Differential mRNA decay within the transfer operon of plasmid R1: identification and analysis of an intracistronic mRNA stabilizer

Koraimann, Günther; Teferle, Karin; Mitteregger, R; Wagner, Stephen J.; Högenauer, Gregor

doi:10.1007/bf02174035

Cited by 5 publications

(5 citation statements)

References 50 publications

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“…Our experimental setup was designed to allow induction of HSPs by heat shock and concomitant shift of groEL(Ts) cells to the restrictive temperature of 43°C (for details see Materials and Methods). For the investigation of the tra transcript levels we used a probe specific for the stable region of the tra transcript, which comprises the traA coding sequence and the 5Ј region of the traL coding region (18,21). At 22°C no conjugative DNA transfer was detectable in wildtype and groEL(Ts) cells and no traA transcripts were detectable ( Fig.…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2007

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Transcription of DNA transfer genes is a prerequisite for conjugative DNA transfer of F-like plasmids. Transfer gene expression is sensed by the donor cell and is regulated by a complex network of plasmid-and host-encoded factors. In this study we analyzed the effect of induction of the heat shock regulon on transfer gene expression and DNA transfer in Escherichia coli. Raising the growth temperature from 22°C to 43°C transiently reduced transfer gene expression to undetectable levels and reduced conjugative transfer by 2 to 3 orders of magnitude. In contrast, when host cells carried the temperature-sensitive groEL44 allele, heat shock-mediated repression was alleviated. These data implied that the chaperonin GroEL was involved in negative regulation after heat shock. Investigation of the role of GroEL in this regulatory process revealed that, in groEL(Ts) cells, TraJ, the plasmid-encoded master activator of type IV secretion (T4S) system genes, was less susceptible to proteolysis and had a prolonged half-life compared to isogenic wild-type E. coli cells. This result suggested a direct role for GroEL in proteolysis of TraJ, down-regulation of T4S system gene expression, and conjugation after heat shock. Strong support for this novel role for GroEL in regulation of bacterial conjugation was the finding that GroEL specifically interacted with TraJ in vivo. Our results further suggested that in wild-type cells this interaction was followed by rapid degradation of TraJ whereas in groEL(Ts) cells TraJ remained trapped in the temperature-sensitive GroEL protein and thus was not amenable to proteolysis.

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Section: Resultsmentioning

confidence: 99%

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

et al. 2007

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“…mRNA of the 33‐kb transfer operon of plasmid R1 decays non‐uniformly [34]. Processing of the polycistronic primary transcript leads to accumulation of traA mRNA which encodes a propilin, the precursor of pilin – the major subunit of sex pili.…”

Section: The F‐like Transfer Systemsmentioning

confidence: 99%

Control of genes for conjugative transfer of plasmids and other mobile elements

1998

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Conjugative transfer is a primary means of spread of mobile genetic elements (plasmids and transposons) between bacteria.It leads to the dissemination and evolution of the genes (such as those conferring resistance to antibiotics) which are carried by the plasmid. Expression of the plasmid genes needed for conjugative transfer is tightly regulated so as to minimise the burden on the host. For plasmids such as those belonging to the IncP group this results in downregulation of the transfer genes once all bacteria have a functional conjugative apparatus. For F-like plasmids (apart from F itself which is a derepressed mutant) tight control results in very few bacteria having a conjugative apparatus. Chance encounters between the rare transfer-proficient bacteria and a potential recipient initiate a cascade of transfer which can continue until all potential recipients have acquired the plasmid. Other systems express their transfer genes in response to specific stimuli. For the pheromone-responsive plasmids of Enterococcus it is small peptide signals from potential recipients which trigger the conjugative transfer genes. For the Ti plasmids of Agrobacterium it is the presence of wounded plants which are susceptible to infection which stimulates T-DNA transfer to plants. Transfer and integration of T-DNA induces production of opines which the plasmid-positive bacteria can utilise. They multiply and when they reach an appropriate density their plasmid transfer system is switched on to allow transfer of the Ti plasmid to other bacteria. Finally some conjugative transfer systems are induced by the antibiotics to which the elements confer resistance. Understanding these control circuits may help to modify management of microbial communities where plasmid transfer is either desirable or undesirable. z 1998 Published by Elsevier Science B.V.

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“…traA is the second gene in the tra operon. We have observed that the traA portion of the polycistronic mRNA is particularly stable (Koraimann and Hö genauer, 1989;Koraimann et al, 1996a). Steadystate levels of traA mRNA from R1-16 can therefore be readily measured, and we have adopted this measurement as an indicator of tra operon promoter activity.…”

Section: Construction Of the Tram Mutationsmentioning

confidence: 99%

“…Quantification of several mRNA species at the same time was performed as described previously (Koraimann et al, 1996a) according to O'Donovan et al (1991). Four oligonucleotides were used; the first one, designated TRAA2, was complementary to the traA mRNA.…”

Section: Rna-oligonucleotide Protection Experimentsmentioning

confidence: 99%

TraM of plasmid R1 controls transfer gene expression as an integrated control element in a complex regulatory network

Pölzleitner

Zechner

Renner

et al. 1997

Molecular Microbiology

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SummarySite-directed mutagenesis was used to investigate the functions of the traM gene in plasmid R1-mediated bacterial conjugation. Three mutant alleles, a null mutation, a sense mutation and a stop mutation, were recombined back into the R1-16 plasmid, a transferderepressed (finO ¹ ) variant of plasmid R1. The frequency of conjugative transfer of the traM null mutant derivative of R1-16 was 10 7 -fold lower than that of the isogenic parent plasmid, showing the absolute requirement for this gene in conjugative transfer of plasmid R1. Measurements of the abundance of plasmid specified traJ, traA and traM mRNAs, TraM protein levels, and complementation studies indicated that the traM gene of plasmid R1 has at least two functions in conjugation: (i) positive control of transfer gene expression; and (ii) a function in a process distinct from gene expression. Since expression of the negatively autoregulated traM gene is itself affected positively by the expression of the transfer operon genes, this gene constitutes a decisive element within a regulatory circuit that co-ordinates expression of the genes necessary for horizontal DNA transfer. Based on our studies, we present a novel model for the regulation of the transfer genes of plasmid R1 that might also be applicable to other IncF plasmids.

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Differential mRNA decay within the transfer operon of plasmid R1: identification and analysis of an intracistronic mRNA stabilizer

Cited by 5 publications

References 50 publications

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

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

Control of genes for conjugative transfer of plasmids and other mobile elements

TraM of plasmid R1 controls transfer gene expression as an integrated control element in a complex regulatory network

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