title: GiFRD encodes a protein involved in anaerobic growth in the arbuscular mycorrhizal fungus Glomus intraradices.
abstract: Fumarate reductase is a protein involved in the maintenance of redox balance during oxygen deficiency. This enzyme irreversibly catalyzes the reduction of fumarate to succinate and requires flavin cofactors as electron donors. Two examples are the soluble mitochondrial and the cytosolic fumarate reductases of Saccharomyces cerevisiae encoded by the OSM1 and FRDS1 genes, respectively. This work reports the identification and characterization of the gene encoding cytosolic fumarate reductase enzyme in the arbuscular mycorrhizal fungus, Glomus intraradices and the establishment of its physiological role. Using a yeast expression system, we demonstrate that G. intraradices GiFRD encodes a protein that has fumarate reductase activity which can functionally substitute for the S. cerevisiae fumarate reductases. Additionally, we showed that GiFRD transformants are not affected by presence of salt in medium, indicating that the presence of this gene has no effect on yeast behavior under osmotic stress. The fact that GiFRD expression and enzymatic activity was present only in asymbiotic stage confirmed existence of at least one anaerobic metabolic pathway in this phase of fungus life cycle. This suggests that the AMF behave as facultative anaerobes in the asymbiotic stage.
authors.affiliation: Leibniz Institute of Plant Genetics and Crop Plant Research, Corrensstr. 3, D-06466 Gatersleben, Germany.
authors.forename: Kinga A
authors.initials: KA
authors.lastname: Sędzielewska
authors.forename: Katja
authors.initials: K
authors.lastname: Vetter
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Bode
authors.forename: Keith
authors.initials: K
authors.lastname: Baronian
authors.forename: Roland
authors.initials: R
authors.lastname: Watzke
authors.forename: Gotthard
authors.initials: G
authors.lastname: Kunze
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis; D003600:Cytosol / Q000201:enzymology; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D018552:Daucus carota / Q000382:microbiology; D005650:Fumarates / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D055137:Glomeromycota / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D038821:Mycorrhizae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D010084:Oxidation-Reduction; D012331:RNA, Fungal / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D019802:Succinic Acid / Q000378:metabolism; D013559:Symbiosis
chemical_list: D004271:DNA, Fungal; D005650:Fumarates; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D019802:Succinic Acid; D013385:Succinate Dehydrogenase