The Arf GTPase-activating protein family is exploited by Salmonella enterica serovar Typhimurium to invade nonphagocytic host cells.
The Arf GTPase-activating protein family is exploited by Salmonella enterica serovar Typhimurium to invade nonphagocytic host cells.
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DOI：
10.1128/mbio.02253-14
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发表时间：
2015-02-10
期刊：
影响因子：
6.4
通讯作者：
Koronakis V
中科院分区：
文献类型：
--
作者：
Davidson AC;Humphreys D;Brooks AB;Hume PJ;Koronakis V
为了建立细胞内感染，沙门氏菌通过破坏细胞 Arf 鸟嘌呤核苷酸交换因子 (GEF) 来触发宿主细胞膜波动和入侵，GEF 通过促进 GTP 结合来激活 Arf1 和 Arf6 GTP 酶。细胞 Arf GTP 酶激活蛋白 (GAP) 家族可以通过刺激 GTP 水解来下调 Arf 信号传导，但它们是否在感染过程中发挥作用尚不清楚。在这里，我们发现了不同的 Arf GAP 家族成员在沙门氏菌入侵中的显着作用。 Arf6 GAP ACAP1 和 ADAP1 以及 Arf1 GAP ASAP1 定位于沙门氏菌诱导的褶边，而质膜定位的 Arf6 GAP ARAP3 和 GIT1 或高尔基体相关的 Arf1 GAP1 则不是这种情况。令人惊讶的是，我们发现 ACAP1、ADAP1 或 ASAP1 的缺失会损害沙门氏菌的侵袭，这表明 GAP 不能仅仅被视为细胞骨架重塑的终结者。通过表达快速循环的 Arf 衍生物，沙门氏菌入侵在 Arf GAP 耗尽的细胞中恢复，表明 Arf GTP/GDP 循环促进沙门氏菌入侵。与这一观点一致，不能经历 GTP/GDP 循环的组成型活性和显性失活 Arf 衍生物均抑制入侵。此外，我们证明 Arf GEF 和 GAP 在入侵沙门氏菌中共定位，并协同驱动 Arf1 依赖性病原体入侵。这项研究表明，沙门氏菌利用 Arf GEF 和 GAP 之间显着的相互作用来指导 Arf GTP 酶激活和失活的循环。这些循环驱动沙门氏菌细胞骨架重塑并实现细胞内感染。为了引发感染，沙门氏菌细菌病原体会重塑哺乳动物肌动蛋白细胞骨架，并通过破坏激活 Arf1 和 Arf6 GTP 酶的宿主 Arf GEF 来侵入宿主细胞。细胞 Arf GAP 使 Arf GTP 酶失活并负向调节细胞过程，但它们在感染过程中是否靶向 Arf 尚不清楚。在这里，我们发现了 Arf GAP 家族在沙门氏菌入侵中的重要作用。令人惊讶的是，我们发现 Arf1 和 Arf6 GAP 与其 Arf GEF 对应物合作，促进 Arf GTP 酶激活和失活的循环，从而指导病原体入侵。该报告表明，GAP 蛋白促进肌动蛋白依赖性过程，并且不一定限于负向调节细胞信号传导。它揭示了 Arf GEF 和 GAP 之间显着的相互作用，沙门氏菌利用这种相互作用来建立感染，并扩展了我们对 Arf GTP 酶调节的细胞骨架重塑的理解。
To establish intracellular infections, Salmonella bacteria trigger host cell membrane ruffling and invasion by subverting cellular Arf guanine nucleotide exchange factors (GEFs) that activate Arf1 and Arf6 GTPases by promoting GTP binding. A family of cellular Arf GTPase-activating proteins (GAPs) can downregulate Arf signaling by stimulating GTP hydrolysis, but whether they do this during infection is unknown. Here, we uncovered a remarkable role for distinct Arf GAP family members in Salmonella invasion. The Arf6 GAPs ACAP1 and ADAP1 and the Arf1 GAP ASAP1 localized at Salmonella-induced ruffles, which was not the case for the plasma membrane-localized Arf6 GAPs ARAP3 and GIT1 or the Golgi-associated Arf1 GAP1. Surprisingly, we found that loss of ACAP1, ADAP1, or ASAP1 impaired Salmonella invasion, revealing that GAPs cannot be considered mere terminators of cytoskeleton remodeling. Salmonella invasion was restored in Arf GAP-depleted cells by expressing fast-cycling Arf derivatives, demonstrating that Arf GTP/GDP cycles facilitate Salmonella invasion. Consistent with this view, both constitutively active and dominant-negative Arf derivatives that cannot undergo GTP/GDP cycles inhibited invasion. Furthermore, we demonstrated that Arf GEFs and GAPs colocalize at invading Salmonella and collaborate to drive Arf1-dependent pathogen invasion. This study revealed that Salmonella bacteria exploit a remarkable interplay between Arf GEFs and GAPs to direct cycles of Arf GTPase activation and inactivation. These cycles drive Salmonella cytoskeleton remodeling and enable intracellular infections. To initiate infections, the Salmonella bacterial pathogen remodels the mammalian actin cytoskeleton and invades host cells by subverting host Arf GEFs that activate Arf1 and Arf6 GTPases. Cellular Arf GAPs deactivate Arf GTPases and negatively regulate cell processes, but whether they target Arfs during infection is unknown. Here, we uncovered an important role for the Arf GAP family in Salmonella invasion. Surprisingly, we found that Arf1 and Arf6 GAPs cooperate with their Arf GEF counterparts to facilitate cycles of Arf GTPase activation and inactivation, which direct pathogen invasion. This report illustrates that GAP proteins promote actin-dependent processes and are not necessarily restricted to negatively regulating cellular signaling. It uncovers a remarkable interplay between Arf GEFs and GAPs that is exploited by Salmonella to establish infection and expands our understanding of Arf GTPase-regulated cytoskeleton remodeling.