Structural and functional insights into the Asp1/2/3 complex mediated secretion of pneumococcal serine-rich repeat protein PsrP
Structural and functional insights into the Asp1/2/3 complex mediated secretion of pneumococcal serine-rich repeat protein PsrP
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Asp1/2/3 复合物介导的肺炎球菌富含丝氨酸重复蛋白 PsrP 分泌的结构和功能见解
DOI：
10.1016/j.bbrc.2020.01.146
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发表时间：
2020-04-09
影响因子：
3.1
通讯作者：
Hou，Wen-Tao
中科院分区：
文献类型：
--
作者：
Guo，Cong;Feng，Zhang;Hou，Wen-Tao
由七个保守组件组成的辅助 sec 系统通常分布在致病性革兰氏阳性菌中，用于分泌富含丝氨酸的重复蛋白 (SRRP)。系统中的 Asp1/2/3 蛋白复合物负责 GlcNAc 的 O-乙酰化以及将 SRRP 传递至 SecA2。然而，Asp1/2/3 转运 SRRP 的分子机制仍不清楚。在这里，我们报道了肺炎链球菌的 Asp1/2/3 的复杂结构，大小为 2.9 Å。进一步的功能测定表明，Asp1/2/3 可以刺激 SecA2 的 ATPase 活性。此外，asp1/2/3基因的删除导致在突变细胞的原生质体部分中糖型改变的分泌型PsrP的积累，这表明底物的修饰/运输偶联。总之，这些发现不仅为进一步研究SRRPs的转运过程提供了结构基础，而且揭示了Asp1/2/3在辅助sec系统中不可或缺的作用。
The accessory sec system consisting of seven conserved components is commonly distributed among pathogenic Gram-positive bacteria for the secretion of serine-rich-repeat proteins (SRRPs). Asp1/2/3 protein complex in the system is responsible for both the O-acetylation of GlcNAc and delivering SRRPs to SecA2. However, the molecular mechanism of how Asp1/2/3 transport SRRPs remains unknown. Here, we report the complex structure of Asp1/2/3 fromStreptococcus pneumoniaeat 2.9 Å. Further functional assays indicated that Asp1/2/3 can stimulate the ATPase activity of SecA2. In addition, the deletion ofasp1/2/3gene resulted in the accumulation of a secreted version of PsrP with an altered glycoform in protoplast fraction of the mutant cell, which suggested the modification/transport coupling of the substrate. Altogether, these findings not only provide structural basis for further investigations on the transport process of SRRPs, but also uncover the indispensable role of Asp1/2/3 in the accessory sec system.