当前位置: X-MOL 学术Biochemistry › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Axial Heme Coordination by the Tyr-His Motif in the Extracellular Hemophore HasAp Is Critical for the Release of Heme to the HasR Receptor of Pseudomonas aeruginosa
Biochemistry ( IF 2.9 ) Pub Date : 2021-07-29 , DOI: 10.1021/acs.biochem.1c00389
Alecia T Dent 1 , Marley Brimberry 2 , Therese Albert 3 , William N Lanzilotta 2 , Pierre Moënne-Loccoz 3 , Angela Wilks 1
Affiliation  

Pseudomonas aeruginosa senses extracellular heme via an extra cytoplasmic function σ factor that is activated upon interaction of the hemophore holo-HasAp with the HasR receptor. Herein, we show Y75H holo-HasAp interacts with HasR but is unable to release heme for signaling and uptake. To understand this inhibition, we undertook a spectroscopic characterization of Y75H holo-HasAp by resonance Raman (RR), electron paramagnetic resonance (EPR), and X-ray crystallography. The RR spectra are consistent with a mixed six-coordinate high-spin (6cHS), six-coordinate low-spin (6cLS) heme configuration and an H218O exchangeable FeIII–O stretching frequency with 16O/18O and H/D isotope shifts that support a two-body Fe–OH2 oscillator with (iron-hydroxy)-like character as both hydrogen atoms are engaged in short hydrogen bond interactions with protein side chains. Further support comes from the EPR spectrum of Y75H holo-HasAp that shows a LS rhombic signal with ligand-field splitting values intermediate between those of His-hydroxy and bis-His ferric hemes. The crystal structure of Y75H holo-HasAp confirmed the coordinated solvent molecule hydrogen bonded through H75 and H83. The long-range conformational rearrangement of HasAp upon heme binding can still take place in Y75H holo-HasAp, because the intercalation of a hydroxy ligand between the heme iron and H75 allows the variant to reproduce the heme binding pocket observed in wild-type holo-HasAp. However, in the absence of a covalent linkage to the Y75 loop combined with the malleability provided by the bracketing H75 and H83 hydrogen bonds, either the hydroxy sixth ligand remains bound after complexation of Y75H holo-HasAp with HasR or rearrangement and coordination of H85 prevent heme transfer.

中文翻译:

细胞外血细胞 HasAp 中 Tyr-His 基序的轴向血红素协调对于向铜绿假单胞菌的 HasR 受体释放血红素至关重要

铜绿假单胞菌通过胞质外功能 σ 因子感知胞外血红素,该因子在血细胞全息-HasAp 与 HasR 受体相互作用时被激活。在这里,我们展示了 Y75H Holo-HasAp 与 HasR 相互作用,但无法释放血红素以进行信号传递和摄取。为了理解这种抑制作用,我们通过共振拉曼 (RR)、电子顺磁共振 (EPR) 和 X 射线晶体学对 Y75H 全息-HasAp 进行了光谱表征。RR 谱与混合六坐标高自旋 (6cHS)、六坐标低自旋 (6cLS) 血红素构型和 H 2 18 O 可交换 Fe III -O 伸缩频率一致,具有16 O/ 18支持双体 Fe-OH 2 的O 和 H/D 同位素位移具有(铁-羟基)样特征的振荡器,因为两个氢原子都与蛋白质侧链发生短氢键相互作用。进一步的支持来自 Y75H 全息-HasAp 的 EPR 光谱,该光谱显示 LS 菱形信号,配体场分裂值介于 His-羟基和双-His 铁血红素之间。Y75H holo-HasAp 的晶体结构证实了通过 H75 和 H83 键合的配位溶剂分子。在血红素结合后 HasAp 的长程构象重排仍然可以在 Y75H 全息-HasAp 中发生,因为血红素铁和 H75 之间羟基配体的插入允许变体复制在野生型全息中观察到的血红素结合口袋。有应用程序。然而,
更新日期:2021-08-24
down
wechat
bug