Crawford M J, Goldberg D E
Howard Hughes Medical Institute, Departments of Medicine and Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
J Biol Chem. 1998 May 15;273(20):12543-7. doi: 10.1074/jbc.273.20.12543.
Hemoglobin homologs are being identified in an expanding number of unicellular prokaryotic and eukaryotic organisms. Many of these hemoglobins are twodomain proteins that possess a flavin-containing reductase in their C terminus. Determination of a function for these flavohemoglobins has been elusive. A Salmonella typhimurium strain harboring a deletion in the flavohemoglobin gene shows no difference in growth under oxidative stress conditions but displays an increased sensitivity to acidified nitrite and S-nitrosothiols, both of which produce nitric oxide. The effect is seen aerobically or anaerobically, indicating that oxygen is not required for flavohemoglobin function. These results suggest a role for the bacterial flavohemoglobins that is independent of oxygen metabolism and provide evidence for a bacterial route of protection from nitric oxide that is distinct from oxidative stress responses.
在越来越多的单细胞原核生物和真核生物中，血红蛋白同源物正不断被发现。其中许多血红蛋白是双结构域蛋白，其C端含有一个含黄素的还原酶。确定这些黄素血红蛋白的功能一直颇具难度。一株鼠伤寒沙门氏菌，其黄素血红蛋白基因发生了缺失，在氧化应激条件下生长并无差异，但对酸化亚硝酸盐和S -亚硝基硫醇的敏感性增加，这两种物质都会产生一氧化氮。无论是在需氧还是厌氧条件下都能观察到这种效应，这表明黄素血红蛋白发挥功能并不需要氧气。这些结果表明细菌黄素血红蛋白具有独立于氧代谢的作用，并为细菌抵御一氧化氮的途径提供了证据，该途径不同于氧化应激反应。
