The ArcBA Two-Component System of Escherichia coli Is Regulated by the Redox State of both the Ubiquinone and the Menaquinone Pool
The ArcBA Two-Component System of Escherichia coli Is Regulated by the Redox State of both the Ubiquinone and the Menaquinone Pool
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DOI：
10.1128/jb.01156-09
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发表时间：
2010-02-01
影响因子：
3.2
通讯作者：
Hellingwerf, Klaas
中科院分区：
文献类型：
--
作者：
Bekker, Martijn;Alexeeva, Svetlana;Hellingwerf, Klaas
ArcBA是大肠杆菌的一个双组分调节系统，参与感知氧的可用性以及伴随的氧化和发酵催化剂的转录调节。基于体外数据，已经假设泛醌池的氧化还原状态是ArcB激酶活性的决定因素。在这里，我们报告的ArcB激活的体内调节，确定使用lacZ报告特异性响应磷酸化的ArcA。我们的研究结果表明，在删除泛醌生物合成酶，调节ArcB在厌氧-好氧转换不受影响。相反，干扰甲基萘醌生物合成导致在厌氧生长期间ArcB失活;通过添加甲基萘醌前体，这种表型完全被拯救。这清楚地表明，甲基萘醌在ArcB激活中起着重要作用。当E.在整个需氧范围内滴定大肠杆菌; ArcB在厌氧和亚需氧条件下被激活，在完全需氧和微需氧条件下活性低得多。此外，有没有ArcB激活和泛醌池的氧化还原状态之间的相关性，但总细胞泛醌含量和ArcB活性之间的限制性相关性，由于泛醌池的大小随着有氧程度的增加而显著增加。这些结果导致工作假设，在E.大肠杆菌中的辅酶B活性受甲萘醌库的氧化还原状态的调节，体内的泛醌/泛醇比率肯定不是ArcB活性的唯一决定因素。
ArcBA is a two-component regulatory system of Escherichia coli involved in sensing oxygen availability and the concomitant transcriptional regulation of oxidative and fermentative catabolism. Based on in vitro data, it has been postulated that the redox state of the ubiquinone pool is the determinant for ArcB kinase activity. Here we report on the in vivo regulation of ArcB activation, as determined using a lacZ reporter specifically responsive to phosphorylated ArcA. Our results indicate that upon deletion of a ubiquinone biosynthetic enzyme, regulation of ArcB in the anaerobic-aerobic transition is not affected. In contrast, interference with menaquinone biosynthesis leads to inactivation of ArcB during anaerobic growth; this phenotype is fully rescued by addition of a menaquinone precursor. This clearly demonstrates that the menaquinones play a major role in ArcB activation. ArcB shows a complex pattern of regulation when E. coli is titrated through the entire aerobiosis range; ArcB is activated under anaerobic and subaerobic conditions and is much less active under fully aerobic and microaerobic conditions. Furthermore, there is no correlation between ArcB activation and the redox state of the ubiquinone pool, but there is a restricted correlation between the total cellular ubiquinone content and ArcB activity due to the considerable increase in the size of the ubiquinone pool with increasing degrees of aerobiosis. These results lead to the working hypothesis that the in vivo activity of ArcB in E. coli is modulated by the redox state of the menaquinone pool and that the ubiquinone/ubiquinol ratio in vivo surely is not the only determinant of ArcB activity.