Punchi Hewage Achala N D, Fontenot Leo, Guidry Jessie, Weldeghiorghis Thomas, Mehta Anil K, Donnarumma Fabrizio, Rivera Mario
Department of Chemistry, University of Kansas, 2030 Becker Dr., Lawrence, KS 66047, USA.
Department of Chemistry, Louisiana State University, 232 Choppin Hall, Baton Rouge, LA 70803, USA.
Pathogens. 2020 Nov 24;9(12):980. doi: 10.3390/pathogens9120980.
Iron homeostasis offers a significant bacterial vulnerability because pathogens obtain essential iron from their mammalian hosts, but host-defenses maintain vanishingly low levels of free iron. Although pathogens have evolved mechanisms to procure host-iron, these depend on well-regulated iron homeostasis. To disrupt iron homeostasis, our work has targeted iron mobilization from the iron storage protein bacterioferritin (BfrB) by blocking a required interaction with its cognate ferredoxin partner (Bfd). The blockade of the BfrB-Bfd complex by deletion of the gene (Δ) causes iron to irreversibly accumulate in BfrB. In this study we used mass spectrometry and NMR spectroscopy to compare the proteomic response and the levels of key intracellular metabolites between wild type (wt) and isogenic Δ strains. We find that the irreversible accumulation of unusable iron in BfrB leads to acute intracellular iron limitation, even if the culture media is iron-sufficient. Importantly, the iron limitation and concomitant iron metabolism dysregulation trigger a cascade of events that lead to broader metabolic homeostasis disruption, which includes sulfur limitation, phenazine-mediated oxidative stress, suboptimal amino acid synthesis and altered carbon metabolism.
铁稳态为细菌提供了一个重要的脆弱点，因为病原体从其哺乳动物宿主中获取必需的铁，而宿主防御机制会将游离铁的水平维持在极低的水平。尽管病原体已经进化出获取宿主铁的机制，但这些机制依赖于良好调节的铁稳态。为了破坏铁稳态，我们的研究工作通过阻断铁储存蛋白细菌铁蛋白（BfrB）与其同源铁氧化还原蛋白伴侣（Bfd）之间的必需相互作用，来靶向铁从细菌铁蛋白的动员。通过缺失 基因（Δ）来阻断BfrB - Bfd复合物，会导致铁不可逆地在BfrB中积累。在这项研究中，我们使用质谱和核磁共振光谱来比较野生型（wt）和同基因Δ菌株之间的蛋白质组学反应以及关键细胞内代谢物的水平。我们发现，即使培养基中铁充足，BfrB中不可用铁的不可逆积累也会导致急性细胞内铁限制。重要的是，铁限制和随之而来的铁代谢失调引发了一系列事件，导致更广泛的代谢稳态破坏，其中包括硫限制、吩嗪介导的氧化应激、次优氨基酸合成和碳代谢改变。
