Activation of the σE-dependent stress pathway by conjugative TraR may anticipate conjugational stress.
J Bacteriol
; 197(5): 924-31, 2015 Mar.
Article
em En
| MEDLINE
| ID: mdl-25535270
ABSTRACT
Horizontal gene transfer by conjugation plays a major role in bacterial evolution, allowing the acquisition of new traits, such as virulence and resistance to antibacterial agents. With the increased antibiotic resistance in bacterial pathogens, a better understanding of how bacteria modulate conjugation under changing environments and the genetic factors involved is needed. Despite the evolutionary advantages conjugation may confer, the process can be quite stressful for the donor cell. Here, we characterize the ability of TraR, encoded on the episomal F' plasmid, to upregulate the σ(E) extracytoplasmic stress pathway in Escherichia coli. TraR, a DksA homolog, modulates transcription initiation through the secondary channel of RNA polymerase. We show here that TraR activates transcription directly; however, unlike DksA, it does so without using ppGpp as a cofactor. TraR expression can stimulate the σ(E) extracytoplasmic stress response independently of the DegS/RseA signal transduction cascade. In the absence of TraR, bacteria carrying conjugative plasmids become more susceptible to external stress. We propose that TraR increases the concentrations of periplasmic chaperones and proteases by directly activating the transcription of σ(E)-dependent promoters; this increased protein folding capacity may prepare the bacterium to endure the periplasmic stress of sex pilus biosynthesis during mating.
Texto completo:
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Bases de dados:
MEDLINE
Assunto principal:
Fator sigma
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Fatores de Transcrição
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Regulação para Cima
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Conjugação Genética
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Proteínas de Escherichia coli
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Escherichia coli
Idioma:
En
Revista:
J Bacteriol
Ano de publicação:
2015
Tipo de documento:
Article
País de afiliação:
Estados Unidos