Molecular architecture, polar targeting and biogenesis of the Legionella Dot/Icm T4SS

Debnath Ghosal, Kwangcheol C. Jeong, Yi Wei Chang, Jacob Gyore, Lin Teng, Adam Gardner, Joseph P. Vogel, Grant J. Jensen

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

Legionella pneumophila survives and replicates inside host cells by secreting ~300 effectors through the defective in organelle trafficking (Dot)/intracellular multiplication (Icm) type IVB secretion system (T4BSS). Here, we used complementary electron cryotomography and immunofluorescence microscopy to investigate the molecular architecture and biogenesis of the Dot/Icm secretion apparatus. Electron cryotomography mapped the location of the core and accessory components of the Legionella core transmembrane subcomplex, revealing a well-ordered central channel that opens into a large, windowed secretion chamber with an unusual 13-fold symmetry. Immunofluorescence microscopy deciphered an early-stage assembly process that begins with the targeting of Dot/Icm components to the bacterial poles. Polar targeting of this T4BSS is mediated by two Dot/Icm proteins, DotU and IcmF, that, interestingly, are homologues of the T6SS membrane complex components TssL and TssM, suggesting that the Dot/Icm T4BSS is a hybrid system. Together, these results revealed that the Dot/Icm complex assembles in an ‘axial-to-peripheral’ pattern.

Original languageEnglish
Pages (from-to)1173-1182
Number of pages10
JournalNature microbiology
Volume4
Issue number7
DOIs
StatePublished - Jul 1 2019

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