Legionella hijacks the host Golgi-to-ER retrograde pathway for the association of Legionella-containing vacuole with the ER

PLoS Pathog. 2021 Mar 24;17(3):e1009437. doi: 10.1371/journal.ppat.1009437. eCollection 2021 Mar.

Abstract

Legionella pneumophila (L. pneumophila) is a gram-negative bacterium that replicates in a compartment that resembles the host endoplasmic reticulum (ER). To create its replicative niche, L. pneumophila manipulates host membrane traffic and fusion machineries. Bacterial proteins called Legionella effectors are translocated into the host cytosol and play a crucial role in these processes. In an early stage of infection, Legionella subverts ER-derived vesicles (ERDVs) by manipulating GTPase Rab1 to facilitate remodeling of the Legionella-containing vacuole (LCV). Subsequently, the LCV associates with the ER in a mechanism that remains elusive. In this study, we show that L. pneumophila recruits GTPases Rab33B and Rab6A, which regulate vesicle trafficking from the Golgi to the ER, to the LCV to promote the association of LCV with the ER. We found that recruitment of Rab6A to the LCV depends on Rab33B. Legionella effector SidE family proteins, which phosphoribosyl-ubiquitinate Rab33B, were found to be necessary for the recruitment of Rab33B to the LCV. Immunoprecipitation experiments revealed that L. pneumophila facilitates the interaction of Rab6 with ER-resident SNAREs comprising syntaxin 18, p31, and BNIP1, but not tethering factors including NAG, RINT-1, and ZW10, which are normally required for syntaxin 18-mediated fusion of Golgi-derived vesicles with the ER. Our results identified a Rab33B-Rab6A cascade on the LCV and the interaction of Rab6 with ER-resident SNARE proteins for the association of LCV with the ER and disclosed the unidentified physiological role of SidE family proteins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism
  • Endoplasmic Reticulum / metabolism*
  • Endoplasmic Reticulum / microbiology
  • Golgi Apparatus / metabolism*
  • Golgi Apparatus / microbiology
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Legionella pneumophila / metabolism
  • Legionella pneumophila / pathogenicity*
  • Legionnaires' Disease / metabolism*
  • Protein Transport / physiology
  • Vacuoles / metabolism
  • Vacuoles / microbiology*

Substances

  • Bacterial Proteins

Grants and funding

This work was supported in part by Grant-in-Aid for Scientific Research, #24790425, #26713016, #18H02656 and #20H05772 (to KA) and #25291029 (to MT); the MEXT-Supported Program for the Strategic Research Foundation at Private Universities (to KA and MT) from the Ministry of Education, Culture, Sports, Science and Technology of Japan (URL: https://www.jsps.go.jp/j-grantsinaid/); the Uehara Memorial Foundation (to KA) URL: https://www.ueharazaidan.or.jp/; the Naito Foundation (to KA) URL: https://www.naito-f.or.jp/jp/index.php; Takeda Science Foundation (to KA) URL: https://www.takeda-sci.or.jp/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.