Rhodes College Biology Department, 2000 North Parkway, Memphis, TN 38112, USA.
Metallomics. 2020 Nov 1;12(11):1791-1801. doi: 10.1039/d0mt00178c. Epub 2020 Oct 20.
Nitric oxide (NO˙) is a radical molecule produced by mammalian phagocytic cells as part of the innate immune response to bacterial pathogens. It exerts its antimicrobial activity in part by impairing the function of metalloproteins, particularly those containing iron and zinc cofactors. The pathogenic Gram-negative bacterium Salmonella enterica serovar typhimurium undergoes dynamic changes in its cellular content of the four most common metal cofactors following exposure to NO˙ stress. Zinc, iron and magnesium all decrease in response to NO˙ while cellular manganese increases significantly. Manganese acquisition is driven primarily by increased expression of the mntH and sitABCD transporters following derepression of MntR and Fur. ZupT also contributes to manganese acquisition in response to nitrosative stress. S. Typhimurium mutants lacking manganese importers are more sensitive to NO˙, indicating that manganese is important for resistance to nitrosative stress.
一氧化氮(NO˙)是哺乳动物吞噬细胞产生的一种自由基分子,作为先天免疫反应的一部分,对细菌病原体产生作用。它通过损害金属蛋白酶的功能来发挥其抗菌活性,特别是那些含有铁和锌辅因子的蛋白酶。致病性革兰氏阴性细菌鼠伤寒沙门氏菌在暴露于 NO˙应激后,其细胞内四种最常见金属辅因子的含量会发生动态变化。锌、铁和镁都因 NO˙而减少,而细胞内锰的含量则显著增加。锰的获取主要是由于 MntR 和 Fur 去阻遏后 mntH 和 sitABCD 转运体的表达增加所致。ZupT 也有助于对硝化应激的锰获取。缺乏锰转运体的鼠伤寒沙门氏菌突变体对 NO˙更敏感,表明锰对抵抗硝化应激很重要。