AUTHOR=Qiu Jiazhang , Luo Zhao-Qing 

TITLE=Hijacking of the Host Ubiquitin Network by Legionella pneumophila

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=7

YEAR=2017

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2017.00487

DOI=10.3389/fcimb.2017.00487

ISSN=2235-2988

ABSTRACT=<p>Protein ubiquitination is critical for regulation of numerous eukaryotic cellular processes such as protein homeostasis, cell cycle progression, immune response, DNA repair, and vesicular trafficking. Ubiquitination often leads to the alteration of protein stability, subcellular localization, or interaction with other proteins. Given the importance of ubiquitination in the regulation of host immunity, it is not surprising that many infectious agents have evolved strategies to interfere with the ubiquitination network with sophisticated mechanisms such as functional mimicry. The facultative intracellular pathogen <italic>Legionella pneumophila</italic> is the causative agent of Legionnaires' disease. <italic>L. pneumophila</italic> is phagocytosed by macrophages and is able to replicate within a niche called <underline>L</underline>egionella-<underline>c</underline>ontaining <underline>v</underline>acuole (LCV). The biogenesis of LCV is dependent upon the Dot/Icm type IV secretion system which delivers more than 330 effector proteins into host cytosol. The optimal intracellular replication of <italic>L. pneumophila</italic> requires the host ubiquitin-proteasome system. Furthermore, membranes of the bacterial phagosome are enriched with ubiquitinated proteins in a way that requires its Dot/Icm type IV secretion system, suggesting the involvement of effectors in the manipulation of the host ubiquitination machinery. Here we summarize recent advances in our understanding of mechanisms exploited by <italic>L. pneumophila</italic> effector proteins to hijack the host ubiquitination pathway.</p>