The Positive Regulator, TraJ, of the Escherichia coli F Plasmid Is Unstable in a cpxA* Background

AUTOR(ES)

Gubbins, Michael J.

FONTE

American Society for Microbiology

RESUMO

The Cpx (conjugative plasmid expression) stress response of Escherichia coli is induced in response to extracytoplasmic signals generated in the cell envelope, such as misfolded proteins in the periplasm. Detection of stress is mediated by the membrane-bound histidine kinase, CpxA. Signaling of the response regulator CpxR by activated CpxA results in the expression of several factors required for responding to cell envelope stress. CpxA was originally thought to be required for the expression of the positive regulator of the F plasmid transfer (tra) operon, TraJ. It was later determined that constitutive gain-of-function mutations in cpxA led to activation of the Cpx envelope stress response and decreased TraJ expression. In order to determine the nature of the downregulation of TraJ, the level of expression of TraJ, TraM, and TraY, the F-encoded regulatory proteins of the F tra region, was determined both in a cpxA* background and in a wild-type background in which the Cpx stress response was induced by overexpression of the outer membrane lipoprotein, NlpE. Our results suggest that TraJ downregulation is controlled by a posttranscriptional mechanism that operates in the cytoplasm in response to upregulation of the Cpx stress response by both the cpxA* gain-of-function mutation and the overexpression of NlpE.

Documentos Relacionados

• Accumulation of the F plasmid TraJ protein in cpx mutants of Escherichia coli.
• Cpx Two-Component Signal Transduction in Escherichia coli: Excessive CpxR-P Levels Underlie CpxA* Phenotypes
• traJ independence in expression of traT on F.
• Nucleotide sequences of the R1-19 plasmid transfer genes traM, finP, traJ, and traY and the traYZ promoter.
• Aberrant Cell Division and Random FtsZ Ring Positioning in Escherichia coli cpxA* Mutants