，含有BMC的操纵子的优势可能受碳分解代谢物抑制（CCR）的调节。重要信息乙醇胺（EA）是一种常见于胃肠道（GI）的化合物，可以影响人类病原体的行为，这些病原体可以感知和利用它，如粪肠球菌和沙门氏菌。因此，重要的是要了解如何管理EA利用的基因进行调节。在这项工作中，我们研究了两个调控因素，控制这一过程。一个因素，小RNA（sRNA），被证明是重要的，以产生正确的基因表达水平，以最大限度地提高效率。第二个因子是转录抑制因子，当其他优选的能量来源可用时，它对阻止表达很重要。此外，全球生物信息学分析显示，这第二种转录调控机制可能对相关细菌中的类似基因起作用。
Ethanolamine (EA) is a compound prevalent in the gastrointestinal (GI) tract that can be used as a carbon, nitrogen, and/or energy source. Enterococcus faecalis, a GI commensal and opportunistic pathogen, contains approximately 20 ethanolamine utilization (eut) genes encoding the necessary regulatory, enzymatic, and structural proteins for this process. Here, using a chemically defined medium, two regulatory factors that affect EA utilization were examined. First, the functional consequences of loss of the small RNA (sRNA) EutX on the efficacy of EA utilization were investigated. One effect observed, as loss of this negative regulator causes an increase in eut gene expression, was a concomitant increase in the number of catabolic bacterial microcompartments (BMCs) formed. However, despite this increase, the growth of the strain was repressed, suggesting that the overall efficacy of EA utilization was negatively affected. Second, utilizing a deletion mutant and a complement, carbon catabolite control protein A (CcpA) was shown to be responsible for the repression of EA utilization in the presence of glucose. A predicted cre site in one of the three EA-inducible promoters, PeutS, was identified as the target of CcpA. However, CcpA was shown to affect the activation of all the promoters indirectly through the two-component system EutV and EutW, whose genes are under the control of the PeutS promoter. Moreover, a bioinformatics analysis of bacteria predicted to contain CcpA and cre sites revealed that a preponderance of BMC-containing operons are likely regulated by carbon catabolite repression (CCR).IMPORTANCE Ethanolamine (EA) is a compound commonly found in the gastrointestinal (GI) tract that can affect the behavior of human pathogens that can sense and utilize it, such as Enterococcus faecalis and Salmonella. Therefore, it is important to understand how the genes that govern EA utilization are regulated. In this work, we investigated two regulatory factors that control this process. One factor, a small RNA (sRNA), is shown to be important for generating the right levels of gene expression for maximum efficiency. The second factor, a transcriptional repressor, is important for preventing expression when other preferred sources of energy are available. Furthermore, a global bioinformatics analysis revealed that this second mechanism of transcriptional regulation likely operates on similar genes in related bacteria.