Volume 77, Issue 12 pp. 1535-1542
research papers

Legionella effector LegA15/AnkH contains an unrecognized cysteine protease-like domain and displays structural similarity to LegA3/AnkD, but differs in host cell localization

Ivy Yeuk Wah Chung

Ivy Yeuk Wah Chung

University of Saskatchewan, Department of Biochemistry, Microbiology and Immunology, Saskatoon, Saskatchewan, Canada

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Lei Li

Lei Li

University of Saskatchewan, Department of Biochemistry, Microbiology and Immunology, Saskatoon, Saskatchewan, Canada

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Miroslaw Cygler

Corresponding Author

Miroslaw Cygler

University of Saskatchewan, Department of Biochemistry, Microbiology and Immunology, Saskatoon, Saskatchewan, Canada

Miroslaw Cygler, e-mail: [email protected]Search for more papers by this author
First published: 11 November 2021

Abstract

Legionella pneumophila is a human pathogen that causes Legionnaires' disease, a severe form of pneumonia. It can be found in various aquatic environments ranging from cooling towers to ponds. In addition to causing disease in humans, it can also infect free-living amoebae commonly found in various aquatic environments. Once inside a human lung macrophage, it creates a niche called the Legionella-containing vacuole where it can evade phagolysosomal degradation and replicate. During infection, normal cellular functions are hijacked by proteins that are secreted by the pathogen, called bacterial effectors. Here, the structural characterization of the effector LegA15/AnkD is reported. The protein contains an ankyrin-repeat domain followed by a cysteine protease-like (CPL) domain with a putative catalytic triad consisting of His268–Asn290–Cys361. The CPL domain shows similarity to the CE clan in the MEROPS database, which contains ubiquitin-like hydrolases. The C-terminal segment of LegA15, including the CPL domain, shows structural similarity to another effector, LegA3/AnkH, while they share only 12% sequence identity. When expressed in mammalian cells, LegA15 is localized within the cytoplasm, in contrast to LegA3, which localizes to the nucleus.

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