Temperature-Dependent Conjugative Transfer of R27: Role of Chromosome- and Plasmid-Encoded Hha and H-NS Proteins

Forns, Nuria; Baños, Rosa C.; Balsalobre, Carlos; Juárez, Antonio; Madrid, Cristina

doi:10.1128/jb.187.12.3950-3959.2005

Cited by 68 publications

(70 citation statements)

References 48 publications

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“…These results show that the Hha-YdgT proteins participate in the regulation of plasmid pSLT conjugation. The par- ticipation of Hha-like proteins in the modulation of conjugative plasmid transfer has also been reported previously for the IncH1 plasmid R27 (15). These results show that Hha-like proteins negatively modulate the expression of horizontally acquired genes in enteric bacteria, either directly or indirectly.…”

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confidence: 57%

Modulation of Horizontally Acquired Genes by the Hha-YdgT Proteins in Salmonella enterica Serovar Typhimurium

et al. 2008

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We describe a transcriptomic study of the effect of hha and ydgT mutations in Salmonella enterica serovar Typhimurium. A large number of genes showing altered expression are located in AT-rich horizontally acquired DNA sequences. Many of these genes have also been reported to be targets for H-NS. As Hha and YdgT interact with H-NS, our findings strongly suggest that Hha and/or YdgT must form complexes with H-NS when they silence these DNA regions.

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confidence: 57%

Modulation of Horizontally Acquired Genes by the Hha-YdgT Proteins in Salmonella enterica Serovar Typhimurium

et al. 2008

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“…The decreased transcript levels of an operon in Tra1 encoding non-Mpf proteins would indicate that a global temperature regulator is controlling R27 conjugation genes in the Tra1 and Tra2 region. A recent analysis of the effect of temperature on R27 transcription has revealed that H-NS and HhaA proteins have an inhibitory effect on the transcription of a number of Tra1 and Tra2 genes at 33 u C (Forns et al, 2005). A comprehensive analysis of the temperature regulation of each R27 transfer gene has been recently completed (Alonso et al, 2005).…”

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confidence: 99%

Subcellular localization and functional domains of the coupling protein, TraG, from IncHI1 plasmid R27

et al. 2005

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Bacterial conjugation is a horizontal gene transfer event mediated by the type IV secretion system (T4SS) encoded by bacterial plasmids. Within the T4SS, the coupling protein plays an essential role in linking the membrane-associated pore-forming proteins to the cytoplasmic, DNA-processing proteins. TraG is the coupling protein encoded by the incompatibility group HI plasmids. A hallmark feature of the IncHI plasmids is optimal conjugative transfer at 30 6C and an inability to transfer at 37 6C. Transcriptional analysis of the transfer region 1 (Tra1) of R27 has revealed that traG is transcribed in a temperature-dependent manner, with significantly reduced levels of expression at 37 6C as compared to expression at 30 6C. The R27 coupling protein contains nucleoside triphosphate (NTP)-binding domains, the Walker A and Walker B boxes, which are well conserved among this family of proteins. Site-specific mutagenesis within these motifs abrogated the conjugative transfer of R27 into recipient cells. Mutational analysis of the TraG periplasmic-spanning residues, in conjunction with bacterial two-hybrid and immunoprecipitation analysis, determined that this region is essential for a successful interaction with the T4SS protein TrhB. Further characterization of TraG by immunofluorescence studies revealed that the R27 coupling protein forms membrane-associated fluorescent foci independent of R27 conjugative proteins. These foci were found at discrete positions within the cell periphery. These results allow the definition of domains within TraG that are involved in conjugative transfer, and determination of the cellular location of the R27 coupling protein.

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“…In the case of R100, the Hha homolog, RmoA, has been shown to act as a positive regulator of transfer (39). Several IncH plasmids have been shown to carry both H-NS and Hha homologs (5,23), which appear to play a role in regulating plasmid transfer gene expression (16). We are currently investigating the mechanism of TraJ antagonism of H-NS to determine whether it occurs through binding DNA to disrupt a repressor complex or by binding H-NS directly, thereby affecting its activity.…”

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Characterization of the Opposing Roles of H-NS and TraJ in Transcriptional Regulation of the F-Plasmid tra Operon

Will

Frost

2006

J Bacteriol

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The transfer (tra) operon of the conjugative F plasmid of Escherichia coli is a polycistronic 33-kb operon which encodes most of the proteins necessary for F-plasmid transfer. Here, we report that transcription from P Y , the tra operon promoter, is repressed by the host nucleoid-associated protein, H-NS. Electrophoretic mobility shift assays indicate that H-NS binds preferentially to the tra promoter region, while Northern blot and transcriptional fusion analyses indicate that transcription of traY, the first gene in the tra operon, is derepressed in an hns mutant throughout growth. The plasmid-encoded regulatory protein TraJ is essential for transcription of the tra operon in wild-type Escherichia coli; however, TraJ is not necessary for plasmid transfer or traY operon transcription in an hns mutant. This indicates that H-NS represses transcription from P Y directly and not indirectly via its effects on TraJ levels. These results suggest that TraJ functions to disrupt H-NS silencing at P Y , allowing transcription of the tra operon.

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Temperature-Dependent Conjugative Transfer of R27: Role of Chromosome- and Plasmid-Encoded Hha and H-NS Proteins

Cited by 68 publications

References 48 publications

Modulation of Horizontally Acquired Genes by the Hha-YdgT Proteins in Salmonella enterica Serovar Typhimurium

Modulation of Horizontally Acquired Genes by the Hha-YdgT Proteins in Salmonella enterica Serovar Typhimurium

Subcellular localization and functional domains of the coupling protein, TraG, from IncHI1 plasmid R27

Characterization of the Opposing Roles of H-NS and TraJ in Transcriptional Regulation of the F-Plasmid tra Operon

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