title: Effect of phosphoglycerate mutase and fructose 1,6-bisphosphatase deficiency on symbiotic Burkholderia phymatum.
abstract: Burkholderia phymatum STM815 is a β-rhizobial strain that can effectively nodulate several species of the large legume genus Mimosa. Two Tn5-induced mutants of this strain, KM16-22 and KM51, failed to form root nodules on Mimosa pudica, but still caused root hair deformation, which is one of the early steps of rhizobial infection. Both mutants grew well in a complex medium. However, KM16-22 could not grow on minimal medium unless a sugar and a metabolic intermediate such as pyruvate were provided, and KM51 also could not grow on minimal medium unless a sugar was added. The Tn5-interrupted genes of the mutants showed strong homologies to pgm, which encodes 2,3-biphosphoglycerate-dependent phosphoglycerate mutase (dPGM), and fbp, which encodes fructose 1,6-bisphosphatase (FBPase). Both enzymes are known to be involved in obligate steps in carbohydrate metabolism. Enzyme assays confirmed that KM16-22 and KM51 had indeed lost dPGM and FBPase activity, respectively, whilst the activities of these enzymes were expressed normally in both free-living bacteria and symbiotic bacteroids of the parental strain STM815. Both mutants recovered their enzyme activity after the introduction of wild-type pgm or fbp genes, were subsequently able to use carbohydrate as a carbon source, and were able to form root nodules on M. pudica and to fix nitrogen as efficiently as the parental strain. We conclude that the enzymes dPGM and FBPase are essential for the formation of a symbiosis with the host plant.
authors.affiliation: Laboratory of Microbiology, Department of Seafood Science, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC.
authors.forename: Wen-Ming
authors.initials: WM
authors.lastname: Chen
authors.affiliation: Soil Ecology, Department of Botany, RWTH Aachen, 52056 Aachen, Germany.
authors.forename: Jurgen
authors.initials: J
authors.lastname: Prell
authors.affiliation: The James Hutton Institute, Invergowrie, Dundee DD2 5DA, UK.
authors.forename: Euan K
authors.initials: EK
authors.lastname: James
authors.affiliation: Department of Marine Biotechnology, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC.
authors.forename: Der-Shyan
authors.initials: DS
authors.lastname: Sheu
authors.affiliation: Department of Marine Biotechnology, National Kaohsiung Marine University, No. 142, Hai-Chuan Rd, Nan-Tzu, Kaohsiung City 811, Taiwan, ROC.
authors.forename: Shih-Yi
authors.initials: SY
authors.lastname: Sheu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019117:Burkholderia / Q000201:enzymology* / Q000235:genetics; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D006597:Fructose-Bisphosphatase / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D031298:Mimosa / Q000382:microbiology*; D016296:Mutagenesis; D009586:Nitrogen Fixation; D010736:Phosphoglycerate Mutase / Q000235:genetics / Q000378:metabolism*; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000382:microbiology; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D006597:Fructose-Bisphosphatase; D010736:Phosphoglycerate Mutase