Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France.
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette, France
J Bacteriol. 2018 Jun 11;200(13). doi: 10.1128/JB.00129-18. Print 2018 Jul 1.
The NA amage esponse gene encodes a transcription regulator belonging to the cAMP receptor protein (CRP) family. Cells devoid of the DdrI protein exhibit a pleiotropic phenotype, including growth defects and sensitivity to DNA-damaging agents and to oxidative stress. Here, we show that the absence of the DdrI protein also confers sensitivity to heat shock treatment, and several genes involved in heat shock response were shown to be upregulated in a DdrI-dependent manner. Interestingly, expression of the CRP partially compensates for the absence of the DdrI protein. Microscopic observations of Δ mutant cells revealed an increased proportion of two-tetrad and anucleated cells in the population compared to the wild-type strain, indicating that DdrI is crucial for the completion of cell division and/or chromosome segregation. We show that DdrI is also involved in the megaplasmid MP1 stability and in efficient plasmid transformation by facilitating the maintenance of the incoming plasmid in the cell. The prediction of putative DdrI binding sites in the genome suggests that hundreds of genes, belonging to several functional groups, may be regulated by DdrI. In addition, the DdrI protein absolutely requires cAMP for binding to specific target sequences, and it acts as a dimer. All these data underline the major role of DdrI in physiology under normal and stress conditions by regulating, both directly and indirectly, a cohort of genes involved in various cellular processes, including central metabolism and specific responses to diverse harmful environments. has been extensively studied to elucidate the molecular mechanisms responsible for its exceptional ability to withstand lethal effects of various DNA-damaging agents. A complex network, including efficient DNA repair, protein protection against oxidation, and diverse metabolic pathways, plays a crucial role for its radioresistance. The regulatory networks orchestrating these various pathways are still missing. Our data provide new insights into the crucial contribution of the transcription factor DdrI for the ability to withstand harmful conditions, including UV radiation, mitomycin C treatment, heat shock, and oxidative stress. Finally, we highlight that DdrI is also required for accurate cell division, for maintenance of plasmid replicons, and for central metabolism processes responsible for the overall cell physiology.
该 NA 损伤反应基因编码一种转录调节剂，属于 cAMP 受体蛋白 (CRP) 家族。缺乏 DdrI 蛋白的细胞表现出多种表型，包括生长缺陷以及对 DNA 损伤剂和氧化应激的敏感性。在这里，我们表明 DdrI 蛋白的缺失也赋予了对热休克处理的敏感性，并且几种参与热休克反应的基因以 DdrI 依赖的方式被上调。有趣的是，CRP 的表达部分补偿了 DdrI 蛋白的缺失。对Δ突变细胞的显微镜观察显示，与野生型菌株相比，群体中出现了更多的二分体和无核细胞，表明 DdrI 对于细胞分裂和/或染色体分离的完成至关重要。我们表明，DdrI 还参与了大型质粒 MP1 的稳定性和有效质粒转化，通过促进传入质粒在细胞中的维持来实现。在基因组中预测的推定 DdrI 结合位点表明，数百个基因，属于几个功能组，可能受到 DdrI 的调节。此外，DdrI 蛋白绝对需要 cAMP 才能与特定的靶序列结合，并且它作为二聚体起作用。所有这些数据都强调了 DdrI 在正常和应激条件下在生理中的主要作用，通过直接和间接调节涉及各种细胞过程的基因群，包括中心代谢和对各种有害环境的特定反应。已经被广泛研究，以阐明其抵抗各种 DNA 损伤剂的致死作用的分子机制。一个复杂的网络，包括有效的 DNA 修复、蛋白质对氧化的保护以及各种代谢途径，对于其抗辐射能力起着至关重要的作用。协调这些各种途径的调节网络仍然缺失。我们的数据为转录因子 DdrI 对抵抗有害条件的能力提供了新的见解，包括紫外线辐射、丝裂霉素 C 处理、热休克和氧化应激。最后，我们强调 DdrI 对于准确的细胞分裂、质粒复制子的维持以及负责整体细胞生理学的中心代谢过程也是必需的。
