The actin and Rho‐modifying toxins PTC3 and PTC5 of Photorhabdus luminescens: enzyme characterization and induction of MAL/SRF‐dependent transcription
The actin and Rho‐modifying toxins PTC3 and PTC5 of Photorhabdus luminescens: enzyme characterization and induction of MAL/SRF‐dependent transcription
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Photorhabdus luminescens 的肌动蛋白和 Rhoâ 修饰毒素 PTC3 和 PTC5：酶表征和 MAL/SRFâ 依赖性转录的诱导
DOI：
10.1111/cmi.12386
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发表时间：
2015
影响因子：
3.4
通讯作者：
K. Aktories
中科院分区：
文献类型：
--
作者：
Pfaumann;A.E. Lang;C. Schwan;G. Schmidt;K. Aktories
PTC3和PTC5是发光杆菌毒素的三组分，分别由结合组分TcdA1、接头组分TcdB2和酶组分TccC3和TccC5组成。PTC5二磷酸腺苷(ADP)核糖基化Rho蛋白的Gln61/63位导致GTP酶的结构性激活，PTC3ADP核糖基化Thr148处的肌动蛋白从而诱导肌动蛋白聚合。在此，我们鉴定了与TccC3和TccC5的ADP-核糖基转移酶活性有关的氨基酸，并分析了Rho激活TccC5的底物特异性。我们比较了PTC5激活HeLa细胞中Rho蛋白的时间依赖性和大肠杆菌毒素坏死性因子1的作用，后者通过Gln61/63的脱酰胺激活Rho GTP酶。利用荧光素酶报告实验，我们发现PTC5和PTC3通过肌钙蛋白相关的转录因子A(也称为MAL)和AP1刺激基因转录。PTC5对MAL的激活涉及Rho激酶和福尔马林。PTC5激活AP1的途径有两条，分别涉及细胞外信号调节激酶和Jun激酶。
PTC3 and PTC5 are tripartite Tc (toxin complex) toxins fromPhotorhabdus luminescens, which consist of the binding component TcdA1, the linker component TcdB2 and the enzyme components TccC3 and TccC5 respectively. While PTC5 adenosine diphosphate (ADP)‐ribosylates Rho proteins at Gln61/63 resulting in constitutive activation of the GTPases, PTC3 ADP‐ribosylates actin at Thr148 thereby inducing actin polymerization. Here, we identified amino acids involved in ADP‐ribosyltransferase activity of TccC3 and TccC5 and analysed the substrate specificity of Rho‐activating TccC5. We compared the time dependency of Rho protein activation by PTC5 in HeLa cells with the effects ofEscherichia colicytotoxic necrotizing factor 1, which activates Rho GTPases by deamidation of Gln61/63. Using a luciferase reporter assay, we show that PTC5 and PTC3 stimulated gene transcription via myocardin‐related transcription factor A (also called MAL) and AP1. MAL activation by PTC5 involved Rho kinase and formins. Activation of AP1 by PTC5 occurred via two MAP kinase pathways involving extracellular signal‐regulated kinase and Jun kinase respectively.