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Role of the stress sigma factor RpoS in GacA/RsmA-controlled secondary metabolism and resistance to oxidative stress in Pseudomonas fluorescens CHA0.

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Title: Role of the stress sigma factor RpoS in GacA/RsmA-controlled secondary metabolism and resistance to oxidative stress in Pseudomonas fluorescens CHA0.
Authors: Heeb, S., Valverde, C., Gigot-Bonnefoy, C., Haas, D.
Publication Year: 2025
Collection: Université de Lausanne (UNIL): Serval - Serveur académique lausannois
Subject Terms: Bacterial Proteins/genetics, Bacterial Proteins/metabolism, Exopeptidases/genetics, Exopeptidases/metabolism, Gene Expression Regulation, Bacterial, Hydrogen Peroxide/pharmacology, Multienzyme Complexes/genetics, Multienzyme Complexes/metabolism, Oxidative Stress, Oxidoreductases/genetics, Oxidoreductases/metabolism, Oxidoreductases Acting on CH-NH2 Group Donors, Pseudomonas fluorescens/genetics, Pseudomonas fluorescens/growth & development, RNA-Binding Proteins/genetics, RNA-Binding Proteins/metabolism, Repressor Proteins/genetics, Repressor Proteins/metabolism, Sigma Factor/genetics, Sigma Factor/metabolism, Signal Transduction
Description: In Pseudomonas fluorescens biocontrol strain CHA0, the two-component system GacS/GacA positively controls the synthesis of extracellular products such as hydrogen cyanide, protease, and 2,4-diacetylphloroglucinol, by upregulating the transcription of small regulatory RNAs which relieve RsmA-mediated translational repression of target genes. The expression of the stress sigma factor sigmaS (RpoS) was controlled positively by GacA and negatively by RsmA. By comparison with the wild-type CHA0, both a gacS and an rpoS null mutant were more sensitive to H2O2 in stationary phase. Overexpression of rpoS or of rsmZ, encoding a small RNA antagonistic to RsmA, restored peroxide resistance to a gacS mutant. By contrast, the rpoS mutant showed a slight increase in the expression of the hcnA (HCN synthase subunit) gene and of the aprA (major exoprotease) gene, whereas overexpression of sigmaS strongly reduced the expression of these genes. These results suggest that in strain CHA0, regulation of exoproduct synthesis does not involve sigmaS as an intermediate in the Gac/Rsm signal transduction pathway whereas sigmaS participates in Gac/Rsm-mediated resistance to oxidative stress.
Document Type: article in journal/newspaper
File Description: application/pdf
Language: English
Relation: FEMS Microbiology Letters; 0378-1097[print], 0378-1097[linking]; https://iris.unil.ch/handle/iris/63585; serval:BIB_128308AA67F4; 000226875000034
DOI: 10.1016/j.femsle.2004.12.008
Availability: https://iris.unil.ch/handle/iris/63585
https://doi.org/10.1016/j.femsle.2004.12.008
Accession Number: edsbas.8183E306
Database: BASE
Description
Abstract:In Pseudomonas fluorescens biocontrol strain CHA0, the two-component system GacS/GacA positively controls the synthesis of extracellular products such as hydrogen cyanide, protease, and 2,4-diacetylphloroglucinol, by upregulating the transcription of small regulatory RNAs which relieve RsmA-mediated translational repression of target genes. The expression of the stress sigma factor sigmaS (RpoS) was controlled positively by GacA and negatively by RsmA. By comparison with the wild-type CHA0, both a gacS and an rpoS null mutant were more sensitive to H2O2 in stationary phase. Overexpression of rpoS or of rsmZ, encoding a small RNA antagonistic to RsmA, restored peroxide resistance to a gacS mutant. By contrast, the rpoS mutant showed a slight increase in the expression of the hcnA (HCN synthase subunit) gene and of the aprA (major exoprotease) gene, whereas overexpression of sigmaS strongly reduced the expression of these genes. These results suggest that in strain CHA0, regulation of exoproduct synthesis does not involve sigmaS as an intermediate in the Gac/Rsm signal transduction pathway whereas sigmaS participates in Gac/Rsm-mediated resistance to oxidative stress.
DOI:10.1016/j.femsle.2004.12.008