TY - JOUR
T1 - The extracytoplasmic stress factor, σE, is required to maintain cell envelope integrity in Escherichia coli
AU - Hayden, Jennifer D.
AU - Ades, Sarah E.
N1 - Funding Information:
We thank Susan Gottesman, Tracy Raivio, Carol Gross, Mark Goulian, and Hirotada Mori for sharing strains; Mary Laubacher for making strains; and Kathleen Postle, Marta Manning, and Charles Bulathsinghala for assistance with sucrose gradients and the FepA antibody. All fluorescence microscopy was done at the Cytometry Facility, University Park (Huck Institutes of the Life Sciences, Penn State University) and the facility is funded, in part, under a grant with the Pennsylvania Department of Health using Tobacco Settlement Funds. The Department specifically disclaims responsibility for any analyses, interpretations, or conclusions. All electron microscopy was done at the Electron Microscopy Facility at the Huck Institutes of the Life Sciences, Penn State University.
PY - 2008/2/6
Y1 - 2008/2/6
N2 - Extracytoplasmic function or ECF sigma factors are the most abundant class of alternative sigma factors in bacteria. Members of the rpoE subclass of ECF sigma factors are implicated in sensing stress in the cell envelope of Gram-negative bacteria and are required for virulence in many pathogens. The best-studied member of this family is rpoE from Escherichia coli, encoding the σE protein. σE has been well studied for its role in combating extracytoplasmic stress, and the members of its regulon have been largely defined. σE is required for viability of E coli, yet none of the studies to date explain why σE is essential in seemingly unstressed cells. In this work we investigate the essential role of σE in E coli by analyzing the phenotypes associated with loss of σE activity and isolating suppressors that allow cells to live in the absence of σE. We demonstrate that when σE is inhibited, cell envelope stress increases and envelope integrity is lost. Many cells lyse and some develop blebs containing cytoplasmic material along their sides. To better understand the connection: between transcription by σE and cell envelope integrity, we identified two multicopy suppressors of the essentiality of σ E, ptsN and yhbW. yhbW is a gene of unknown function, while ptsN is a member of the σE regulon. Overexpression of ptsN lowers the basal level of muttiple envelope stress responses, but not that of a cytoplasmic stress response. Our results are consistent with a model in which overexpression of ptsN reduces stress in the cell envelope, thereby promoting survival in the absence of σE.
AB - Extracytoplasmic function or ECF sigma factors are the most abundant class of alternative sigma factors in bacteria. Members of the rpoE subclass of ECF sigma factors are implicated in sensing stress in the cell envelope of Gram-negative bacteria and are required for virulence in many pathogens. The best-studied member of this family is rpoE from Escherichia coli, encoding the σE protein. σE has been well studied for its role in combating extracytoplasmic stress, and the members of its regulon have been largely defined. σE is required for viability of E coli, yet none of the studies to date explain why σE is essential in seemingly unstressed cells. In this work we investigate the essential role of σE in E coli by analyzing the phenotypes associated with loss of σE activity and isolating suppressors that allow cells to live in the absence of σE. We demonstrate that when σE is inhibited, cell envelope stress increases and envelope integrity is lost. Many cells lyse and some develop blebs containing cytoplasmic material along their sides. To better understand the connection: between transcription by σE and cell envelope integrity, we identified two multicopy suppressors of the essentiality of σ E, ptsN and yhbW. yhbW is a gene of unknown function, while ptsN is a member of the σE regulon. Overexpression of ptsN lowers the basal level of muttiple envelope stress responses, but not that of a cytoplasmic stress response. Our results are consistent with a model in which overexpression of ptsN reduces stress in the cell envelope, thereby promoting survival in the absence of σE.
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U2 - 10.1371/journal.pone.0001573
DO - 10.1371/journal.pone.0001573
M3 - Article
C2 - 18253509
AN - SCOPUS:45249100907
SN - 1932-6203
VL - 3
JO - PloS one
JF - PloS one
IS - 2
M1 - e1573
ER -