Molecular basis of evasion of Legionella from xenophagy

2015 Fiscal Year Final Research Report

• Project/Area Number: 26670212
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Bacteriology (including mycology)
• Research Institution: Osaka University
• Principal Investigator: NAGAI Hiroki 大阪大学, 微生物病研究所, 准教授 (80222173)
• Co-Investigator(Renkei-kenkyūsha): KUBORI Tomoko 大阪大学, 微生物病研究所, 特任講師 (20397657)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 細菌 / オートファジー / レジオネラ

Outline of Final Research Achievements

Bacterial pathogens establish intracellular niches known as bacteria-containing vacuoles in which they can survive and replicate. Ubiquitin-dependent selective autophagy (xenophagy) is a host defense mechanism to counteract infection with bacteria. The Legionella effector protein RavZ interferes with autophagy by irreversibly deconjugating LC3, an autophagy-related ubiquitin-like protein, from phosphatidylethanolamine. Here we show that, using a co-infection system with Salmonella and Legionella, RavZ exhibited the activity to interfere ubiquitin recruitment to the Salmonella-containing vacuoles. Using semi-permeabilized cells and purified RavZ, ubiquitin on the vacuoles was removed depending on the catalytic cysteine residue of RavZ for LC3 deconjugation. These raise the possibility that the targets of the cysteine protease RavZ include not only LC3 but also ubiquitin. Ubiquitin targeting by RavZ is thought to be a strategy of Legionella to evade host xenophagy.

Free Research Field

細菌学、分子生物学