PubAg

Main content area

A Single Mutation in the oprF mRNA Leader Confers Strict Translational Control by the Gac/Rsm System in Pseudomonas fluorescens CHA0

Author:
Alvarez Crespo, María Cecilia, Valverde, Claudio
Source:
Current microbiology 2009 v.58 no.2 pp. 182-188
ISSN:
0343-8651
Subject:
Pseudomonas fluorescens, crops, cucumbers, cultivars, messenger RNA, mutants, mutation, nucleotide sequences, plant pathogenic fungi, porins, roots, secondary metabolites, tomatoes
Abstract:
The rhizobacterium Pseudomonas fluorescens CHA0 is able to antagonize fungal phytopathogens on a variety of crop plants, mainly due to the production of secondary metabolites that are coordinately upregulated by the global regulatory Gac/Rsm cascade. The two-component system GacS/GacA activates transcription of the three small regulatory RNAs RsmX, RsmY, and RsmZ, which counteract translational repression of target mRNAs by RsmA and RsmE proteins. In a search for novel Gac/Rsm targets based on the minimal sequence on mRNA leaders required for RsmA/RsmE control, the leader region of the major porin OprF emerged as a candidate. Although an isogenic CHA0 oprF mutant showed a reduced ability to attach to cucumber and tomato roots, suggesting a role for OprF in root colonization as a requisite for pathogen antagonism, a translational oprF'-'lacZ fusion was weakly regulated by Gac/Rsm despite its high sequence similarity to the hcnA leader. A single base substitution put the modified oprF 5'-UTR under strict control by Gac/Rsm. The results highlight the subtle sequence requirements of Gac/Rsm targets.
Agid:
634647