Molecular architecture, polar targeting and biogenesis of the Legionella Dot/Icm T4SS
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 microscop...
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Published in | Nature microbiology Vol. 4; no. 7; pp. 1173 - 1182 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
London
Nature Publishing Group UK
01.07.2019
Nature Publishing Group |
Subjects | |
Online Access | Get full text |
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Summary: | 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.
A combination of electron cryotomography and immunofluorescence microscopy reveals the structure of the core transmembrane subcomplex of the
Legionella
defective in organelle trafficking (Dot)/intracellular multiplication (Icm) type IVB secretion system (T4BSS) and an early-stage assembly process by which T4BSS components are targeted to the bacterial poles by DotU and IcmF. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 Contributions: D.G., K.C.J., J.P.V., and G.J.J. conceived the project. K.C.J., J.P.V and J.G constructed and characterized the L. pneumophila expression plasmids and strains. K.C.J. and J.P.V collected IF data. D.G. collected tomography data. D.G., K.C.J., J.P.V., G.J.J, Y.W.C., and L.T. analyzed data. A.G. made the supplementary movie 1. D.G., J.P.V., K.C.J., and G.J.J. wrote the manuscript with input from other authors. Lead contact: jensen@caltech.edu These authors contributed equally Current Address: Departments of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. |
ISSN: | 2058-5276 2058-5276 |
DOI: | 10.1038/s41564-019-0427-4 |