title: A single mutation in the oprF mRNA leader confers strict translational control by the Gac/Rsm system in Pseudomonas fluorescens CHA0.
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.
authors.affiliation: Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Argentina.
authors.forename: María Cecilia Alvarez
authors.initials: MC
authors.lastname: Crespo
authors.forename: Claudio
authors.initials: C
authors.lastname: Valverde
mesh_terms: D020121:5' Untranslated Regions; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017354:Point Mutation; D014176:Protein Biosynthesis; D011551:Pseudomonas fluorescens / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D022661:RNA, Untranslated / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D012333:RNA, Messenger; D022661:RNA, Untranslated