Spectroscopic evidence for a 5-coordinate oxygenic ligated high spin ferric heme moiety in the Neisseria meningitidis hemoglobin binding receptor.
Spectroscopic evidence for a 5-coordinate oxygenic ligated high spin ferric heme moiety in the Neisseria meningitidis hemoglobin binding receptor.
复制标题
脑膜炎奈瑟菌血红蛋白结合受体中 5 配位含氧连接的高自旋铁血红素部分的光谱证据。
DOI：
10.1016/j.bbagen.2014.06.009
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Lanzilotta,WilliamN
中科院分区：
文献类型：
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作者：
Mokry,DavidZ;Nadia-Albete,Angela;Johnson,MichaelK;Lukat-Rodgers,GudrunS;Rodgers,KentonR;Lanzilotta,WilliamN
背景对于许多病原微生物来说，铁的获取是哺乳动物宿主定植过程中的一个重要压力。在这种环境中，血红素是可溶铁最丰富的单一来源。虽然铁同化对于几乎所有生物的重要性是显而易见的，但许多细菌病原体获取和利用血红素的机制仍不清楚，即使是那些最常见的感染部位的细菌也是如此。方法通过电子吸收、圆二色、电子顺磁共振和共振拉曼技术，从病原体脑膜炎奈瑟氏菌获得和纯化外膜血红蛋白受体(HMBR)的替代方案，促进了这种外膜转运蛋白的生物物理特征。血红素结合位置容纳了外源咪唑作为第六配体，这导致了六配位、低自旋的铁物种。5配位和6配位的配合物均被亚硫酸钠还原。已发现四个与血红素结合效率略有下降的HMBR变体(H87C、H280A、Y282A和Y456C)。结论本研究首次为脑膜炎奈瑟氏菌的血红素或铁转运体提供了光谱特征，并提出了迄今为止在TonB依赖的氯化血红素转运体中未观察到的配位环境。脑膜炎为新的抗菌策略提供了基础。
BackgroundFor many pathogenic microorganisms, iron acquisition represents a significant stress during the colonization of a mammalian host. Heme is the single most abundant source of soluble iron in this environment. While the importance of iron assimilation for nearly all organisms is clear, the mechanisms by which heme is acquired and utilized by many bacterial pathogens, even those most commonly found at sites of infection, remain poorly understood.MethodsAn alternative protocol for the production and purification of the outer membrane hemoglobin receptor (HmbR) from the pathogen Neisseria meningitidis has facilitated a biophysical characterization of this outer membrane transporter by electronic absorption, circular dichroism, electron paramagnetic resonance, and resonance Raman techniques.ResultsHmbR co-purifies with 5-coordinate high spin ferric heme bound. The heme binding site accommodates exogenous imidazole as a sixth ligand, which results in a 6-coordinate, low-spin ferric species. Both the 5- and 6-coordinate complexes are reduced by sodium hydrosulfite. Four HmbR variants with a modest decrease in binding efficiency for heme have been identified (H87C, H280A, Y282A, and Y456C). These findings are consistent with an emerging paradigm wherein the ferric iron center of bound heme is coordinated by a tyrosine ligand.ConclusionIn summary, this study provides the first spectroscopic characterization for any heme or iron transporter inNeisseria meningitidis, and suggests a coordination environment heretofore unobserved in a TonB-dependent hemin transporter.General SignificanceA detailed understanding of the nutrient acquisition pathways in common pathogens such asN. meningitidisprovides a foundation for new antimicrobial strategies.