title: Respiratory complex I deficiency results in low nitric oxide levels, induction of hemoglobin and upregulation of fermentation pathways.
abstract: The cytoplasmic male-sterile (CMS) mutant of Nicotiana sylvestris which lacks NAD7, one of the subunits of respiratory complex I (NADH: ubiquinone oxidoreductase, EC 1.6.5.3), is characterized by very low (~10 times lower as compared to the wild type plants) emissions of nitric oxide (NO) under hypoxic conditions. The level of the non-symbiotic class 1 hemoglobin, as shown by Western blotting, is increased compared to the wild type plants not only under hypoxia but this protein reveals its marked expression in the CMS mutant even under normoxic conditions. The activity of aconitase (EC 4.2.1.3) is low in the CMS mutant, especially in the mitochondrial compartment, which indicates the suppression of the tricarboxylic acid cycle. The CMS mutant exhibits the severalfold higher activities of alcohol dehydrogenase (EC 1.1.1.1) and lactate dehydrogenase (EC 1.1.1.27) under the normoxic conditions as compared to the wild type plants. It is concluded that the lack of functional complex I results in upregulation of the pathways of hypoxic metabolism which include both fermentation of pyruvate and scavenging of NO by the non-symbiotic hemoglobin.
authors.affiliation: Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada.
authors.forename: Jay K
authors.initials: JK
authors.lastname: Shah
authors.forename: Devin W
authors.initials: DW
authors.lastname: Cochrane
authors.forename: Rosine
authors.initials: R
authors.lastname: De Paepe
authors.forename: Abir U
authors.initials: AU
authors.lastname: Igamberdiev
mesh_terms: D000154:Aconitate Hydratase / Q000378:metabolism; D042967:Electron Transport Complex I / Q000172:deficiency* / Q000378:metabolism*; D005285:Fermentation; D018506:Gene Expression Regulation, Plant; D006454:Hemoglobins / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D014026:Nicotiana / Q000378:metabolism*
chemical_list: D006454:Hemoglobins; D010940:Plant Proteins; D009569:Nitric Oxide; D000154:Aconitate Hydratase; D042967:Electron Transport Complex I