Molecular Coordination, Structure, and Stability of Metal-Polyphosphate Complexes Resolved by Molecular Modeling and X-ray Scattering: Structural Insights on the Biological Fate of Polyphosphate
Molecular Coordination, Structure, and Stability of Metal-Polyphosphate Complexes Resolved by Molecular Modeling and X-ray Scattering: Structural Insights on the Biological Fate of Polyphosphate
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通过分子建模和 X 射线散射解析金属-聚磷酸盐配合物的分子配位、结构和稳定性：对聚磷酸盐生物命运的结构见解
DOI：
10.1021/acs.est.1c04782
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发表时间：
2021
影响因子：
11.4
通讯作者：
Aristilde, Ludmilla
中科院分区：
文献类型：
--
作者：
Park, Yeonsoo;Malliakas, Christos D.;Zhou, Qing;Gu, April Z.;Aristilde, Ludmilla
聚磷菌(PAO)能够以聚磷酸盐(PolyP)的形式储存高水平的磷酸盐(PI)，被用于工程强化生物除磷(EBPR)。已有报道表明，镁和钾在PAO的息肉颗粒中共存，相对于其他金属络合物，较高的镁息肉颗粒丰度与EBPR性能稳定性呈正相关。然而，其潜在的机制仍不清楚。在这里，我们通过计算和实验技术获得了水合息肉与四种生理相关的金属离子(Na+、K+、Ca+和Mg2+)的络合物的分子结构信息。分子动力学模拟表明，镁-聚多糖和钾-聚多糖的络合物分别是最稳定的和最不稳定的，这表明这两种络合物的共存促进了不同的息肉的生物利用度。相对的热力学稳定性反映了金属络合的强度，对于镁离子，聚合配体O与金属的配位距离为1.71-2.01ä，而对于K+，该距离为2.64-2.70ä。用镁多聚物溶液获得的X射线散射数据的对分布函数分析证实了理论上的镁多聚物配位几何。这些发现暗示了金属络合作用在工程系统和自然系统中聚磷菌的磷循环特征中可能起到的机制作用。
Polyphosphate-accumulating organisms (PAOs), which can store high levels of phosphate (Pi) in the form of polyphosphate (polyP), are employed to engineer enhanced biological P removal (EBPR) from wastewaters. Co-localization of Mg and K in polyP granules of PAOs has been reported, and higher abundance of Mg-polyP granules relative to other metal complexes was correlated positively with EBPR performance stability. However, the underlying mechanism remains unknown. Here, we obtained molecular structural information of hydrated polyP complexes with four physiologically relevant metal cations (Na+, K+, Ca2+, and Mg2+) using computational and experimental techniques. Molecular dynamics simulations revealed that Mg-polyP and K-polyP complexes were the most and least stable of the complexes, respectively, suggesting that the co-occurrence of these complexes facilitates variable polyP bioavailability. The relative thermodynamic stability reflected the strength of metal chelation whereby the coordination distance between the polyP ligand O and the metal was 1.71–2.01 Å for Mg2+but this distance was 2.64–2.70 Å for K+. Pair distribution function analysis of X-ray scattering data obtained with a Mg-polyP solution corroborated the theoretical Mg-polyP coordination geometry. These findings implied a possible mechanistic role of metal complexation in the P cycling traits of PAOs in engineered and natural systems.