scholarly journals The crystal structure of LidA, a translocated substrate of the Legionella pneumophila type IV secretion system

2013 ◽  
Vol 4 (12) ◽  
pp. 897-900 ◽  
Author(s):  
Geng Meng ◽  
Xiaojing An ◽  
Sheng Ye ◽  
Yong Liu ◽  
Wenzhuang Zhu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Legionella Pneumophila ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv

Crystal structure of Legionella pneumophila type IV secretion system effector LegAS4

2015 ◽  
Vol 465 (4) ◽  
pp. 817-824 ◽  
Author(s):  
Jonghyeon Son ◽  
Chang Hwa Jo ◽  
Ravichandran N. Murugan ◽  
Jeong Kyu Bang ◽  
Kwang Yeon Hwang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Legionella Pneumophila ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv

scholarly journals IcmF and DotU Are Required for Optimal Effector Translocation and Trafficking of the Legionella pneumophila Vacuole

2004 ◽  
Vol 72 (10) ◽  
pp. 5972-5982 ◽  
Author(s):  
Susan M. VanRheenen ◽  
Guillaume Duménil ◽  
Ralph R. Isberg
Keyword(s):  
Legionella Pneumophila ◽  
Severe Form ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Intracellular Growth ◽  
Macrophage Infection ◽  
Type Iv ◽  
Bacterial Mutants ◽  
Bacterial Replication

ABSTRACT The gram-negative bacterium Legionella pneumophila causes a severe form of pneumonia called Legionnaires' disease, characterized by bacterial replication within alveolar macrophages. Prior to intracellular replication, the vacuole harboring the bacterium must first escape trafficking to the host lysosome, a process that is dependent on the Dot/Icm type IV secretion system. To identify genes required for intracellular growth, bacterial mutants were isolated that were delayed in escape from the macrophage but which retain a minimally functional Dot/Icm machinery. The mutations were found in eight distinct genes, including three genes known to be required for optimal intracellular growth. Two of these genes, icmF and dotU, are located at one end of a cluster of genes that encode the type IV secretion system, yet both icmF and dotU lack orthologs in other type IV translocons. DotU protein is degraded in the early postexponential phase in wild-type L. pneumophila and at all growth phases in an icmF mutant. IcmF contains an extracytoplasmic domain(s) based on accessibility to a membrane-impermeant amine-reactive reagent. In the absence of either gene, L. pneumophila targets inappropriately to LAMP-1-positive compartments during macrophage infection, is defective in the formation of replicative vacuoles, and is impaired in the translocation of the effector protein SidC. Therefore, although IcmF and DotU do not appear to be part of the core type IV secretion system, these proteins are necessary for an efficiently functioning secretion apparatus.

scholarly journals Polar targeting and assembly of theLegionellaDot/Icm type IV secretion system (T4SS) by T6SS-related components

2018 ◽  
Author(s):  
KwangCheol C. Jeong ◽  
Jacob Gyore ◽  
Lin Teng ◽  
Debnath Ghosal ◽  
Grant J. Jensen ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Type Iv Secretion System ◽  
Membrane Complex ◽  
Type Iv ◽  
Legionnaires Disease ◽  
Type Ivb Secretion ◽  
Type Ivb Secretion System

SummaryLegionella pneumophila, the causative agent of Legionnaires’ disease, survives and replicates inside amoebae and macrophages by injecting a large number of protein effectors into the host cells’ cytoplasm via the Dot/Icm type IVB secretion system (T4BSS). Previously, we showed that the Dot/Icm T4BSS is localized to both poles of the bacterium and that polar secretion is necessary for the proper targeting of theLegionellacontaining vacuole (LCV). Here we show that polar targeting of the Dot/Icm core-transmembrane subcomplex (DotC, DotD, DotF, DotG and DotH) is mediated by two Dot/Icm proteins, DotU and IcmF, which are able to localize to the poles ofL. pneumophilaby themselves. Interestingly, DotU and IcmF are homologs of the T6SS components TssL and TssM, which are part of the T6SS membrane complex (MC). We propose thatLegionellaco-opted these T6SS components to a novel function that mediates subcellular localization and assembly of this T4SS. Finally, in depth examination of the biogenesis pathway revealed that polar targeting and assembly of theLegionellaT4BSS apparatus is mediated by an innovative “outside-inside” mechanism.

scholarly journals The Dot/Icm Type IV Secretion System of Legionella pneumophila Is Essential for the Induction of Apoptosis in Human Macrophages

2002 ◽  
Vol 70 (3) ◽  
pp. 1657-1663 ◽  
Author(s):  
Steven D. Zink ◽  
Lisa Pedersen ◽  
Nicholas P. Cianciotto ◽  
Yousef Abu Kwaik
Keyword(s):  
Legionella Pneumophila ◽  
Mammalian Cells ◽  
Bacterial Pathogen ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Ii Secretion ◽  
Type Iv ◽  
Induction Of Apoptosis

ABSTRACT We have previously shown that Legionella pneumophila induces caspase 3-dependent apoptosis in mammalian cells during early stages of infection. In this report, we show that nine L. pneumophila strains with mutations in the dotA, dotDCB, icmT, icmGCD, and icmJB loci are completely defective in the induction of apoptosis, in addition to their severe defects in intracellular replication and pore formation-mediated cytotoxicity. Importantly, all nine dot/icm mutants were complemented for all their defective phenotypes with the respective wild-type loci. We show that the role of the Dot/Icm type IV secretion system in the induction of apoptosis is independent of the RtxA toxin, the dot/icm-regulated pore-forming toxin, and the type II secretion system. However, the pore-forming toxin, which is triggered upon entry into the postexponential growth phase, enhances the ability of L. pneumophila to induce apoptosis. Our data provide the first example of the role of a type IV secretion system of a bacterial pathogen in the induction of apoptosis in the host cell.

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