Chowdhury Nilkanta, Bagchi Angshuman
Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, Nadia, 741235, India.
Appl Biochem Biotechnol. 2017 Jul;182(3):1144-1157. doi: 10.1007/s12010-016-2388-x. Epub 2017 Jan 7.
Pseudomonas aeruginosa is a common opportunistic human pathogen. It generally attacks immunosuppressed patients like AIDS, cancer, cystic fibrosis, etc. The virulence of P. aeruginosa is mediated by various virulence factors. One of such potential virulence factors is HCN synthesized by HCN synthase enzyme, which is encoded by the hcnABC operon. The expressions of the genes of this operon are regulated by three transcriptional regulators, viz., LasR, ANR, and RhlR. In our previous work, we analyzed the molecular details of the functionalities of LasR. In this work, we focused on ANR. ANR is a regulatory protein which belongs to the FNR family and works in anaerobic condition. ANR binds to the promoter DNA, named ANR box, as a dimer. The dimerization of this ANR protein is regulated by FeS, an iron-sulfur cluster. This dimer of ANR (ANR-FeS/ANR-FeS) recognizes and binds the promoter DNA sequence and regulates the transcription of this hcnABC operon. Till date, the biomolecular details of the interactions of ANR dimer with the promoter DNA are not fully understood. Thus, we built the molecular model of ANR-FeS/ANR-FeS. We docked the complex with the corresponding promoter DNA region. We analyzed the mode of interactions with the promoter DNA under different conditions. Thus, we tried to analyze the functionality of the ANR protein during the expressions of the genes of the hcnABC operon. So far, this is the first report to detail the molecular mechanism of the gene expression in P. aeruginosa.
铜绿假单胞菌是一种常见的人类机会致病菌。它通常侵袭免疫抑制患者，如艾滋病患者、癌症患者、囊性纤维化患者等。铜绿假单胞菌的毒力由多种毒力因子介导。其中一种潜在的毒力因子是由HCN合酶合成的HCN，该酶由hcnABC操纵子编码。该操纵子基因的表达受三种转录调节因子调控，即LasR、ANR和RhlR。在我们之前的工作中，我们分析了LasR功能的分子细节。在这项工作中，我们聚焦于ANR。ANR是一种属于FNR家族的调节蛋白，在厌氧条件下起作用。ANR以二聚体形式与名为ANR框的启动子DNA结合。这种ANR蛋白的二聚化受铁硫簇FeS调控。ANR的这种二聚体（ANR-FeS/ANR-FeS）识别并结合启动子DNA序列，调控hcnABC操纵子的转录。迄今为止，ANR二聚体与启动子DNA相互作用的生物分子细节尚未完全明确。因此，我们构建了ANR-FeS/ANR-FeS的分子模型。我们将该复合物与相应的启动子DNA区域进行对接。我们分析了在不同条件下与启动子DNA的相互作用模式。因此，我们试图分析在hcnABC操纵子基因表达过程中ANR蛋白的功能。到目前为止，这是第一份详细阐述铜绿假单胞菌基因表达分子机制的报告。
