The<i>Agrobacterium</i>T-DNA Transport Pore Proteins VirB8, VirB9, and VirB10 Interact with One Another

Das, Anath Bandhu; Xie, Yun

doi:10.1128/jb.182.3.758-763.2000

Cited by 112 publications

(157 citation statements)

References 31 publications

(34 reference statements)

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“…Further investigations exploring these stabilizing effects, as well as recent cell biology studies, have led to the development of a biogenesis pathway for this transfer apparatus 22,53 .A crucial intermediate in this pathway is a 'core' structure that is composed of VirB4, VirB7-VirB10 and, probably, VirB6. The existence of this structure is now supported by data from dihybrid screens and complementary biochemical assays [54][55][56][57][58][59] (Table 2). Additionally, some of the interactions required for assembly of the putative core are conserved in the B. pertussis Ptl system.…”

Section: The Transenvelope Mpf Structurementioning

confidence: 80%

The versatile bacterial type IV secretion systems

Cascales¹,

Christie²

2003

Nat Rev Microbiol

588

556

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Bacteria use type IV secretion systems for two fundamental objectives related to pathogenesisgenetic exchange and the delivery of effector molecules to eukaryotic target cells. Whereas gene acquisition is an important adaptive mechanism that enables pathogens to cope with a changing environment during invasion of the host, interactions between effector and host molecules can suppress defence mechanisms, facilitate intracellular growth and even induce the synthesis of nutrients that are beneficial to bacterial colonization. Rapid progress has been made towards defining the structures and functions of type IV secretion machines, identifying the effector molecules, and elucidating the mechanisms by which the translocated effectors subvert eukaryotic cellular processes during infection. The year 2003 marks the fiftieth anniversary of the first description of a TYPE IV SECRETION (T4S)SYSTEM: the CONJUGATION apparatus of the F plasmid 1 . This is a dynamic bacterial surface organelle, the activities of which are now known to include the contact-dependent delivery of DNA to bacterial recipients and the assembly and retraction of a conjugal PILUS 2 . In the past decade, reports describing systems that are ancestrally related to the F-transfer system and other conjugation machines have emerged. Instead of mediating DNA transfer between bacteria, these systems deliver DNA or protein substrates, known as effectors, to eukaryotic target cells during infection [3][4][5] . More recently, several new T4S systems have been described that are also ancestrally related to the conjugation machines, but these systems mediate the exchange of DNA with the extracellular milieu [6][7][8] . Collectively, this diversity of function in the face of a common ancestry makes the T4S machines attractive subjects for comparative studies that explore the dynamics of organelle assembly and action. Additionally, from a medical perspective, it is of enormous interest to develop a detailed understanding of how the inter-kingdom transfer of type IV effector molecules contributes to pathogenesis. This review will summarize the recent advances in our knowledge of T4S, NIH Public Access Author ManuscriptNat Rev Microbiol. Author manuscript; available in PMC 2013 December 27. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscriptwith an emphasis on machine structure and function, and the activities of effectors after translocation into the eukaryotic host. The T4S familyThis fascinatingly versatile translocation family can be classified into three subfamilies, each of which contributes in unique ways to pathogenesis ( Fig. 1; Table 1). The largest subfamily, the conjugation systems, are found in most species of Gram-negative and Grampositive bacteria. These systems mediate DNA transfer both within and between phylogenetically diverse species, and some systems even deliver DNA to fungi, plants and human cells 2,9-13 . Conjugation is an important contributor to genome plasticity, and therefore bacterial fitness under changing en...

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Section: The Transenvelope Mpf Structurementioning

confidence: 80%

The versatile bacterial type IV secretion systems

Cascales¹,

Christie²

2003

Nat Rev Microbiol

588

556

View full text Add to dashboard Cite

show abstract

“…Addi- Table 2 Interactions between VirB/VirD4 components a B, detected biochemically (in vitro); G, suggested by genetic arrangement; H, detected by two-hybrid interaction analysis; O, suggested by other indirect evidence. Citations: 1 Spudich et al (1996); 15 Anderson et al (1996); 16 Farizo et al (1996); 17 Harris et al (2001); 18 Das et al (1997); 19 Das and Xie (2000); 20 Kumar and Das (2001); 21 Gilmour et al (2003); 22 Llosa et al (2003); 23 Krause et al (2000a); 24 Yeo et al (2000); 25 Hormaeche et al (2002); 26 Schröder et al (2002); 27 Kumar and Das (2002).…”

