title: Regulation of fixLJ by Hfq Controls Symbiotically Important Genes in Sinorhizobium meliloti.
abstract: The RNA-binding chaperone Hfq plays critical roles in the establishment and functionality of the symbiosis between Sinorhizobium meliloti and its legume hosts. A mutation in hfq reduces symbiotic efficiency resulting in a Fix-phenotype, characterized by the inability of the bacterium to fix nitrogen. At least in part, this is due to the ability of Hfq to regulate the fixLJ operon, which encodes a sensor kinase-response regulator pair that controls expression of the nitrogenase genes. The ability of Hfq to bind fixLJ in vitro and in planta was demonstrated with gel shift and coimmunoprecipitation experiments. Two (ARN)2motifs in the fixLJ message were the likely sites through which Hfq exerted its posttranscriptional control. Consistent with the regulatory effects of Hfq, downstream genes controlled by FixLJ (such as nifK, noeB) were also subject to Hfq regulation in planta.
authors.affiliation: Soil and Water Sciences Department, Genetics Institute, University of Florida-Institute of Food and Agricultural Sciences, Gainesville 32611, U.S.A.
authors.forename: Mengsheng
authors.initials: M
authors.lastname: Gao
authors.affiliation: Soil and Water Sciences Department, Genetics Institute, University of Florida-Institute of Food and Agricultural Sciences, Gainesville 32611, U.S.A.
authors.forename: Hahn
authors.initials: H
authors.lastname: Nguyen
authors.affiliation: Soil and Water Sciences Department, Genetics Institute, University of Florida-Institute of Food and Agricultural Sciences, Gainesville 32611, U.S.A.
authors.forename: Isai
authors.initials: I
authors.lastname: Salas González
authors.affiliation: Soil and Water Sciences Department, Genetics Institute, University of Florida-Institute of Food and Agricultural Sciences, Gainesville 32611, U.S.A.
authors.forename: Max
authors.initials: M
authors.lastname: Teplitski
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D015964:Gene Expression Regulation, Bacterial; D006420:Hemeproteins / Q000235:genetics / Q000378:metabolism*; D000071677:Histidine Kinase; D035001:Host Factor 1 Protein / Q000235:genetics / Q000378:metabolism*; D046913:Medicago truncatula / Q000382:microbiology*; D009154:Mutation; D009876:Operon / Q000235:genetics; D010641:Phenotype; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000382:microbiology; D016962:Sinorhizobium meliloti / Q000235:genetics* / Q000502:physiology; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D006420:Hemeproteins; D035001:Host Factor 1 Protein; D012329:RNA, Bacterial; D012333:RNA, Messenger; C069289:FixJ protein, Bacteria; C067929:FixL protein, Bacteria; D000071677:Histidine Kinase