scholarly journals The Dimer Interface of Agrobacterium tumefaciens VirB8 Is Important for Type IV Secretion System Function, Stability, and Association of VirB2 with the Core Complex

2011 ◽  
Vol 193 (9) ◽  
pp. 2097-2106 ◽  
Author(s):  
D. Sivanesan ◽  
C. Baron
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
System Function ◽  
Core Complex ◽  
Dimer Interface ◽  
The Core ◽  
Type Iv

scholarly journals Structural analysis of the Legionella pneumophila Dot/Icm type IV secretion system core complex

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Clarissa L Durie ◽  
Michael J Sheedlo ◽  
Jeong Min Chung ◽  
Brenda G Byrne ◽  
Min Su ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Structural Features ◽  
Secretion System ◽  
Effector Proteins ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Type Iv Secretion System ◽  
Core Complex ◽  
The Core ◽  
Type Iv

Legionella pneumophila is an opportunistic pathogen that causes the potentially fatal pneumonia Legionnaires’ Disease. This infection and subsequent pathology require the Dot/Icm Type IV Secretion System (T4SS) to deliver effector proteins into host cells. Compared to prototypical T4SSs, the Dot/Icm assembly is much larger, containing ~27 different components including a core complex reported to be composed of five proteins: DotC, DotD, DotF, DotG, and DotH. Using single particle cryo-electron microscopy (cryo-EM), we report reconstructions of the core complex of the Dot/Icm T4SS that includes a symmetry mismatch between distinct structural features of the outer membrane cap (OMC) and periplasmic ring (PR). We present models of known core complex proteins, DotC, DotD, and DotH, and two structurally similar proteins within the core complex, DotK and Lpg0657. This analysis reveals the stoichiometry and contact interfaces between the key proteins of the Dot/Icm T4SS core complex and provides a framework for understanding a complex molecular machine.

scholarly journals Structure of the VirB4 ATPase, alone and bound to the core complex of a type IV secretion system

2012 ◽  
Vol 109 (28) ◽  
pp. 11348-11353 ◽  
Author(s):  
K. Wallden ◽  
R. Williams ◽  
J. Yan ◽  
P. W. Lian ◽  
L. Wang ◽  
...  
Keyword(s):  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Core Complex ◽  
The Core ◽  
Type Iv

scholarly journals Structural analysis of the Legionella pneumophila Dot/Icm Type IV Secretion System Core Complex

2020 ◽  
Author(s):  
Clarissa L. Durie ◽  
Michael J. Sheedlo ◽  
Jeong Min Chung ◽  
Brenda G. Byrne ◽  
Min Su ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Structural Features ◽  
Secretion System ◽  
Effector Proteins ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Type Iv Secretion System ◽  
Core Complex ◽  
The Core ◽  
Type Iv

AbstractLegionella pneumophila is an opportunistic pathogen that causes the potentially fatal pneumonia Legionnaires’ Disease. This infection and subsequent pathology require the Dot/Icm Type IV Secretion System (T4SS) to deliver effector proteins into host cells. Compared to prototypical T4SSs, the Dot/Icm assembly is much larger, containing ~27 different components including a core complex reported to be composed of five proteins: DotC, DotD, DotF, DotG, and DotH. Using single particle cryo-electron microscopy (cryo-EM), we report reconstructions of the core complex of the Dot/Icm T4SS that includes a symmetry mismatch between distinct structural features of the outer membrane cap (OMC) and periplasmic ring (PR). We present models of known core complex proteins, DotC, DotD, and DotH, and two structurally similar proteins within the core complex, DotK and Lpg0657. This analysis reveals the stoichiometry and contact interfaces between the key proteins of the Dot/Icm T4SS core complex and provides a framework for understanding a complex molecular machine.

scholarly journals Membrane and Core Periplasmic Agrobacterium tumefaciens Virulence Type IV Secretion System Components Localize to Multiple Sites around the Bacterial Perimeter during Lateral Attachment to Plant Cells

mBio ◽  
2011 ◽  
Vol 2 (6) ◽  
Author(s):  
Julieta Aguilar ◽  
Todd A. Cameron ◽  
John Zupan ◽  
Patricia Zambryski
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Plant Cells ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Host Cells ◽  
Type Iv Secretion System ◽  
Secretion Systems ◽  
Content Type ◽  
Protein Substrates ◽  
Type Iv

