Nuclear magnetic resonance and infrared spectroscopy have been used to investigate the formation of complexes of BAL30072 with Fe3+ and Ga3+ in solution and to collect geometrical parameters supporting reliable 3D structure models. Structural models for the ligand-metal complexes with different stoichiometries have been characterized using density functional theory calculations. Blind ensemble docking to the PiuA receptor from P. aeruginosa was performed for the different complexes to compare binding affinities and statistics of the residues most frequently contacted. When compared to analogues, BAL30072 was found to have an intrinsic propensity to form complexes with low ligand-to-metal stoichiometry. By using one of the sulfate oxygen atoms as a third donor in addition to the bidentate pyridinone moiety, BAL30072 can form a L2M complex, which was predicted to be the one with the best binding affinity to PiuA. The example of BAL30072 strongly suggests that a lower stoichiometry might be the one recognized by the receptor, so that to focus only on the highest stoichiometry might be misleading for siderophores with less than six donors.

中文翻译：

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由铁载体的单磺内酰胺抗生素BAL30072形成的复合物及其与铜绿假单胞菌的外膜受体PiuA的相互作用。

核磁共振和红外光谱已用于研究BAL30072与溶液中Fe3 +和Ga3 +的配合物的形成，并收集支持可靠3D结构模型的几何参数。使用密度泛函理论计算已表征了具有不同化学计量比的配体-金属配合物的结构模型。对铜绿假单胞菌的PiuA受体进行了盲合对接，以比较不同的复合物，以比较结合亲和力和最常接触的残基的统计数据。当与类似物比较时，发现BAL30072具有形成具有低配体-金属化学计量比的配合物的固有倾向。通过使用硫酸盐氧原子之一作为除双齿吡啶酮部分之外的第三种供体，BAL30072可以形成L2M配合物 预计它是与PiuA结合力最好的一种。BAL30072的例子强烈表明，较低的化学计量可能是受体识别的，因此仅关注最高化学计量可能会误导供体少于六个的铁载体。