title: Rhizobium leguminosarum methyl-accepting chemotaxis protein genes are down-regulated in the pea nodule.
abstract: Regulation of methyl-accepting chemotaxis protein (MCP) genes of Rhizobium leguminosarum was studied under symbiotic conditions. Transcriptional fusions using both beta-galactosidase and beta-glucuronidase genes within two different mcp genes demonstrated that mcp expression decreased significantly during nodulation. Immunoblots using an anti-MCP antibody detected MCPs in free-living cells but not in bacteroids. Down-regulation during nodulation was not dependent upon known regulatory proteins involved in induction of expression of genes involved in nitrogen fixation. Environmental conditions found in the bacteroid that may trigger down-regulation were investigated by growing free-living cultures under a variety of growth conditions. Growth under low oxygen concentration or using succinate as a sole carbon source did not lower expression of the mcp gene fusions.
authors.affiliation: Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Yost
authors.forename: Kate L
authors.initials: KL
authors.lastname: Del Bel
authors.forename: Jürgen
authors.initials: J
authors.lastname: Quandt
authors.forename: Michael F
authors.initials: MF
authors.lastname: Hynes
mesh_terms: D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D015153:Blotting, Western; D015536:Down-Regulation; D015964:Gene Expression Regulation, Bacterial; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D000072236:Methyl-Accepting Chemotaxis Proteins; D009586:Nitrogen Fixation / Q000235:genetics; D010100:Oxygen / Q000378:metabolism; D018532:Pisum sativum / Q000382:microbiology*; D016961:Rhizobium leguminosarum / Q000235:genetics* / Q000502:physiology; D013386:Succinates / Q000378:metabolism; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D013386:Succinates; D010100:Oxygen