Structural basis for the high thermal stability and optimum pH of sphingomyelinase C from Streptomyces griseocarneus
Structural basis for the high thermal stability and optimum pH of sphingomyelinase C from Streptomyces griseocarneus
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DOI：
10.1016/j.jbiosc.2020.09.005
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发表时间：
2021-01-01
影响因子：
2.8
通讯作者：
Sugimori, Daisuke
中科院分区：
文献类型：
--
作者：
Fujisawa, Ikuhide;Hamana, Hiroaki;Sugimori, Daisuke
鞘磷脂酶 C (SMC) 将鞘磷脂水解为神经酰胺和磷酸胆碱。原核 SMC 与哺乳动物 SMC 具有序列同源性，哺乳动物 SMC 在中性 pH 下具有最适酶 pH 值。来自非致病性原核生物灰肉链霉菌的 SMC 表现出显着的酶学特征，例如比其他原核 SMC 更高的最适 pH 值和热稳定性。确定 S. griseocarneus-SMC (Sg-SMC) 的三维结构并与其他 SMC 结构进行比较，代表了一种在结构基础上阐明 Sg-SMC 独特酶学特征的有前途的策略。因此，我们通过X射线晶体学以2.0埃的分辨率测定了Sg-SMC的晶体结构。将 Sg-SMC 结构与来自伊万诺维氏李斯特菌、蜡样芽孢杆菌和金黄色葡萄球菌的其他三种结构已知的 SMC 进行比较表明，Sg-SMC 在序列上更加多样化，并且这些 SMC5 之间主链的结构差异主要位于远离活性位点的分子表面。四种 SMC 表面积的比较表明，Sg-SMC 具有最致密的结构，这可能有助于增强 Sg-SMC 的热稳定性。 SgSMC活性位点的氢键网络涉及碱性氨基酸Arg278，而其他SMC5（Ser或Asn）中的相应残基不与金属配位水分子形成氢键。 Arg278 和 Mg2+ 离子配位水分子之间形成氢键可能是 Sg-SMC 与其他 SMC 相比具有更高最佳 pH 的原因。 (C) 2020，日本生物技术协会。版权所有。
Sphingomyelinase C (SMC) hydrolyzes sphingomyelin to ceramide and phosphocholine. Prokaryotic SMCs share sequence homology with mammalian SMCs that have enzymatic pH optima at neutral pH. SMC from the nonpathogenic prokaryote Streptomyces griseocarneus shows notable enzymatic features such as higher optimum pH and thermostability than other prokaryotic SMCs. Determination of the three-dimensional structure of S. griseocarneus-SMC (Sg-SMC) and comparison with other SMC structures represents a promising strategy to elucidate the unique enzymatic features of Sg-SMC on a structural basis. Therefore, we determined the crystal structure of Sg-SMC at 2.0 angstrom resolution by X-ray crystallography. Comparison of the Sg-SMC structure with three other structurally known SMCs from Listeria ivanovii, Bacillus cereus, and Staphylococcus aureus indicated that Sg-SMC is more diverse in sequence and that structural differences in the main chain between these SMC5 are primarily located on the molecular surface distant from the active site. Comparison of the surface area of the four SMCs revealed that Sg-SMC has the most compact structure, which may contribute to the enhanced thermostability of Sg-SMC. Regarding the hydrogen bond network in the active site of SgSMC, a basic amino acid, Arg278, is involved, whereas the corresponding residue in other SMC5 (Ser or Asn) does not form hydrogen bonds with metal-coordinating water molecules. Hydrogen bond formation between Arg278 and a Mg2+ ion-coordinating water molecule may be responsible for the higher optimal pH of Sg-SMC compared to that of other SMCs. (C) 2020, The Society for Biotechnology, Japan. All rights reserved.