GroEL Plays a Central Role in Stress-Induced Negative Regulation of Bacterial Conjugation by Promoting Proteolytic Degradation of the Activator Protein TraJ

Zahrl, Doris; Wagner, Andrea; Tscherner, Michael; Koraimann, Günther

doi:10.1128/jb.00005-07

Cited by 29 publications

(25 citation statements)

References 53 publications

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“…4). This phenomenon can be explained by a negative feed-back loop that is induced by the massive tra gene expression which causes cellular stress followed by functional inactivation of TraJ (Zahrl et al, 2007). In addition, a reduction of tra gene expression can be seen at 90 min which we believe is also due to the abovementioned induction of cellular stress.…”

Section: H-ns Acts As a Silencer Of Transfer Gene Expressionmentioning

confidence: 94%

“…Plasmids with the correct sequence were used for further experiments. Expression of N-terminally FLAG-tagged TraJ proteins was verified by using SDS-PAGE and Western blotting as described previously (Zahrl et al, 2007).…”

Section: Methodsmentioning

confidence: 99%

“…N-terminally FLAG-tagged TraJ was expressed from the IPTG inducible plasmid pTGNF4 in a strain harbouring the Fin + R1 derivative pAR183. Basal (non-induced) expression of FLAG-TraJ from pTGNF4 increased the conjugation frequency of pAR183 to the levels of the de-repressed plasmid R1-16 (Zahrl et al, 2007). If FLAG-TraJ bound to P Y promoter of pAR183 DNA in vivo, immunoprecipitation of FLAG-TraJ should lead to a specific enrichment of P Y DNA.…”

Section: Traj Binds To P Y Promoter Dna In Vivomentioning

confidence: 99%

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Silencing and activating type IV secretion genes of the F-like conjugative resistance plasmid R1

et al. 2013

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Expression of DNA transfer (tra) genes of F-type conjugative plasmids is required for the assembly of a functional type IV secretion machinery and subsequent plasmid DNA transfer from donor to recipient cells. Transcription of tra genes depends on the activation of a single promoter, designated P Y , by the plasmid encoded TraJ protein. We here determine plasmid specificity of TraJ proteins from various subgroups of F-like plasmids and find that plasmid R1 conjugation and P Y promoter activation can be achieved only by its cognate activator and by TraJ of the Salmonella plasmid pSLT and not by F or R100 TraJ proteins. In addition, we characterize the P Y promoter of plasmid R1. We show that TraJ binds to P Y DNA in vivo and that H-NS acts as a silencer of the P Y promoter. In the natural plasmid context, H-NS silences transfer gene expression and horizontal plasmid DNA transfer. In contrast to what was found for the F plasmid, lack of H-NS did not abolish the requirement for ArcA and TraJ to reach full tra gene expression and DNA transfer activity. We propose that, besides a passive de-silencing activity, both ArcA and TraJ play a direct role in synergistically stimulating tra operon transcription and subsequent DNA transfer.

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Section: H-ns Acts As a Silencer Of Transfer Gene Expressionmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Section: Traj Binds To P Y Promoter Dna In Vivomentioning

confidence: 99%

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Silencing and activating type IV secretion genes of the F-like conjugative resistance plasmid R1

et al. 2013

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“…Moreover, in the latter protocol, the physical structure of the colony was altered daily by disrupting the extracellular polymeric matrix and possibly changing the intercellular distances, and cells were subjected to physical stresses due to resuspension by vortexing, centrifugation and replating on new filters. The effect of such stress factors on conjugation efficiencies has not been investigated, but recent studies have shown the importance of stress response mechanisms in conjugative gene transfer (Beaber et al, 2003;Zahrl et al, 2007). One additional caveat might be a slight loss of cells during every transfer due to the cell spreading procedure, which may affect plasmid dynamics.…”

