title: Identification of a pentatricopeptide repeat protein implicated in splicing of intron 1 of mitochondrial nad7 transcripts.
abstract: Splicing of plant organellar transcripts is facilitated by members of a large protein family, the pentatricopeptide repeat proteins. We have identified a pentatricopeptide repeat protein in a genetic screen for mutants resistant to inhibition of root growth by buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis and consequently named BIR6 (BSO-insensitive roots 6). BIR6 is involved in splicing of intron 1 of the mitochondrial nad7 transcript. Loss-of-function mutations in BIR6 result in a strongly reduced accumulation of fully processed nad7 transcript. This affects assembly of Complex I and results in moderate growth retardation. In agreement with disruption of Complex I function, the genes encoding alternative NADH oxidizing enzymes are induced in the mutant, and the mutant plants are less sensitive to mannitol and salt stress. Mutation in the BIR6 gene allowed normal root growth in presence of BSO and strongly attenuated depletion of glutathione content at these conditions. The same phenotype was observed with other mutants affected in function of Complex I, thus reinforcing the importance of Complex I function for cellular redox homeostasis.
authors.affiliation: Department of Metabolic Biology, John Innes Centre, Norwich NR4 7UH, United Kingdom.
authors.forename: Anna
authors.initials: A
authors.lastname: Koprivova
authors.forename: Catherine Colas
authors.initials: CC
authors.lastname: des Francs-Small
authors.forename: Grant
authors.initials: G
authors.lastname: Calder
authors.forename: Sam T
authors.initials: ST
authors.lastname: Mugford
authors.forename: Sandra
authors.initials: S
authors.lastname: Tanz
authors.forename: Bok-Rye
authors.initials: BR
authors.lastname: Lee
authors.forename: Bernd
authors.initials: B
authors.lastname: Zechmann
authors.forename: Ian
authors.initials: I
authors.lastname: Small
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kopriva
mesh_terms: D000963:Antimetabolites / Q000378:metabolism; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D019328:Buthionine Sulfoximine / Q000378:metabolism; D042967:Electron Transport Complex I / Q000378:metabolism; D017343:Genes, Plant; D005978:Glutathione / Q000235:genetics / Q000378:metabolism; D007438:Introns; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012326:RNA Splicing; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D000963:Antimetabolites; D029681:Arabidopsis Proteins; D011993:Recombinant Fusion Proteins; C538752:pentatricopeptide repeat protein, Arabidopsis; D019328:Buthionine Sulfoximine; D042967:Electron Transport Complex I; D005978:Glutathione