scholarly journals Agrobacterium-Mediated T-DNA Transfer and Integration by Minimal VirD2 Consisting of the Relaxase Domain and a Type IV Secretion System Translocation Signal

2009 ◽  
Vol 22 (11) ◽  
pp. 1356-1365 ◽  
Author(s):  
Maartje van Kregten ◽  
Beatrice I. Lindhout ◽  
Paul J. J. Hooykaas ◽  
Bert J. van der Zaal
Keyword(s):  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Terminal Part ◽  
Type Iv ◽  
C Terminus ◽  
Localization Signal ◽  
Translocation Domain ◽  
First Time

The VirD2 protein of Agrobacterium tumefaciens is essential for processing and transport of the T-DNA. It has at least three functional domains: a relaxase domain at the N terminus, a bipartite nuclear localization signal (NLS), and a sequence called ω at the C terminus. We confirm here that deletions of the C-terminal part of VirD2 led to lack of transfer of T-DNA but, for the first time, we report that virulence is restored when these truncations are supplemented at the C terminus by a short translocation signal from the VirF protein. The lack of virulence of C-terminal deletions suggests that the C-terminal part contains all or part of the translocation signal of VirD2. Using a novel series of mutant VirD2 proteins, the C-terminal half of VirD2 was further investigated. We demonstrate that the C-terminal 40 amino acids of VirD2, which include the NLS and ω, contain all or part of the translocation domain necessary for transport of VirD2 into plant cells, while another element is present in the middle of the protein. The finding that a type IV secretion system transport signal at the C terminus of VirD2 is necessary for virulence provides evidence for the role of VirD2 as a pilot protein driving translocation of the T-strand.

scholarly journals Critical Role of ASC Inflammasomes and Bacterial Type IV Secretion System in Caspase-1 Activation and Host Innate Resistance toBrucella abortusInfection

2013 ◽  
Vol 190 (7) ◽  
pp. 3629-3638 ◽  
Author(s):  
Marco Tulio R. Gomes ◽  
Priscila C. Campos ◽  
Fernanda S. Oliveira ◽  
Patricia P. Corsetti ◽  
Karina R. Bortoluci ◽  
...  
Keyword(s):  
Critical Role ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Innate Resistance ◽  
Caspase 1 ◽  
Type Iv ◽  
Bacterial Type

scholarly journals Four VirB6 Paralogs and VirB9 Are Expressed and Interact in Ehrlichia chaffeensis-Containing Vacuoles

2008 ◽  
Vol 191 (1) ◽  
pp. 278-286 ◽  
Author(s):  
Weichao Bao ◽  
Yumi Kumagai ◽  
Hua Niu ◽  
Mamoru Yamaguchi ◽  
Koshiro Miura ◽  
...  
Keyword(s):  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Human Leukemia ◽  
Ehrlichia Chaffeensis ◽  
Tick Cell ◽  
Type Iv ◽  
Important Virulence Factor ◽  
Human Monocytic Ehrlichiosis ◽  
First Time

ABSTRACT The type IV secretion system is an important virulence factor in several host cell-associated pathogens, as it delivers various bacterial macromolecules to target eukaryotic cells. Genes homologous to several virB genes and virD4 of Agrobacterium tumefaciens are found in an intravacuolar pathogen Ehrlichia chaffeensis, the tick-borne causative agent of human monocytic ehrlichiosis. In particular, despite its small genome size, E. chaffeensis has four tandem virB6 paralogs (virB6-1, -2, -3, and -4) that are 3- to 10-fold larger than A. tumefaciens virB6. The present study for the first time illustrates the relevance of the larger quadruple VirB6 paralogs by demonstrating the protein expression and interaction in E. chaffeensis. All four virB6 paralogs were cotranscribed in THP-1 human leukemia and ISE6 tick cell cultures. The four VirB6 proteins and VirB9 were expressed by E. chaffeensis in THP-1 cells, and amounts of these five proteins were similar in isolated E. chaffeensis-containing vacuoles and vacuole-free E. chaffeensis. In addition, an 80-kDa fragment of VirB6-2 was detected, which was strikingly more prevalent in E. chaffeensis-containing vacuoles than in vacuole-free E. chaffeensis. Coimmunoprecipitation analysis revealed VirB9 interaction with VirB6-1 and VirB6-2; VirB6-4 interaction with VirB6-1, VirB6-2, and VirB6-3; and VirB6-2 80-kDa fragment interaction with VirB6-3 and VirB6-4. The interaction of VirB9 and VirB6-2 was confirmed by far-Western blotting. The results suggest that E. chaffeensis VirB9, the quadruple VirB6 proteins, and the VirB6-2 80-kDa fragment form a unique molecular subassembly to cooperate in type IV secretion.

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.

