Transcription of the Transfer Genes traY and traM of the Antibiotic Resistance Plasmid R100-1 Is Linked

Stockwell, David T.; Lelianova, Vera G.; Thompson, Teresa; Dempsey, Walter B.

doi:10.1006/plas.1999.1435

Cited by 5 publications

(4 citation statements)

References 30 publications

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“…Northern blot and primer extension analyses of traM and traJ mRNA suggest that transcription of both genes is derepressed throughout the growth curve in hns mutant strains, whereas transcription in wild‐type cells occurs only briefly in early exponential phase. Furthermore, a number of larger transcripts were detected in the hns mutant, which suggests that the traM promoters drive readthrough transcription into traJ and beyond, as suggested previously in the F‐like plasmid, R100 (Stockwell et al ., 2000). H‐NS appears to limit this readthrough, isolating the transcription of traM and traJ .…”

Section: Discussionsupporting

confidence: 77%

The role of H‐NS in silencing F transfer gene expression during entry into stationary phase

Will

Frost

2004

Molecular Microbiology

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SummaryThe conjugative ability of the F plasmid of Escherichia coli is highly growth phase dependent, with plasmid transfer efficiency dropping rapidly as donor cells progress through the growth cycle towards stationary phase. Transfer is dependent on the expression of the plasmid transfer ( tra ) genes, which are controlled by three plasmid-encoded regulatory proteins: TraJ, TraY and TraM. Here, we show that the nucleoid-associated host protein, H-NS, acts to repress the expression of traM and traJ as cells enter stationary phase, thereby decreasing mating ability to barely detectable levels. Sequence analysis identified regions of predicted intrinsic curvature, to which H-NS preferentially binds, at the promoters of both traM and traJ . H-NS binding at these regions was then confirmed by electrophoretic mobility shift and DNase I protection footprinting assays. Immunoblot assays displayed a significant increase in TraJ and TraM levels in an hns mutant strain. These findings were further supported by Northern and primer extension analyses which showed that whereas both genes were only expressed in early exponential phase in wild-type cells, hns mutant cells exhibited drastic derepression throughout the growth cycle. Transcriptional fusion studies of the individual promoters demonstrated that H-NS-mediated repression was observed when the promoters of both traM and traJ were present in cis to each other. This suggests that H-NS may bind to an extended region of the F plasmid, acting as a regional silencer of promoters for traJ and traM .

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Section: Discussionsupporting

confidence: 77%

The role of H‐NS in silencing F transfer gene expression during entry into stationary phase

Will

Frost

2004

Molecular Microbiology

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“…The TraY protein, encoded by the first gene of the tra operon, is a sequencespecific DNA binding protein with binding sites in cognate oriT and P Y promoter regions (15,28). TraY participates in DNA processing for transfer (17,27) and has been identified as a positive regulator of traM transcription (30,42). Furthermore, it has been proposed that TraY is involved in transcriptional regulation of the tra operon, where it presumably acts as a repressor as reported for plasmid R100 (45).…”

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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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“…Identification of the pSLT promoter under ArcAB control: quantitative reverse transcriptase-PCR analysis of traY mRNA: The product of the first gene of the tra operon (traY) has been shown to undergo autogenous control of tra operon transcription in the F sex factor (Silverman and Sholl 1996;Lum et al 2002) and in R100 (Stockwell et al 2000). Evidence that TraY is an autogenous activator of the tra operon also exists in pSLT (unpublished data from our laboratory).…”

Section: Arcamentioning

confidence: 93%

“…For instance, synthesis of TraJ, the main transcriptional activator of the tra operon, is controlled by the FinOP system of fertility inhibition (Frost et al 1994;Firth et al 1996). Regulatory feedback loops involving the TraM, TraJ, and TraY plasmid products also contribute to autogenous control of tra operon expression (Penfold et al 1996;Polzleitner et al 1997;Stockwell et al 2000).…”

mentioning

confidence: 99%

Regulation of Bacterial Conjugation in Microaerobiosis by Host-Encoded Functions ArcAB and SdhABCD

Serna¹,

Espinosa

Camacho³

et al. 2010

Genetics

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The virulence plasmid of Salmonella enterica (pSLT) is an F-like conjugative plasmid. High rates of pSLT transfer occur in the mammalian gut, a microaerobic environment. In this study, we describe genetic screens for host-encoded activators and repressors of the transfer operon (tra) of pSLT. We show that the transcription factor ArcA is an activator of conjugation, especially under microaerobiosis. In turn, succinate dehydrogenase (SdhABCD) is a repressor of mating in aerobiosis. ArcA binds upstream of the main tra promoter (p traY ) and activates tra transcription, as previously described in F, R1, and R100. In the absence of ArcA, transfer of pSLT decreased 7-fold in aerobiosis and .100-fold in microaerobiosis. In aerobiosis, ArcA activates the traY promoter in an ArcB-independent manner, as described in other F-like plasmids. In microaerobiosis, however, the ArcB sensor is necessary for activation of p traY . Lack of Sdh causes a .20-fold increase in pSLT transfer in aerobiosis, but has little effect under microaerobiosis. Sdh inhibits conjugal transfer by reducing traJ transcription, probably in an indirect manner. In turn, the sdhCDAB operon is repressed by the ArcAB system under microaerobiosis. Hence, the ArcAB twocomponent system of S. enterica stimulates pSLT transfer under microaerobiosis by two concerted actions: activation of the tra operon and repression of the sdhCDAB operon.

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Transcription of the Transfer Genes traY and traM of the Antibiotic Resistance Plasmid R100-1 Is Linked

Cited by 5 publications

References 30 publications

The role of H‐NS in silencing F transfer gene expression during entry into stationary phase

The role of H‐NS in silencing F transfer gene expression during entry into stationary phase

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

Regulation of Bacterial Conjugation in Microaerobiosis by Host-Encoded Functions ArcAB and SdhABCD

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