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Regulatory RNA as mediator in GacA/RsmA-dependent global control of exoproduct formation in Pseudomonas fluorescens CHA0.
- Source :
-
Journal of bacteriology [J Bacteriol] 2002 Feb; Vol. 184 (4), pp. 1046-56. - Publication Year :
- 2002
-
Abstract
- In Pseudomonas fluorescens CHA0, an antagonist of root-pathogenic fungi, the GacS/GacA two-component system tightly controls the expression of antifungal secondary metabolites and exoenzymes at a posttranscriptional level, involving the RNA-binding protein and global regulator of secondary metabolism RsmA. This protein was purified from P. fluorescens, and RNA bound to it was converted to cDNA, which served as a probe to isolate the corresponding chromosomal locus, rsmZ. This gene encoded a regulatory RNA of 127 nucleotides and a truncated form lacking 35 nucleotides at the 3' end. Expression of rsmZ depended on GacA, increased with increasing population density, and was stimulated by the addition of a solvent-extractable extracellular signal produced by strain CHA0 at the end of exponential growth. This signal appeared to be unrelated to N-acyl-homoserine lactones. A conserved upstream element in the rsmZ promoter, but not the stress sigma factor RpoS, was involved in rsmZ expression. Overexpression of rsmZ effectively suppressed the negative effect of gacS and gacA mutations on target genes, i.e., hcnA (for hydrogen cyanide synthase) and aprA (for the major exoprotease). Mutational inactivation of rsmZ resulted in reduced expression of these target genes in the presence of added signal. Overexpression of rsmA had a similar, albeit stronger negative effect. These results support a model in which GacA upregulates the expression of regulatory RNAs, such as RsmZ of strain CHA0, in response to a bacterial signal. By a titration effect, RsmZ may then alleviate the repressing activity of RsmA on the expression of target mRNAs.
- Subjects :
- 4-Butyrolactone metabolism
Amino Acid Sequence
Bacterial Proteins physiology
Base Sequence
Chromosome Mapping
Chromosomes, Bacterial
DNA, Bacterial
Exopeptidases genetics
Genes, Bacterial
Molecular Sequence Data
Multienzyme Complexes genetics
Mutagenesis
Nucleic Acid Conformation
Oxidoreductases genetics
Oxidoreductases Acting on CH-NH2 Group Donors
Pseudomonas fluorescens genetics
RNA-Binding Proteins genetics
RNA-Binding Proteins physiology
Regulatory Sequences, Nucleic Acid
Repressor Proteins genetics
Repressor Proteins physiology
Sigma Factor metabolism
Transcription Factors genetics
Transcription Factors metabolism
4-Butyrolactone analogs & derivatives
Bacterial Proteins genetics
Bacterial Proteins metabolism
Genes, Regulator
Pseudomonas fluorescens metabolism
RNA, Bacterial genetics
RNA-Binding Proteins metabolism
Repressor Proteins metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9193
- Volume :
- 184
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of bacteriology
- Publication Type :
- Academic Journal
- Accession number :
- 11807065
- Full Text :
- https://doi.org/10.1128/jb.184.4.1046-1056.2002