Criticality of a conserved tyrosine residue in the SpeG protein from Escherichia coli.
Criticality of a conserved tyrosine residue in the SpeG protein from Escherichia coli.
复制标题
大肠杆菌 SpeG 蛋白中保守酪氨酸残基的重要性。
DOI：
10.1002/pro.4078
复制
发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Kuhn,MistyL
中科院分区：
文献类型：
--
作者：
Le,VanThiBich;Dang,Joseph;Lim,EeQi;Kuhn,MistyL
来自大肠杆菌的 SpeG 亚精胺/精胺 N-乙酰转移酶 (SSAT) 属于 Gcn5 相关的 N-乙酰转移酶 (GNAT) 蛋白超家族。该酶的体外表征表明，它可以乙酰化多胺精胺和亚精胺，并优先选择精胺。该酶具有保守的酪氨酸残基 (Y135)，存在于所有 SSAT 蛋白和许多 GNAT 功能亚家族中。它位于这些蛋白质活性中心的乙酰辅酶 A 附近，并被认为在一般酸/碱化学机制中充当一般酸。相比之下，之前的一项研究表明，这种残留物对于大肠杆菌来说并不重要。 coliSpeG 突变为苯丙氨酸时的酶活性。这一结果与之前的研究有很大不同，人类和小鼠 SSAT 蛋白中都有类似的残留物，这些蛋白也乙酰化精胺和亚精胺。因此，我们构建了E的几个突变体。 coliSpeG Y135 残留并测试其酶活性。我们发现这个保守的残基对于大肠杆菌确实至关重要。 coliSpeG 酶活性，并且在其他 SSAT 蛋白中可能表现相似。
The SpeG spermidine/spermineN‐acetyltransferase (SSAT) fromEscherichia colibelongs to the Gcn5‐relatedN‐acetyltransferase (GNAT) superfamily of proteins.In vitrocharacterization of this enzyme shows it acetylates the polyamines spermine and spermidine, with a preference toward spermine. This enzyme has a conserved tyrosine residue (Y135) that is found in all SSAT proteins and many GNAT functional subfamilies. It is located near acetyl coenzyme A in the active center of these proteins and has been suggested to act as a general acid in a general acid/base chemical mechanism. In contrast, a previous study showed this residue was not critical forE. coliSpeG enzymatic activity when mutated to phenylalanine. This result was quite different from previous studies with a comparable residue in the human and mouse SSAT proteins, which also acetylate spermine and spermidine. Therefore, we constructed several mutants of theE. coliSpeG Y135 residue and tested their enzymatic activity. We found this conserved residue was indeed critical forE. coliSpeG enzyme activity and may behave similarly in other SSAT proteins.