Role of Cal, the colicin A lysis protein, in two steps of colicin A release and in the interaction with colicin A–porin complexes

Microbiology ◽  
2004 ◽  
Vol 150 (11) ◽  
pp. 3867-3875 ◽  
Author(s):  
Danièle Cavard
Keyword(s):  
Escherichia Coli ◽  
Insoluble Fraction ◽  
Cysteine Residue ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Temperature Sensitive ◽  
Type Iv ◽  
Definition Of

Release of colicin A was studied in Escherichia coli cells that differed in expressing the colicin A lysis protein (Cal). Pools of released and unreleased colicin A were harvested throughout colicin A induction. The amount of colicin A in each pool varied with the time of induction, allowing the definition of two sequential steps in colicin A release, one of which was dependent on Cal. Each step of colicin A release was differently affected in cells containing Cal mutants in which the N-terminal cysteine residue was substituted by either proline or threonine, preventing them from being acylated and matured. These Cal mutants were only observed in degP cells, indicating that the DegP protease cleaved the unacylated precursor of Cal. Cal was found in the insoluble fraction of the pools of released and unreleased colicin A together with the hetero-oligomers of colicin A and porins (colicins Au). The biogenesis of colicins Au was studied in temperature-sensitive secA and secY strains and found to be Sec-independent, indicating that they are formed by newly synthesized colicin A binding to mature porins already incorporated in the outer membrane. Cal is a lipoprotein similar to VirB7, a constituent of the type IV secretion system. It would interact with colicins Au to constitute the colicin A export machinery.

scholarly journals Reassessing the Role of DotF in the Legionella pneumophila Type IV Secretion System

PLoS ONE ◽  
2013 ◽  
Vol 8 (6) ◽  
pp. e65529 ◽  
Author(s):  
Molly C. Sutherland ◽  
Kelsey A. Binder ◽  
Phillip Y. Cualing ◽  
Joseph P. Vogel
Keyword(s):  
Legionella Pneumophila ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv

scholarly journals Implication of the Type IV Secretion System in the Pathogenicity of Vibrio tapetis, the Etiological Agent of Brown Ring Disease Affecting the Manila Clam Ruditapes philippinarum

2021 ◽  
Vol 11 ◽  
Author(s):  
Alexandra Rahmani ◽  
François Delavat ◽  
Christophe Lambert ◽  
Nelly Le Goic ◽  
Eric Dabas ◽  
...  
Keyword(s):  
Ruditapes Philippinarum ◽  
Secretion System ◽  
Infection Process ◽  
Type Iv Secretion ◽  
Manila Clam ◽  
Type Iv Secretion System ◽  
Type Iv ◽  
T4ss Gene ◽  
Brown Ring Disease

Vibrio tapetis is a Gram-negative bacterium that causes infections of mollusk bivalves and fish. The Brown Ring Disease (BRD) is an infection caused by V. tapetis that primarily affects the Manila clam Ruditapes philippinarum. Recent studies have shown that a type IV secretion system (T4SS) gene cluster is exclusively found in strains of V. tapetis pathogenic to clams. However, whether the T4SS is implicated or not during the infection process remains unknown. The aim of this study was to create and characterize a V. tapetis T4SS null mutant, obtained by a near-complete deletion of the virB4 gene, in order to determine the role of T4SS in the development of BRD. This study demonstrated that the T4SS is neither responsible for the loss of hemocyte adhesion capacities, nor for the decrease of the lysosomal activity during BRD. Nevertheless, we observed a 50% decrease of the BRD prevalence and a decrease of mortality dynamics with the ΔvirB4 mutant. This work demonstrates that the T4SS of V. tapetis plays an important role in the development of BRD in the Manila clam.

scholarly journals Stabilization of the Pertussis Toxin Secretion Apparatus by the C Terminus of PtlD

2008 ◽  
Vol 190 (21) ◽  
pp. 7285-7290 ◽  
Author(s):  
Anita Verma ◽  
Anissa M. Cheung ◽  
Drusilla L. Burns
Keyword(s):  
Amino Acids ◽  
Pertussis Toxin ◽  
Bordetella Pertussis ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Type Iv ◽  
C Terminus ◽  
Toxin Secretion ◽  
The Stability

ABSTRACT Pertussis toxin (PT) is secreted from Bordetella pertussis by a type IV secretion system, known as the Ptl transporter, that comprises nine different proteins, PtlA to PtlI. In this study, we found that PtlD is required for the stability of three Ptl proteins, PtlE, PtlF, and PtlH. A region limited to the C-terminal 72 amino acids of PtlD (amino acids 392 to 463) was sufficient for maintaining the stability of PtlE, PtlF, and PtlH, although this region was not sufficient to support secretion of the toxin. Further analysis demonstrated that a stretch of 10 amino acids at the C-terminal end of PtlD (amino acids 425 to 434) contributes to transporter stability.

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