Characterisation of a Pseudomonas aeruginosa twitching motility gene and evidence for a specialised protein export system widespread in eubacteria

Whitchurch, Cynthia B.; Hobbs, Matthew; Livingston, S. P.; Krishnapillai, V.; Mattick, John S.

doi:10.1016/0378-1119(91)90221-v

Cited by 271 publications

(247 citation statements)

References 59 publications

Supporting

Mentioning

241

Contrasting

Order By: Relevance

“…The two proteins have a very similar distribution in the subcellular fractions, indicating that they might interact with one another. In addition, the VirB11 NTP-binding domain is homologous to those of at least four other proteins that are involved in the translocation of macromolecules across the membrane: the competence protein, ComG, of Bacillus subtilis (1); the protein secretion gene in Xanthomonas campestris (15); the pullulanase secretion gene in Kiebsiella oxytoca (37); and the twitching motility gene in Pseudomonas aeruginosa (58).…”

Section: Discussionmentioning

confidence: 99%

Subcellular localization of seven VirB proteins of Agrobacterium tumefaciens: implications for the formation of a T-DNA transport structure

1993

View full text Add to dashboard Cite

Plant cell transformation by Agrobacteriwun Iwefaciens involves the transfer of a single-stranded DNAprotein complex (T-complex) from the bacterium to the plant cell. One of the least understood and important aspects of this process is how the T-complex exits the bacterium. The eleven virB gene products have been proposed to specify the DNA export channel on the basis of their predicted hydrophobicity. To determine the cellular localization of the VirB proteins, two different cell fractionation methods were employed to separate inner and outer membranes. Seven VirB-specific antibodies were used on Western blots (immunoblots) to detect the proteins in the inner and outer membranes and soluble (containing cytoplasm and periplasm) fractions. VirB5 was in both the inner membrane and cytoplasm. Six of the VwrB proteins were detected in the membrane fractions only. Three of these, VWrB8, VirB9, and VWrBlO, were present in both inner and outer membrane fractions regardless of the fractionation method used. Three additional VwrB proteins, VirBi, VWrB4, and VWrB1I, were found mainly in the inner membrane fraction by one method and were found in both inner and outer membrane fractions by a second method. These results confirm the membrane localization of seven VirB proteins and strengthen the hypothesis that VirB proteins are involved in the formation of a T-DNA export channel or gate. That most of the VwrB proteins analyzed are found in both inner and outer membrane fractions suggest that they form a complex pore structure that spans both membranes, and their relative amounts in the two membrane fractions reflect their differential sensitivity to the experimental conditions. Agrobacterium tumefaciens has the unique ability to transfer DNA to plant cells. In nature, the transfer and expression of a specific fragment of DNA (T-DNA) cause a neoplastic growth on the plant host. In the laboratory, this DNA transfer phenomenon has been exploited by using disarmed vectors to introduce new genes into plants. The T-DNA and the components necessary for packaging and transfer of the single-stranded T-DNA (T-strand) (45) are encoded by the tumor-inducing (Ti) plasmid in A. tumefaciens. The virulence (vir) region contains four operons (virA, virG, virD, and virB) that encode proteins required for virulence on all hosts (44). Three additional operons (virE, virC, and virH) encode proteins that are required only on some hosts (25,44).The transfer of DNA from the bacterium to the plant cell involves at least seven recognizable steps. Of the bacterial components necessary for DNA transfer, only the first step is thought to be mediated by chromosomally encoded functions (reviewed in reference 5). The remaining steps involve proteins that are encoded by the vir region on the Ti plasmid (reviewed in reference 59). The seven steps are as follows: (i) the bacterium binds to a specific component of the plant cell surface; (ii) a bacterial membrane protein (VirA) recognizes signals released by a wounded plant cell and transduces the signal v...

show abstract

Section: Discussionmentioning

confidence: 99%

Subcellular localization of seven VirB proteins of Agrobacterium tumefaciens: implications for the formation of a T-DNA transport structure

1993

View full text Add to dashboard Cite

show abstract

“…VirB11 belongs to the family of PulE-like NTPases found in type II, type IV and tad-like secretion systems (Motallebi-Veshareh et al, 1992;Planet et al, 2001;Whitchurch et al, 1991). Along with VirB4 and the CP (VirD4), VirB11 is thought to energize the type IV secretion machinery either for complex assembly, pilus production and/or substrate secretion.…”

Section: Virb11: a Ring-shaped Cytoplasmic Ntpase Fuelling The Secretmentioning

confidence: 99%

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

Schröder

Lanka

2005

Plasmid

190

146

View full text Add to dashboard Cite

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. 

show abstract

“…T2SS machineries share a common origin and architecture and functional properties with systems involved in type IV pilus assembly and retraction, DNA uptake, and natural competence (64). Central to these machineries is their ability to assemble and disassemble filaments that either remain periplasmic and function in protein secretion (pseudopili) or extend well beyond the cell surface and play a role in adhesion, surface motility, or microcolony or biofilm formation (type IV pili) (12).…”

mentioning

confidence: 99%

Signal Recognition Particle-Dependent Inner Membrane Targeting of the PulG Pseudopilin Component of a Type II Secretion System

et al. 2007

View full text Add to dashboard Cite

The pseudopilin PulG is an essential component of the pullulanase-specific type II secretion system from Klebsiella oxytoca. PulG is the major subunit of a short, thin-filament pseudopilus, which presumably elongates and retracts in the periplasm, acting as a dynamic piston to promote pullulanase secretion. It has a signal sequence-like N-terminal segment that, according to studies with green and red fluorescent protein chimeras, anchors unassembled PulG in the inner membrane. We analyzed the early steps of PulG inner membrane targeting and insertion in Escherichia coli derivatives defective in different protein targeting and export factors. The ␤-galactosidase activity in strains producing a PulG-LacZ hybrid protein increased substantially when the dsbA, dsbB, or all sec genes tested except secB were compromised by mutations. To facilitate analysis of native PulG membrane insertion, a leader peptidase cleavage site was engineered downstream from the N-terminal transmembrane segment (PrePulG*). Unprocessed PrePulG* was detected in strains carrying mutations in secA, secY, secE, and secD genes, including some novel alleles of secY and secD. Furthermore, depletion of the Ffh component of the signal recognition particle (SRP) completely abolished PrePulG* processing, without affecting the Sec-dependent export of periplasmic MalE and RbsB proteins. Thus, PulG is cotranslationally targeted to the inner membrane Sec translocase by SRP.

show abstract

Characterisation of a Pseudomonas aeruginosa twitching motility gene and evidence for a specialised protein export system widespread in eubacteria

Cited by 271 publications

References 59 publications

Subcellular localization of seven VirB proteins of Agrobacterium tumefaciens: implications for the formation of a T-DNA transport structure

Subcellular localization of seven VirB proteins of Agrobacterium tumefaciens: implications for the formation of a T-DNA transport structure

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

Signal Recognition Particle-Dependent Inner Membrane Targeting of the PulG Pseudopilin Component of a Type II Secretion System

Contact Info

Product

Resources

About