Isolation of Bacterial Type IV Machine Subassemblies

Sarkar, Mayukh K.; Husnain, Seyyed I.; Jakubowski, Simon J.; Christie, Peter J.

doi:10.1007/978-1-62703-245-2_12

Cited by 11 publications

(11 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Results of these studies led to the concept of the ‘core complex’, an intrinsically stable VirB7/B9/B10 subassembly that serves as a structural scaffold during machine biogenesis. Existence of this core complex has now been validated by detection of ring-shaped core complexes from A. tumefaciens by transmission electron microscopy [128] and high resolution structural analysis of the related E. coli pKM101-encoded TraN/O/F core complex by cryoelectron microscopy and X-ray crystallography (Fig. 4) [33, 34].…”

Section: The Outer Membrane Complex (Omc) and Corementioning

confidence: 99%

Mechanism and structure of the bacterial type IV secretion systems

Christie¹,

Whitaker²,

González-Rivera³

2014

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

Self Cite

242

209

View full text Add to dashboard Cite

The bacterial type IV secretion systems (T4SSs) translocate DNA and protein substrates to bacterial or eukaryotic target cells generally by a mechanism dependent on direct cell-to-cell contact. The T4SSs encompass two large subfamilies, the conjugation systems and the effector translocators. The conjugation systems mediate interbacterial DNA transfer and are responsible for the rapid dissemination of antibiotic resistance genes and virulence determinants in clinical settings. The effector translocators are used by many Gram-negative bacterial pathogens for delivery of potentially hundreds of virulence proteins to eukaryotic cells for modulation of different physiological processes during infection. Recently, there has been considerable progress in defining the structures of T4SS machine subunits and large machine subassemblies. Additionally, the nature of substrate translocation sequences and the contributions of accessory proteins to substrate docking with the translocation channel have been elucidated. A DNA translocation route through the Agrobacterium tumefaciens VirB/VirD4 system was defined, and both intracellular (DNA ligand, ATP energy) and extracellular (phage binding) signals were shown to activate type IV-dependent translocation. Finally, phylogenetic studies have shed light on the evolution and distribution of T4SSs, and complementary structure-function studies of diverse systems have identified adaptations tailored for novel functions in pathogenic settings. This review summarizes the recent progress in our understanding of the architecture and mechanism of action of these fascinating machines, with emphasis on the ‘archetypal’ A. tumefaciens VirB/VirD4 T4SS and related conjugation systems.

show abstract

Section: The Outer Membrane Complex (Omc) and Corementioning

confidence: 99%

Mechanism and structure of the bacterial type IV secretion systems

Christie¹,

Whitaker²,

González-Rivera³

2014

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

Self Cite

242

209

View full text Add to dashboard Cite

show abstract

“…The envelope-spanning core complex: In A. tumefaciens , the outer membrane lipoprotein VirB7, outer membrane-associated VirB9, and bitopic VirB10 stabilize each other as well as other VirB channel subunits (20), and evidence has been presented for assembly of these proteins as a ring-shaped complex now called the core complex (Figs. 3, 4) (61). An analogous core complex composed of the corresponding VirB homologs encoded by the conjugative plasmid pKM101 was structurally resolved by cryoelectron microscopy (CryoEM) and a portion was further solved by X-ray crystallography (62, 63).…”

Section: Ti Plasmid-encoded Type IV Secretion Systemsmentioning

confidence: 99%

The Agrobacterium Ti Plasmids

Gordon¹,

Christie²

2014

Microbiol Spectr

Self Cite

View full text Add to dashboard Cite

Agrobacterium tumefaciens is a plant pathogen with the capacity to deliver a segment of oncogenic DNA carried on a large plasmid called the tumor-inducing or Ti plasmid to susceptible plant cells. A. tumefaciens belongs to the class Alphaproteobacteria , whose members include other plant pathogens ( Agrobacterium rhizogenes ), plant and insect symbionts ( Rhizobium spp. and Wolbachia spp., respectively), human pathogens ( Brucella spp., Bartonella spp., Rickettsia spp.), and nonpathogens ( Caulobacter crescentus, Rhodobacter sphaeroides ). Many species of Alphaproteobacteria carry large plasmids ranging in size from ∼100 kb to nearly 2 Mb. These large replicons typically code for functions essential for cell physiology, pathogenesis, or symbiosis. Most of these elements rely on a conserved gene cassette termed repABC for replication and partitioning, and maintenance at only one or a few copies per cell ( 1 ). The subject of this review is the ∼200-kb Ti plasmids carried by infectious strains of A. tumefaciens . We will summarize the features of this plasmid as a representative of the repABC family of megaplasmids. We will also describe novel features of this plasmid that enable A. tumefaciens cells to incite tumor formation in plants, sense and respond to an array of plant host and bacterial signal molecules, and maintain and disseminate the plasmid among populations of agrobacteria. At the end of this review, we will describe how this natural genetic engineer has been adapted to spawn an entire industry of plant biotechnology and review its potential for use in future therapeutic applications of plant and nonplant species.

show abstract

“…Pathogenic bacteria of humans and plants have coopted conjugation systems to export virulence factors to eukaryotic host cells. Thanks to the efforts of Christie et al (Christie 2009;Sarkar et al 2013) and Waksman et al (Chandran et al 2009;Fronzes et al 2009a,b;RiveraCalzada et al 2013) we are now capable of describing the inner mechanics of the core complex (CC) and the effector delivery subsystem.…”

Section: The Type IV Secretion System Machinery: From the Inner Core mentioning

confidence: 99%