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Abstract Legionella pneumophilautilizes the Dot/Icm type IVB secretion system to deliver hundreds of effector proteins inside eukaryotic cells to ensure intracellular replication. Our understanding of the molecular functions of the largest pathogenic arsenal known to the bacterial world remains incomplete. By leveraging advancements in 3D protein structure prediction, we provide a comprehensive structural analysis of 368 L. pneumophilaeffectors, representing a global atlas of predicted functional domains summarized in a database (https://pathogens3d.org/legionella-pneumophila). Our analysis identified 157 types of diverse functional domains in 287 effectors, including 159 effectors with no prior functional annotations. Furthermore, we identified 35 cryptic domains in 30 effector models that have no similarity with experimentally structurally characterized proteins, thus, hinting at novel functionalities. Using this analysis, we demonstrate the activity of thirteen functional domains, including three cryptic domains, predicted inL. pneumophilaeffectors to cause growth defects in theSaccharomyces cerevisiaemodel system. This illustrates an emerging strategy of exploring synergies between predictions and targeted experimental approaches in elucidating novel effector activities involved in infection.
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Legionella pneumophila targets autophagosomes and promotes host autophagy during late infection
Abstract Autophagy is a fundamental eukaryotic process that mediates clearance of unwanted molecules and facilitates nutrient release. The bacterial pathogenLegionella pneumophilaestablishes an intracellular niche within phagocytes by manipulating host cellular processes, such as autophagy. Effector proteins translocated byL. pneumophila’s Dot/Icm type IV secretion system have been shown to suppress autophagy. However evidence suggests that overall inhibition of autophagy may be detrimental to the bacterium. As autophagy contributes to cellular homeostasis and nutrient acquisition,L. pneumophilamay translocate effectors that promote autophagy for these benefits. Here, we show that effector protein Lpg2411 binds phosphatidylinositol-3-phosphate lipids and preferentially binds autophagosomes. Translocated Lpg2411 accumulates late during infection and co-localizes with the autophagy receptor p62 and ubiquitin. Furthermore, autophagy is inhibited to a greater extent in host cells infected with a mutant strain lacking Lpg2411 compared to those infected with wild-typeL. pneumophila,indicating that Lpg2411 stimulates autophagy to support the bacterium’s intracellular lifestyle. SummaryLegionella pneumophilatranslocates several effector proteins that inhibit autophagic processes. In this study, we find that the effector protein Lpg2411 targets autophagosomes during late stages of infection and promotes autophagy.
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- Award ID(s):
- 1750742
- PAR ID:
- 10557076
- Publisher / Repository:
- bioRxiv
- Date Published:
- Format(s):
- Medium: X
- Institution:
- bioRxiv
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Posted Content:
- https://doi.org/10.1101/2021.07.08.451723
