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New envelope stress factors involved in σE activation and conditional lethality of rpoE mutations in Salmonella enterica.
Microbiology (Reading). 2018 10; 164(10):1293-1307.M

Abstract

Salmonella enterica serovar Typhimurium (S. typhimurium) can cause food- and water-borne illness with diverse clinical manifestations. One key factor for S. typhimurium pathogenesis is the alternative sigma factor σE, which is encoded by the rpoE gene and controls the transcription of genes required for outer-membrane integrity in response to alterations in the bacterial envelope. The canonical pathway for σE activation involves proteolysis of the antisigma factor RseA, which is triggered by unfolded outer-membrane porins (OMPs) and lipopolysaccharides (LPS) that have accumulated in the periplasm. This study reports new stress factors that are able to activate σE expression. We demonstrate that UVA radiation induces σE activity in a pathway that is dependent on the stringent response regulator ppGpp. Survival assays revealed that rpoE has a role in the defence against lethal UVA doses that is mediated by functions that are dependent on and independent of the alternative sigma factor RpoS. We also report that the envelope stress generated by phage infection requires a functional rpoE gene for optimal bacterial tolerance and that it is able to induce σE activity in an RseA-dependent fashion. σE activity is also induced by hypo-osmotic shock in the absence of osmoregulated periplasmic glucans (OPGs). It is known that the rpoE gene is not essential in S. typhimurium. However, we report here two cases of the conditional lethality of rpoE mutations in this micro-organism. We demonstrate that rpoE mutations are not tolerated in the absence of OPGs (at low to moderate osmolarity) or LPS O-antigen. The latter case resembles that of the prototypic Escherichia coli strain K12, which neither synthesizes a complete LPS nor tolerates null rpoE mutations.

Authors+Show Affiliations

Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina.Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina.Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina.Dpto. de Radiobiología, Comisión Nacional de Energía Atómica, General San Martín, Argentina.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

30084765

Citation

Amar, Agustina, et al. "New Envelope Stress Factors Involved in σE Activation and Conditional Lethality of rpoE Mutations in Salmonella Enterica." Microbiology (Reading, England), vol. 164, no. 10, 2018, pp. 1293-1307.
Amar A, Pezzoni M, Pizarro RA, et al. New envelope stress factors involved in σE activation and conditional lethality of rpoE mutations in Salmonella enterica. Microbiology (Reading). 2018;164(10):1293-1307.
Amar, A., Pezzoni, M., Pizarro, R. A., & Costa, C. S. (2018). New envelope stress factors involved in σE activation and conditional lethality of rpoE mutations in Salmonella enterica. Microbiology (Reading, England), 164(10), 1293-1307. https://doi.org/10.1099/mic.0.000701
Amar A, et al. New Envelope Stress Factors Involved in σE Activation and Conditional Lethality of rpoE Mutations in Salmonella Enterica. Microbiology (Reading). 2018;164(10):1293-1307. PubMed PMID: 30084765.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - New envelope stress factors involved in σE activation and conditional lethality of rpoE mutations in Salmonella enterica. AU - Amar,Agustina, AU - Pezzoni,Magdalena, AU - Pizarro,Ramón A, AU - Costa,Cristina S, Y1 - 2018/08/06/ PY - 2018/8/8/pubmed PY - 2019/9/20/medline PY - 2018/8/8/entrez KW - Salmonella enterica KW - alternative sigma factor σE KW - envelope stress KW - rpoE SP - 1293 EP - 1307 JF - Microbiology (Reading, England) JO - Microbiology (Reading) VL - 164 IS - 10 N2 - Salmonella enterica serovar Typhimurium (S. typhimurium) can cause food- and water-borne illness with diverse clinical manifestations. One key factor for S. typhimurium pathogenesis is the alternative sigma factor σE, which is encoded by the rpoE gene and controls the transcription of genes required for outer-membrane integrity in response to alterations in the bacterial envelope. The canonical pathway for σE activation involves proteolysis of the antisigma factor RseA, which is triggered by unfolded outer-membrane porins (OMPs) and lipopolysaccharides (LPS) that have accumulated in the periplasm. This study reports new stress factors that are able to activate σE expression. We demonstrate that UVA radiation induces σE activity in a pathway that is dependent on the stringent response regulator ppGpp. Survival assays revealed that rpoE has a role in the defence against lethal UVA doses that is mediated by functions that are dependent on and independent of the alternative sigma factor RpoS. We also report that the envelope stress generated by phage infection requires a functional rpoE gene for optimal bacterial tolerance and that it is able to induce σE activity in an RseA-dependent fashion. σE activity is also induced by hypo-osmotic shock in the absence of osmoregulated periplasmic glucans (OPGs). It is known that the rpoE gene is not essential in S. typhimurium. However, we report here two cases of the conditional lethality of rpoE mutations in this micro-organism. We demonstrate that rpoE mutations are not tolerated in the absence of OPGs (at low to moderate osmolarity) or LPS O-antigen. The latter case resembles that of the prototypic Escherichia coli strain K12, which neither synthesizes a complete LPS nor tolerates null rpoE mutations. SN - 1465-2080 UR - https://www.unboundmedicine.com/medline/citation/30084765/New_envelope_stress_factors_involved_in_σE_activation_and_conditional_lethality_of_rpoE_mutations_in_Salmonella_enterica_ L2 - http://mic.microbiologyresearch.org/pubmed/content/journal/micro/10.1099/mic.0.000701 DB - PRIME DP - Unbound Medicine ER -