Oxygen-dependent regulation of the central pathway for the anaerobic catabolism of aromatic compounds in Azoarcus sp strain CIB
Oxygen-dependent regulation of the central pathway for the anaerobic catabolism of aromatic compounds in Azoarcus sp strain CIB
复制标题
DOI：
10.1128/jb.188.7.2343-2354.2006
复制
发表时间：
2006-04-01
影响因子：
3.2
通讯作者：
Carmona, M
中科院分区：
文献类型：
--
作者：
Durante-Rodríguez, G;Zamarro, MT;Carmona, M
在反硝化偶氮菌菌株CIB中，氧在PN启动子转录调控中的作用已被研究。PN启动子控制bzd操纵子参与苯甲酸盐的厌氧分解代谢。在Azoarcus sp.菌株CIB和Escherichia coli细胞中使用P-N::lacZ翻译融合物进行的体内实验显示，对bzd分解代谢基因的转录具有氧依赖性抑制作用。P-N启动子的厌氧诱导需要大肠杆菌的皮毛，而bzd基因的氧依赖性抑制可以通过表达组成活性的Fnr*蛋白来绕过。体外实验表明，Fur与PN启动子结合的一致序列位于转录起始位点-41.5位置，与-35 box重叠，表明P属于II类fnr依赖启动子。Fur与RNA聚合酶（RNAP）相互作用，是RNAP- p - n复合物形成后转录起始的严格要求。在Azoarcus sp. CIB基因组中发现了一个同源基因acpR，该突变体不能在芳香化合物上厌氧生长，也不能驱动P- n::lacZ融合的表达，表明acpR是P启动子的同源转录激活因子。由于Azoarcus sp.菌株CIB缺乏AcpR并不影响其在非芳香族碳源上的生长，因此AcpR可以被认为是Fnr/Crp超家族的转录调节剂，该超家族已经进化到特异性控制Azoarcus中芳香族化合物厌氧分解代谢的中心途径。
The role of oxygen in the transcriptional regulation of the PN promoter that controls the bzd operon involved in the anaerobic catabolism of benzoate in the denitrifying Azoarcus sp. strain CIB has been investigated. In vivo experiments using P-N::lacZ translational fusions, in both Azoarcus sp. strain CIB and Escherichia coli cells, have shown an oxygen-dependent repression effect on the transcription of the bzd catabolic genes. E. coli Fur was required for the anaerobic induction of the P-N promoter, and the oxygen-dependent repression of the bzd genes could be bypassed by the expression of a constitutively active Fnr* protein. In vitro experiments revealed that Fur binds to the PN promoter at a consensus sequence centered at position -41.5 from the transcription start site overlapping the -35 box, suggesting that P, belongs to the class II Fnr-dependent promoters. Fur interacts with RNA polymerase (RNAP) and is strictly required for transcription initiation after formation of the RNAP-P-N complex. An fnr ortholog, the acpR gene, was identified in the genome of Azoarcus sp. strain CIB. The Azoarcus sp. strain CIB aepR mutant was unable to grow anaerobically on aromatic compounds and it did not drive the expression of the P-N::lacZ fusion, suggesting that AcpR is the cognate transcriptional activator of the P, promoter. Since the lack of AcpR in Azoarcus sp. strain CIB did not affect growth on nonaromatic carbon sources, AcpR can be considered a transcriptional regulator of the Fnr/Crp superfamily that has evolved to specifically control the central pathway for the anaerobic catabolism of aromatic compounds in Azoarcus.