ABSTRACTType IV secretion systems (T4SS) transfer DNA and/or proteins into recipient cells. Here we performed immunofluorescence deconvolution microscopy to localize the assembled T4SS by detection of its native components VirB1, VirB2, VirB4, VirB5, VirB7, VirB8, VirB9, VirB10, and VirB11 in the C58 nopaline strain ofAgrobacterium tumefaciens, following induction of virulence (vir) gene expression. These different proteins represent T4SS components spanning the inner membrane, periplasm, or outer membrane. Native VirB2, VirB5, VirB7, and VirB8 were also localized in theA. tumefaciensoctopine strain A348. Quantitative analyses of the localization of all the above Vir proteins in nopaline and octopine strains revealed multiple foci in single optical sections in over 80% and 70% of the bacterial cells, respectively. Green fluorescent protein (GFP)-VirB8 expression followingvirinduction was used to monitor bacterial binding to live host plant cells; bacteria bind predominantly along their lengths, with few bacteria binding via their poles or subpoles.vir-induced attachment-defective bacteria or bacteria without the Ti plasmid do not bind to plant cells. These data support a model where multiplevir-T4SS around the perimeter of the bacterium maximize effective contact with the host to facilitate efficient transfer of DNA and protein substrates.IMPORTANCETransfer of DNA and/or proteins to host cells through multiprotein type IV secretion system (T4SS) complexes that span the bacterial cell envelope is critical to bacterial pathogenesis. Early reports suggested that T4SS components localized at the cell poles. Now, higher-resolution deconvolution fluorescence microscopy reveals that all structural components of theAgrobacterium tumefaciens vir-T4SS, as well as its transported protein substrates, localize to multiple foci around the cell perimeter. These results lead to a new model ofA. tumefaciensattachment to a plant cell, whereA. tumefacienstakes advantage of the multiplevir-T4SS along its length to make intimate lateral contact with plant cells and thereby effectively transfer DNA and/or proteins through thevir-T4SS. The T4SS ofA. tumefaciensis among the best-studied T4SS, and the majority of its components are highly conserved in different pathogenic bacterial species. Thus, the results presented can be applied to a broad range of pathogens that utilize T4SS.

scholarly journals Native structure of a type IV secretion system core complex essential for Legionella pathogenesis

2014 ◽  
Vol 111 (32) ◽  
pp. 11804-11809 ◽  
Author(s):  
T. Kubori ◽  
M. Koike ◽  
X. T. Bui ◽  
S. Higaki ◽  
S.-I. Aizawa ◽  
...  
Keyword(s):  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Native Structure ◽  
Core Complex ◽  
Type Iv

scholarly journals Agrobacterium tumefaciens VirB9, an Outer-Membrane-Associated Component of a Type IV Secretion System, Regulates Substrate Selection and T-Pilus Biogenesis

2005 ◽  
Vol 187 (10) ◽  
pp. 3486-3495 ◽  
Author(s):  
Simon J. Jakubowski ◽  
Eric Cascales ◽  
Vidhya Krishnamoorthy ◽  
Peter J. Christie
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Outer Membrane ◽  
Secretion System ◽  
Type Iv Secretion ◽  
Type Iv Secretion System ◽  
Substrate Selection ◽  
Inner Membrane ◽  
Protein Substrates ◽  
Type Iv ◽  
Pilus Biogenesis

ABSTRACT Agrobacterium tumefaciens translocates DNA and protein substrates between cells via a type IV secretion system (T4SS) whose channel subunits include the VirD4 coupling protein, VirB11 ATPase, VirB6, VirB8, VirB2, and VirB9. In this study, we used linker insertion mutagenesis to characterize the contribution of the outer-membrane-associated VirB9 to assembly and function of the VirB/D4 T4SS. Twenty-five dipeptide insertion mutations were classified as permissive for intercellular substrate transfer (Tra+), completely transfer defective (Tra−), or substrate discriminating, e.g., selectively permissive for transfer only of the oncogenic transfer DNA and the VirE2 protein substrates or of a mobilizable IncQ plasmid substrate. Mutations inhibiting transfer of DNA substrates did not affect formation of close contacts of the substrate with inner membrane channel subunits but blocked formation of contacts with the VirB2 and VirB9 channel subunits, which is indicative of a defect in assembly or function of the distal portion of the secretion channel. Several mutations in the N- and C-terminal regions disrupted VirB9 complex formation with the outer-membrane-associated lipoprotein VirB7 or the inner membrane energy sensor VirB10. Several VirB9.i2-producing Tra+ strains failed to elaborate T pilus at detectable levels (Pil−), and three such Tra+ Pil− mutant strains were rendered Tra− upon deletion of virB2, indicating that the cellular form of pilin protein is essential for substrate translocation. Our findings, together with computer-based analyses, support a model in which distinct domains of VirB9 contribute to substrate selection and translocation, establishment of channel subunit contacts, and T-pilus biogenesis.

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