title: Light inhibition of fumarase in Arabidopsis leaves is phytochrome A-dependent and mediated by calcium.
abstract: Inhibition of fumarase activity in the light has been studied in Arabidopsis in relation to the involvement of phytochrome. Using knockout phytochrome mutants, we observed that the main regulator of FUM1 gene transcription, encoding the mitochondrial form of fumarase, is phytochrome A. The active form of phytochrome A suppressed FUM1 expression, while the expression of the FUM2 gene encoding the cytosolic form of fumarase was unaffected both in darkness and in light. The nuclear concentration of Ca(2+) was modulated by red and far-red light. We suggest that the signal transduction mechanism operates via Ca(2+) activation of expression of the gene encoding the transcription factor PIF3, which binds to promoters of phytochrome-regulated genes and inhibits FUM1 expression.
authors.affiliation: Department of Biochemistry and Cell Physiology, Voronezh State University, 394006 Voronezh, Russia.
authors.forename: Alexander T
authors.initials: AT
authors.lastname: Eprintsev
authors.affiliation: Department of Biochemistry and Cell Physiology, Voronezh State University, 394006 Voronezh, Russia.
authors.forename: Dmitry N
authors.initials: DN
authors.lastname: Fedorin
authors.affiliation: Department of Biochemistry and Cell Physiology, Voronezh State University, 394006 Voronezh, Russia.
authors.forename: Oksana V
authors.initials: OV
authors.lastname: Sazonova
authors.affiliation: Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada. Electronic address: igamberdiev@mun.ca.
authors.forename: Abir U
authors.initials: AU
authors.lastname: Igamberdiev
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000235:genetics; D002118:Calcium / Q000494:pharmacology*; D005649:Fumarate Hydratase / Q000096:biosynthesis* / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000528:radiation effects; D008027:Light; D051942:Phytochrome A / Q000096:biosynthesis* / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D051942:Phytochrome A; D005649:Fumarate Hydratase; D002118:Calcium
keywords: Arabidopsis; Ca(2+); Fumarase; Mitochondria; Phytochrome; Respiration