文章基本信息

标题：Insulin receptor tyrosine kinase substrate links the E. coli O157:H7 actin assembly effectors Tir and EspFU during pedestal formation
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作者：Didier Vingadassalom ; Arunas Kazlauskas ; Brian Skehan 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2009
卷号：106
期号：16
页码：6754-6759
DOI：10.1073/pnas.0809131106
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Enterohemorrhagic Escherichia coli O157:H7 translocates 2 effectors to trigger localized actin assembly in mammalian cells, resulting in filamentous actin "pedestals." One effector, the translocated intimin receptor (Tir), is localized in the plasma membrane and clustered upon binding the bacterial outer membrane protein intimin. The second, the proline-rich effector EspFU (aka TccP) activates the actin nucleation-promoting factor WASP/N-WASP, and is recruited to sites of bacterial attachment by a mechanism dependent on an Asn-Pro-Tyr (NPY458) sequence in the Tir C-terminal cytoplasmic domain. Tir, EspFU, and N-WASP form a complex, but neither EspFU nor N-WASP bind Tir directly, suggesting involvement of another protein in complex formation. Screening of the mammalian SH3 proteome for the ability to bind EspFU identified the SH3 domain of insulin receptor tyrosine kinase substrate (IRTKS), a factor known to regulate the cytoskeleton. Derivatives of WASP, EspFU, and the IRTKS SH3 domain were capable of forming a ternary complex in vitro, and replacement of the C terminus of Tir with the IRTKS SH3 domain resulted in a fusion protein competent for actin assembly in vivo. A second domain of IRTKS, the IRSp53/MIM homology domain (IMD), bound to Tir in a manner dependent on the C-terminal NPY458 sequence, thereby recruiting IRTKS to sites of bacterial attachment. Ectopic expression of either the IRTKS SH3 domain or the IMD, or genetic depletion of IRTKS, blocked pedestal formation. Thus, enterohemorrhagic E. coli translocates 2 effectors that bind to distinct domains of a common host factor to promote the formation of a complex that triggers robust actin assembly at the plasma membrane.
关键词：enterohemorrhagic Escherichia coli ; IRSp53/MIM homology domain ; IRTKS ; N-WASP ; SH3 domain