title: Role of the Sinorhizobium meliloti global regulator Hfq in gene regulation and symbiosis.
abstract: The RNA-binding protein Hfq is a global regulator which controls diverse cellular processes in bacteria. To begin understanding the role of Hfq in the Sinorhizobium meliloti-Medicago truncatula nitrogen-fixing symbiosis, we defined free-living and symbiotic phenotypes of an hfq mutant. Over 500 transcripts were differentially accumulated in the hfq mutant of S. meliloti Rm1021 when grown in a shaking culture. Consistent with transcriptome-wide changes, the hfq mutant displayed dramatic alterations in metabolism of nitrogen-containing compounds, even though its carbon source utilization profiles were nearly identical to the wild type. The hfq mutant had reduced motility and was impaired for growth at alkaline pH. A deletion of hfq resulted in a reduced symbiotic efficiency, although the mutant was still able to initiate nodule development and differentiate into bacteroids.
authors.affiliation: Soil and Water Science Department, Cancer and Genetics Research Complex, Room 330E, University of Florida-Institute of Food and Agricultural Sciences, Gainesville 32610, U.S.A.
authors.forename: Mengsheng
authors.initials: M
authors.lastname: Gao
authors.affiliation: Department of Biology, Stanford University, Stanford, CA 94305-5020, U.S.A.
authors.forename: Melanie J
authors.initials: MJ
authors.lastname: Barnett
authors.affiliation: Department of Biology, Stanford University, Stanford, CA 94305-5020, U.S.A.
authors.forename: Sharon R
authors.initials: SR
authors.lastname: Long
authors.affiliation: Soil and Water Science Department, Cancer and Genetics Research Complex, Room 330E, University of Florida-Institute of Food and Agricultural Sciences, Gainesville 32610, U.S.A.
authors.forename: Max
authors.initials: M
authors.lastname: Teplitski
mesh_terms: D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D035001:Host Factor 1 Protein / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D046913:Medicago truncatula / Q000382:microbiology / Q000502:physiology; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000382:microbiology / Q000648:ultrastructure; D016962:Sinorhizobium meliloti / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D013559:Symbiosis / Q000235:genetics / Q000502:physiology*
chemical_list: D035001:Host Factor 1 Protein