Abstract：
The 3\'-phosphoadenosine-5\'-phosphosulfate (PAPS) molecule is essential during enzyme-catalyzed sulfation reactions as a sulfate donor and is an intermediate in the reduction of sulfate to sulfite in the sulfur assimilation pathway. PAPS is produced through a two-step reaction involving ATP sulfurylase and adenosine 5\'-phosphosulfate (APS) kinase enzymes/domains. However, archaeal APS kinases have not yet been characterized and their mechanism of action remains unclear. Here, we first structurally characterized APS kinase from the hyperthermophilic archaeon Archaeoglobus fulgidus, (AfAPSK). We demonstrated the PAPS production activity of AfAPSK at the optimal growth temperature (83 °C). Furthermore, we determined the two crystal structures of AfAPSK: ADP complex and ATP analog adenylyl-imidodiphosphate (AMP-PNP)/Mg2+/APS complex. Structural and complementary mutational analyses revealed the catalytic and substrate recognition mechanisms of AfAPSK. This study also hints at the molecular basis behind the thermal stability of AfAPSK.
摘要：
3'-磷酸腺苷-5'-磷酸硫酸盐（PAPS）分子在酶催化的硫酸化反应中作为硫酸盐供体是必不可少的，并且是硫同化途径中硫酸盐还原为亚硫酸盐的中间体。PAPS通过涉及ATP硫酸化酶和腺苷5'-磷酸硫酸酯(APS)激酶/结构域的两步反应产生。然而,古细菌APS激酶尚未被鉴定，其作用机制尚不清楚。这里,我们首先在结构上表征了来自嗜高温古细菌古细菌的APS激酶，（AfAPSK）。我们证明了AfAPSK在最佳生长温度（83°C）下的PAPS生产活性。此外，我们确定了AfAPSK：ADP复合物和ATP类似物腺苷酰-亚氨基二磷酸（AMP-PNP）/Mg2/APS复合物的两种晶体结构。结构和互补突变分析揭示了AfAPSK的催化和底物识别机制。这项研究还暗示了AfAPSK热稳定性背后的分子基础。
