Protein phosphoaspartate bonds play a variety of roles. In response regulator proteins of two-component signal transduction systems, phosphorylation of an aspartate residue is coupled to a change from an inactive to an active conformation. In phosphatases and mutases of the haloacid dehalogenase (HAD) superfamily, phosphoaspartate serves as an intermediate in phosphotransfer reactions, and in P-type ATPases, also members of the HAD family, it serves in the conversion of chemical energy to ion gradients. In each case, lability of the phosphoaspartate linkage has hampered a detailed study of the phosphorylated form. For response regulators, this difficulty was recently overcome with a phosphate analog, BeF
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, which yields persistent complexes with the active site aspartate of their receiver domains. We now extend the application of this analog to a HAD superfamily member by solving at 1.5-Å resolution the x-ray crystal structure of the complex of BeF
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with phosphoserine phosphatase (PSP) from
Methanococcus jannaschii
. The structure is comparable to that of a phosphoenzyme intermediate: BeF
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is bound to Asp-11 with the tetrahedral geometry of a phosphoryl group, is coordinated to Mg
2+
, and is bound to residues surrounding the active site that are conserved in the HAD superfamily. Comparison of the active sites of BeF
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⋅PSP and BeF
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⋅CeY, a receiver domain/response regulator, reveals striking similarities that provide insights into the function not only of PSP but also of P-type ATPases. Our results indicate that use of BeF
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for structural studies of proteins that form phosphoaspartate linkages will extend well beyond response regulators.
蛋白质磷酸天冬氨酸键发挥着多种作用。在双组分信号转导系统的响应调节蛋白中,将天冬氨酸残基的磷酸化与从不活性构象转变为活性构象相耦合。在卤代酸脱卤酶(HAD)超家族的磷酸酶和突变酶中,磷酸天冬氨酸作为磷酸转移反应中的中间体,在P型ATP酶中,也是HAD家族的成员,它在化学能转化为离子梯度中起作用。在每种情况下,磷酸天冬氨酸键的不稳定性阻碍了对磷酸化形式的详细研究。对于响应调节蛋白,这一困难最近通过磷酸酯类似物BeF3-的使用得到了克服,它与其接收器结构域的活性位点天冬氨酸形成持久的复合物。我们现在通过解决BeF3-与甲烷菌PSP(磷酸丝氨酸磷酸酶)的复合物的1.5-A分辨率的X射线晶体结构来扩展这种类似物的应用于HAD超家族成员。该结构类似于磷酸酶中间体:BeF3-以磷酸酰基的四面体几何形状与Asp-11结合,与Mg2+配位,并与HAD超家族中保守的活性位点周围的残基结合。比较BeF3-·PSP和BeF3-·CeY(接收器结构域/响应调节蛋白)的活性位点揭示了惊人的相似性,这提供了对PSP和P型ATP酶功能的洞察。我们的结果表明,对于形成磷酸天冬氨酸键的蛋白质的结构研究,BeF3-的使用将远远超出响应调节蛋白的范围。