Hefei National Laboratory for Physical Sciences at the Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China.
Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel, UMR 5075, 41 rue Jules Horowitz, 38027 Grenoble, France.
J Biol Chem. 2011 Oct 14;286(41):35906-35914. doi: 10.1074/jbc.M111.228585. Epub 2011 Aug 23.
Spr1479 from Streptococcus pneumoniae R6 is a 33-kDa hypothetical protein of unknown function. Here, we determined the crystal structures of its apo-form at 1.90 Å and complex forms with inorganic phosphate and AMP at 2.30 and 2.20 Å, respectively. The core structure of Spr1479 adopts a four-layer αββα-sandwich fold, with Fe(3+) and Mn(2+) coordinated at the binuclear center of the active site (similar to metallophosphoesterases). Enzymatic assays showed that, in addition to phosphodiesterase activity for bis(p-nitrophenyl) phosphate, Spr1479 has hydrolase activity for diadenosine polyphosphate (Ap(n)A) and ATP. Residues that coordinate with the two metals are indispensable for both activities. By contrast, the streptococcus-specific residue Trp-67, which binds to phosphate in the two complex structures, is indispensable for the ATP/Ap(n)A hydrolase activity only. Moreover, the AMP-binding pocket is conserved exclusively in all streptococci. Therefore, we named the protein SapH for streptococcal ATP/Ap(n)A and phosphodiester hydrolase.
肺炎链球菌 R6 来源的 Spr1479 是一个 33kDa 的未知功能的假定蛋白。在此，我们解析了其无配体形式、与无机磷酸和 AMP 结合形式的晶体结构，分辨率分别为 1.90Å 和 2.30Å、2.20Å。Spr1479 的核心结构采用四层 αββα-夹心折叠，在活性位点的双核中心有 Fe(3+)和 Mn(2+)配位（类似于金属磷酸酯酶）。酶活性分析表明，Spr1479 除了具有双对硝基苯磷酸的磷酸二酯酶活性外，还具有二腺苷多磷酸（Ap(n)A）和 ATP 的水解酶活性。与两种金属配位的残基对于这两种活性都是不可或缺的。相比之下，与两种复合物结构中的磷酸结合的链霉菌特异性残基 Trp-67 对于 ATP/Ap(n)A 水解酶活性是不可或缺的。此外，AMP 结合口袋仅在所有链球菌中保守。因此，我们将该蛋白命名为 SapH，代表链球菌的 ATP/Ap(n)A 和磷酸二酯水解酶。
