Stabilization of F-actin by Salmonella effector SipA resembles the structural effects of inorganic phosphate and phalloidin.
Stabilization of F-actin by Salmonella effector SipA resembles the structural effects of inorganic phosphate and phalloidin.
复制标题
沙门氏菌效应子 SipA 对 F-肌动蛋白的稳定作用类似于无机磷酸盐和鬼笔环肽的结构效应。
DOI：
10.1101/2023.12.26.573373
复制
发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Kudryashov,DmitriS
中科院分区：
文献类型：
--
作者：
Niedzialkowska,Ewa;Runyan,LucasA;Kudryashova,Elena;Egelman,EdwardH;Kudryashov,DmitriS
沙门氏菌进入宿主肠上皮细胞依赖于其致病岛1效应分子SIPA。我们发现SIPA以亚纳摩尔亲和力以1：2的化学计量比与F-肌动蛋白结合。冷冻-EM重建显示，SipA的球状核心结合在肌动蛋白链之间的凹槽处，而延伸的C-末端臂深入链间隙，从内部稳定F-肌动蛋白。SIPA的异常强大的结合是通过核心的快速结合和手臂指示的非常缓慢的解离的组合实现的。与PI、BeF3和鬼臼蛋白类似，SIPA通过肌动蛋白解聚因子(ADF)/cofilin有效地抑制了肌动蛋白的解聚，这与微丝硬度的增加有关，支持了F-肌动蛋白的机械性质有助于蛋白质伙伴识别其核苷酸状态的假说。与F-肌动蛋白极强的结合使毒素在注射部位的效果最大化，同时将对细胞骨架的整体影响降至最低，并防止宿主细胞检测病原体。
Entry ofSalmonellainto host enterocytes relies on its pathogenicity island 1 effector SipA. We found that SipA binds to F-actin in a 1:2 stoichiometry with sub-nanomolar affinity. A cryo-EM reconstruction revealed that SipA's globular core binds at the groove between actin strands, whereas the extended C-terminal arm penetrates deeply into the inter-strand space, stabilizing F-actin from within. The unusually strong binding of SipA is achieved by a combination of fast association via the core and very slow dissociation dictated by the arm. Similar to Pi, BeF3, and phalloidin, SipA potently inhibited actin depolymerization by actin depolymerizing factor (ADF)/cofilin, which correlated with increased filament stiffness, supporting the hypothesis that F-actin's mechanical properties contribute to the recognition of its nucleotide state by protein partners. The remarkably strong binding to F-actin maximizes the toxin's effects at the injection site while minimizing global influence on the cytoskeleton and preventing pathogen detection by the host cell.