title: Proteomic alterations explain phenotypic changes in Sinorhizobium meliloti lacking the RNA chaperone Hfq.
abstract: The ubiquitous bacterial RNA-binding protein Hfq is involved in stress resistance and pathogenicity. In Sinorhizobium meliloti, Hfq is essential for the establishment of symbiosis with Medicago sativa and for nitrogen fixation. A proteomic analysis identifies 55 proteins with significantly affected expression in the hfq mutant; most of them are involved in cell metabolism or stress resistance. Important determinants of oxidative stress resistance, such as CysK, Gsh, Bfr, SodC, KatB, KatC, and a putative peroxiredoxine (SMc00072), are downregulated in the hfq mutant. The hfq mutant is affected for H(2)O(2), menadione, and heat stress resistance. Part of these defects could result from the reductions of rpoE1, rpoE2, rpoE3, and rpoE4 expression levels in the hfq mutant. Some proteins required for efficient symbiosis are reduced in the hfq mutant, contributing to the drastic defect in nodulation observed in this mutant.
authors.affiliation: Interactions Cellulaires et Moleculaires, DUALS, CNRS UMR 6026, Université de Rennes I, Campus de Beaulieu, 35042 Rennes Cedex, France.
authors.forename: Lise
authors.initials: L
authors.lastname: Barra-Bily
authors.forename: Catherine
authors.initials: C
authors.lastname: Fontenelle
authors.forename: Gwenael
authors.initials: G
authors.lastname: Jan
authors.forename: Maud
authors.initials: M
authors.lastname: Flechard
authors.forename: Annie
authors.initials: A
authors.lastname: Trautwetter
authors.forename: Shree P
authors.initials: SP
authors.lastname: Pandey
authors.forename: Graham C
authors.initials: GC
authors.lastname: Walker
authors.forename: Carlos
authors.initials: C
authors.lastname: Blanco
mesh_terms: D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D035001:Host Factor 1 Protein / Q000235:genetics* / Q000378:metabolism*; D000455:Medicago sativa / Q000382:microbiology; D009154:Mutation; D010641:Phenotype; D040901:Proteomics; D016962:Sinorhizobium meliloti / Q000235:genetics* / Q000378:metabolism*; D013559:Symbiosis
chemical_list: D035001:Host Factor 1 Protein