Section: Discussionmentioning

confidence: 99%

Spatial structure and nutrients promote invasion of IncP-1 plasmids in bacterial populations

et al. 2008

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In spite of the importance of plasmids in bacterial adaptation, we have a poor understanding of their dynamics. It is not known if or how plasmids persist in and spread through (invade) a bacterial population when there is no selection for plasmid-encoded traits. Moreover, the differences in dynamics between spatially structured and mixed populations are poorly understood. Through a joint experimental/theoretical approach, we tested the hypothesis that self-transmissible IncP-1 plasmids can invade a bacterial population in the absence of selection when initially very rare, but only in spatially structured habitats and when nutrients are regularly replenished. Using protocols that differed in the degree of spatial structure and nutrient levels, the invasiveness of plasmid pB10 in Escherichia coli was monitored during at least 15 days, with an initial fraction of plasmid-bearing (p þ ) cells as low as 10 À7 . To further explore the mechanisms underlying plasmid dynamics, we developed a spatially explicit mathematical model. When cells were grown on filters and transferred to fresh medium daily, the p þ fraction increased to 13%, whereas almost complete invasion occurred when the population structure was disturbed daily. The plasmid was unable to invade in liquid. When carbon source levels were lower or not replenished, plasmid invasion was hampered.Simulations of the mathematical model closely matched the experimental results and produced estimates of the effects of alternative experimental parameters. This allowed us to isolate the likely mechanisms most responsible for the observations. In conclusion, spatial structure and nutrient availability can be key determinants in the invasiveness of plasmids.

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“…However, mobile elements in general also impose a metabolic burden, and to minimize the risk of killing the bacterial host, various mechanisms have evolved, by both the element and the prokaryotic host, to regulate propagation. Mechanisms controlling T4SS gene expression range from simple feedback systems monitoring intracellular levels of Dtr factors, e.g., relaxases, to more complex regulatory systems linking the cell envelope stress response or various environmental signals to T4SS gene expression (168,220,293,295). Other mechanisms that have evolved to control propagation operate at the level of replication (copy number control and incompatibility), partitioning, or entry exclusion (15,185,186,204).…”

Section: Modulation Of Lateral Gene Transfermentioning

confidence: 99%

Biological Diversity of Prokaryotic Type IV Secretion Systems

Martı́nez

Christie

2009

Microbiol Mol Biol Rev

623

780

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SUMMARY Type IV secretion systems (T4SS) translocate DNA and protein substrates across prokaryotic cell envelopes generally by a mechanism requiring direct contact with a target cell. Three types of T4SS have been described: (i) conjugation systems, operationally defined as machines that translocate DNA substrates intercellularly by a contact-dependent process; (ii) effector translocator systems, functioning to deliver proteins or other macromolecules to eukaryotic target cells; and (iii) DNA release/uptake systems, which translocate DNA to or from the extracellular milieu. Studies of a few paradigmatic systems, notably the conjugation systems of plasmids F, R388, RP4, and pKM101 and the Agrobacterium tumefaciens VirB/VirD4 system, have supplied important insights into the structure, function, and mechanism of action of type IV secretion machines. Information on these systems is updated, with emphasis on recent exciting structural advances. An underappreciated feature of T4SS, most notably of the conjugation subfamily, is that they are widely distributed among many species of gram-negative and -positive bacteria, wall-less bacteria, and the Archaea. Conjugation-mediated lateral gene transfer has shaped the genomes of most if not all prokaryotes over evolutionary time and also contributed in the short term to the dissemination of antibiotic resistance and other virulence traits among medically important pathogens. How have these machines adapted to function across envelopes of distantly related microorganisms? A survey of T4SS functioning in phylogenetically diverse species highlights the biological complexity of these translocation systems and identifies common mechanistic themes as well as novel adaptations for specialized purposes relating to the modulation of the donor-target cell interaction.

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GroEL Plays a Central Role in Stress-Induced Negative Regulation of Bacterial Conjugation by Promoting Proteolytic Degradation of the Activator Protein TraJ

Cited by 29 publications

References 53 publications

Silencing and activating type IV secretion genes of the F-like conjugative resistance plasmid R1

Silencing and activating type IV secretion genes of the F-like conjugative resistance plasmid R1

Spatial structure and nutrients promote invasion of IncP-1 plasmids in bacterial populations

Biological Diversity of Prokaryotic Type IV Secretion Systems

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