the ehec type iii effector nlel is an e3 ubiquitin ligase that modulates pedestal formation肠出血性大肠杆菌感染类型iii效应nlel是一个调节底座的e3泛素连接酶的形成.pdf

The EHEC Type III Effector NleL Is an E3 Ubiquitin Ligase That Modulates Pedestal Formation 1 1 2¤ 2 Heather Piscatelli , Shalaka A. Kotkar , Megan E. McBee , Sureshkumar Muthupalani , David B. 2 3 4 1 Schauer , Robert E. Mandrell , John M. Leong , Daoguo Zhou * 1 Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America, 2 Department of Biological Engineering and Comparative Medicine, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America, 3 Agricultural Research Service, United States Department of Agriculture, Albany, California, United States of America, 4 Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America Abstract Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes hemorrhagic colitis and may result in potentially fatal hemolytic uremia syndrome in humans. EHEC colonize the intestinal mucosa and promote the formation of actin-rich pedestals via translocated type III effectors. Two EHEC type III secreted effectors, Tir and EspFu/TccP, are key players for pedestal formation. We discovered that an EHEC effector protein called Non-LEE-encoded Ligase (NleL) is an E3 ubiquitin ligase. In vitro, we showed that the NleL C753 residue is critical for its E3 ligase activity. Functionally, we demonstrated that NleL E3 ubiquitin ligase activity is involved in modulating Tir-mediated pedestal formation. Surprisingly, EHEC mutant strain deficient in the E3 ligase activity induced more