Section: Virb2: the Structural Subunit Of Pilimentioning

confidence: 99%

The mating pair formation system of conjugative plasmids—A versatile secretion machinery for transfer of proteins and DNA

Schröder

Lanka

2005

Plasmid

186

143

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The mating pair formation (Mpf) system functions as a secretion machinery for intercellular DNA transfer during bacterial conjugation. The components of the Mpf system, comprising a minimal set of 10 conserved proteins, form a membrane-spanning protein complex and a surface-exposed sex pilus, which both serve to establish intimate physical contacts with a recipient bacterium. To function as a DNA secretion apparatus the Mpf complex additionally requires the coupling protein (CP). The CP interacts with the DNA substrate and couples it to the secretion pore formed by the Mpf system. Mpf/CP conjugation systems belong to the family of type IV secretion systems (T4SS), which also includes DNA-uptake and -release systems, as well as eVector protein translocation systems of bacterial pathogens such as Agrobacterium tumefaciens (VirB/VirD4) and Helicobacter pylori (Cag). The increased eVorts to unravel the molecular mechanisms of type IV secretion have largely advanced our current understanding of the Mpf/CP system of bacterial conjugation systems. It has become apparent that proteins coupled to DNA rather than DNA itself are the actively transported substrates during bacterial conjugation. We here present a uniWed and updated view of the functioning and the molecular architecture of the Mpf/CP machinery. 

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“…VirB8 interactions with VirB9 and VirB10 were suggested with the yeast two-hybrid screen. 38,39 Additionally, VirB8 production appears to nucleate assembly of a VirB8, VirB9, VirB10 complex in A. tumefaciens. 40 VirB8 was shown to interact with the VirB1 putative transglycosylase.…”

Section: Structure-function Relationshipsmentioning

confidence: 99%

Agrobacterium tumefaciens VirB6 Domains Direct the Ordered Export of a DNA Substrate Through a Type IV Secretion System

Jakubowski

Krishnamoorthy

Cascales

et al. 2004

Journal of Molecular Biology

108

127

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The Agrobacterium tumefaciens VirB/D4 type IV secretion system (T4SS) translocates DNA and protein substrates across the bacterial cell envelope. Six presumptive channel subunits of this T4SS (VirD4, VirB11, VirB6, VirB8, VirB2, and VirB9) form close contacts with the VirD2-Tstrand transfer intermediate during export, as shown recently by a novel transfer DNA immunoprecipitation (TrIP) assay. Here, we characterize the contribution of the hydrophobic channel component VirB6 to substrate translocation. Results of reporter protein fusion and cysteine accessibility studies support a model for VirB6 as a polytopic membrane protein with a periplasmic N terminus, five transmembrane segments, and a cytoplasmic C terminus. TrIP studies aimed at characterizing the effects of VirB6 insertion and deletion mutations on substrate translocation identified several VirB6 functional domains: (i) a central region composed of a large periplasmic loop (P2) (residues 84 to 165) mediates the interaction of VirB6 with the exiting Tstrand; (ii) a multi-membrane-spanning region carboxyl-terminal to loop P2 (residues 165 to 245) is required for substrate transfer from VirB6 to the bitopic membrane subunit VirB8; and (iii) the two terminal regions (residues 1 to 64 and 245 to 290) are required for substrate transfer to the periplasmic and outer membrane-associated VirB2 and VirB9 subunits. Our findings support a model whereby the periplasmic loop P2 comprises a portion of the secretion channel and distinct domains of VirB6 participate in channel subunit interactions required for substrate passage to the cell exterior.

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TheAgrobacteriumT-DNA Transport Pore Proteins VirB8, VirB9, and VirB10 Interact with One Another

Cited by 112 publications

References 31 publications

The versatile bacterial type IV secretion systems

The versatile bacterial type IV secretion systems

The mating pair formation system of conjugative plasmids—A versatile secretion machinery for transfer of proteins and DNA

Agrobacterium tumefaciens VirB6 Domains Direct the Ordered Export of a DNA Substrate Through a Type IV Secretion System

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