Department of Biology, University of York, Heslington, York, YO10 5DD, UK.
Biochem J. 2012 Jul 1;445(1):69-79. doi: 10.1042/BJ20111984.
The closely related pathogenic Neisseria species N. meningitidis and N. gonorrhoeae are able to respire in the absence of oxygen, using nitrite as an alternative electron acceptor. aniA (copper-containing nitrite reductase) is tightly regulated by four transcriptional regulators: FNR (fumarate and nitrate reductase), NarP, FUR (Ferric uptake regulator) and NsrR. The four regulators control expression of aniA in N. meningitidis by binding to specific and distinct regions of the promoter. We show in the present study that FUR and NarP are both required for the induction of expression of aniA in N. meningitidis, and that they bind adjacent to one another in a non-co-operative manner. Activation via FUR/NarP is dependent on their topological arrangement relative to the RNA polymerase-binding site. Analysis of the sequence of the aniA promoters from multiple N. meningitidis and N. gonorrhoeae strains indicates that there are species-specific single nucleotide polymorphisms, in regions predicted to be important for regulator binding. These sequence differences alter both the in vitro DNA binding and the promoter activation in intact cells by key activators FNR (oxygen sensor) and NarP (which is activated by nitrite in N. meningitidis). The weak relative binding of FNR to the N. gonorrhoeae aniA promoter (compared to N. meningitidis) is compensated for by a higher affinity of the gonococcal aniA promoter for NarP. Despite containing nearly identical genes for catalysing and regulating denitrification, variations in the promoter for the aniA gene appear to have been selected to enable the two pathogens to tune differentially their responses to environmental variables during the aerobic-anaerobic switch.
与致病性奈瑟菌属物种关系密切的脑膜炎奈瑟菌和淋病奈瑟菌能够在缺氧的情况下呼吸，将亚硝酸盐作为替代电子受体。aniA（含铜亚硝酸盐还原酶）受四个转录调节因子的严格调控：FNR（延胡索酸和硝酸盐还原酶）、NarP、FUR（铁摄取调节剂）和 NsrR。这四个调节因子通过结合到启动子的特定和不同区域来控制 aniA 在脑膜炎奈瑟菌中的表达。在本研究中，我们表明 FUR 和 NarP 均是诱导脑膜炎奈瑟菌 aniA 表达所必需的，并且它们以非合作的方式彼此相邻结合。通过 FUR/NarP 的激活依赖于它们相对于 RNA 聚合酶结合位点的拓扑排列。来自多个脑膜炎奈瑟菌和淋病奈瑟菌菌株的 aniA 启动子序列分析表明，存在物种特异性的单核苷酸多态性，这些多态性位于预测对调节因子结合重要的区域。这些序列差异改变了关键激活因子 FNR（氧传感器）和 NarP（在脑膜炎奈瑟菌中被亚硝酸盐激活）在体外的 DNA 结合和完整细胞中的启动子激活。与脑膜炎奈瑟菌相比，FNR 对淋病奈瑟菌 aniA 启动子的相对结合较弱，但 gonococcal aniA 启动子对 NarP 的亲和力较高，从而得到补偿。尽管这两种病原体都含有几乎相同的基因来催化和调节反硝化作用，但 aniA 基因启动子的变异似乎已被选择，以使这两种病原体能够在有氧-厌氧转换过程中对环境变量的反应进行差异调节。
