Barchini E, Cowart R E
Department of Microbiology/Immunology, Oral Roberts University School of Medicine, Tulsa, OK 74137, USA.
Arch Microbiol. 1996 Jul;166(1):51-7. doi: 10.1007/s002030050354.
Little is known about how pathogenic microorganisms that do not produce low-molecular-weight iron-chelating agents, termed siderophores, acquire iron from their environment. We have identified an extracellular enzyme produced by Listeria monocytogenes that can mobilize iron from a variety of iron-chelate complexes via reduction of the metal. The iron reductase requires Mg2+, flavin mononucleotide (FMN), and reduced nicotinamide adenine dinucleotide (NADH) for activity. Saturation kinetics were found when initial velocity studies of iron reduction were carried out as a function of variable FMN concentrations in the presence of 100 microM NADH and 10 mM Mg2+. Hyperbolic kinetics were also found when these studies were repeated as a function of variable NADH concentrations along with 20 microM FMN and 10 mM Mg2+. This process of extracellular reduction, in all likelihood, could be involved in the mobilization of iron from soils and aqueous environments and from host tissues in pathogenic processes. This is the first report of the extracellular enzymic reduction of iron by microorganisms.
对于那些不产生低分子量铁螯合剂（即铁载体）的致病微生物如何从其环境中获取铁，人们了解甚少。我们已经鉴定出一种由单核细胞增生李斯特菌产生的细胞外酶，它可以通过还原金属从多种铁螯合物复合物中动员铁。铁还原酶的活性需要Mg2+、黄素单核苷酸（FMN）和还原型烟酰胺腺嘌呤二核苷酸（NADH）。当在100 microM NADH和10 mM Mg2+存在的情况下，以可变FMN浓度为函数进行铁还原的初始速度研究时，发现了饱和动力学。当以可变NADH浓度以及20 microM FMN和10 mM Mg2+为函数重复这些研究时，也发现了双曲线动力学。在致病过程中，这种细胞外还原过程很可能参与了从土壤、水环境以及宿主组织中动员铁的过程。这是关于微生物对铁进行细胞外酶促还原的首次报道。
