Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, Republic of Korea.
Department of Molecular Biosciences, College of Natural Science, The University of Texas at Austin, Austin, TX, 78712, USA.
Arch Biochem Biophys. 2020 May 30;685:108350. doi: 10.1016/j.abb.2020.108350. Epub 2020 Mar 24.
Iron is an essential requirement for the survival and virulence of most bacteria. The bacterial ferrous iron transporter protein FeoB functions as a major reduced iron transporter in prokaryotes, but its biochemical mechanism has not been fully elucidated. In the present study, we compared enzymatic properties of the cytosolic portions of pathogenic bacterial FeoBs to elucidate each bacterial strain-specific characteristic of the Feo system. We show that bacterial FeoBs are classified into two distinct groups that possess either a sole GTPase or an NTPase with a substrate promiscuity. This difference in nucleotide preference alters cellular requirements for monovalent and divalent cations. While the hydrolytic activity of the GTP-dependent FeoBs was stimulated by potassium, the action of the NTP-dependent FeoBs was not significantly affected by the presence of monovalent cations. Mutation of Asn11, having a role in potassium-dependent GTP hydrolysis, changed nucleotide specificity of the NTP-dependent FeoB, resulting in loss of ATPase activity. Sequence analysis suggested a possible association of alanine in the G5 motif for the NTP-dependent activity in FeoBs. This demonstration of the distinct enzymatic properties of bacterial FeoBs provides important insights into mechanistic details of Feo iron transport processes, as well as offers a promising species-specific anti-virulence target.
铁是大多数细菌生存和毒力的必需条件。细菌亚铁转运蛋白 FeoB 作为原核生物中主要的还原铁转运蛋白，但其生化机制尚未完全阐明。在本研究中，我们比较了致病性细菌 FeoB 的胞质部分的酶学特性，以阐明 Feo 系统的每个细菌菌株特异性特征。我们表明，细菌 FeoB 分为两个截然不同的组，它们分别具有单一的 GTPase 或具有底物混杂性的 NTPase。这种核苷酸偏好的差异改变了细胞对单价和二价阳离子的需求。虽然依赖 GTP 的 FeoB 的水解活性受到钾的刺激，但依赖 NTP 的 FeoB 的作用不受单价阳离子存在的显著影响。具有钾依赖性 GTP 水解作用的 Asn11 突变改变了依赖 NTP 的 FeoB 的核苷酸特异性，导致 ATP 酶活性丧失。序列分析表明，FeoB 中的 NTP 依赖性活性的 G5 基序中存在丙氨酸的可能关联。这种对细菌 FeoB 独特酶学特性的证明为 Feo 铁转运过程的机制细节提供了重要的见解，并为有希望的物种特异性抗毒力靶标提供了可能。
