RESUMEN
The plant mitochondrial DNA-binding protein ODB1 was identified from a mitochondrial extract after DNA-affinity purification. ODB1 (organellar DNA-binding protein 1) co-purified with WHY2, a mitochondrial member of the WHIRLY family of plant-specific proteins involved in the repair of organellar DNA. The Arabidopsis thaliana ODB1 gene is identical to RAD52-1, which encodes a protein functioning in homologous recombination in the nucleus but additionally localizing to mitochondria. We confirmed the mitochondrial localization of ODB1 by in vitro and in vivo import assays, as well as by immunodetection on Arabidopsis subcellular fractions. In mitochondria, WHY2 and ODB1 were found in large nucleo-protein complexes. Both proteins co-immunoprecipitated in a DNA-dependent manner. In vitro assays confirmed DNA binding by ODB1 and showed that the protein has higher affinity for single-stranded than for double-stranded DNA. ODB1 showed no sequence specificity in vitro. In vivo, DNA co-immunoprecipitation indicated that ODB1 binds sequences throughout the mitochondrial genome. ODB1 promoted annealing of complementary DNA sequences, suggesting a RAD52-like function as a recombination mediator. Arabidopsis odb1 mutants were morphologically indistinguishable from the wild-type, but following DNA damage by genotoxic stress, they showed reduced mitochondrial homologous recombination activity. Under the same conditions, the odb1 mutants showed an increase in illegitimate repair bypasses generated by microhomology-mediated recombination. These observations identify ODB1 as a further component of homologous recombination-dependent DNA repair in plant mitochondria.
Asunto(s)
Arabidopsis/genética , Brassica/genética , Reparación del ADN , ADN Mitocondrial/genética , Proteínas de Unión al ADN/metabolismo , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Brassica/metabolismo , Cromatografía de Afinidad , Roturas del ADN de Doble Cadena , Daño del ADN , ADN de Plantas/genética , Proteínas de Unión al ADN/genética , Flores/genética , Flores/metabolismo , Recombinación Homóloga , Mitocondrias/genética , Mitocondrias/metabolismo , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Mutación , Especificidad de Órganos , Hojas de la Planta/genética , Hojas de la Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raíces de Plantas/genética , Raíces de Plantas/metabolismo , Plantas Modificadas Genéticamente , Proteína Recombinante y Reparadora de ADN Rad52/genética , Proteína Recombinante y Reparadora de ADN Rad52/metabolismo , Plantones/genética , Plantones/metabolismoRESUMEN
The mRNAs of the nad6 and ccmC genes of Arabidopsis and cauliflower were found to be processed upstream of the inframe stop codons. This result was confirmed by northern hybridization and by RT-PCR. There is no evidence that an alternative stop codon is created post-transcriptionally, either by RNA editing or by polyadenylation. The non-stop mRNAs are found in the high molecular weight polysomal fractions, suggesting that they are translated. Using antibodies directed against CcmC, the corresponding protein was detected in Arabidopsis mitochondrial extracts. These observations raise the question of how the plant mitochondrial translation system deals with non-stop mRNAs.
Asunto(s)
Arabidopsis/genética , Brassica/genética , Codón de Terminación/genética , Proteínas Mitocondriales/genética , Proteínas de Plantas/genética , Arabidopsis/metabolismo , Secuencia de Bases , Brassica/metabolismo , Línea Celular , Regulación de la Expresión Génica de las Plantas , Proteínas Mitocondriales/metabolismo , Datos de Secuencia Molecular , Proteínas de Plantas/metabolismo , Transcripción GenéticaRESUMEN
The 14-3-3 proteins are a family of highly conserved proteins found in all eukaryotes - from the yeasts to mammals. They regulate several cellular processes recognizing unique conservative, mostly phosphorylated motif of partner proteins. Binding of the 14-3-3 proteins regulates their partners through a variety of mechanisms, such as altering their catalytic activity, subcellular localization, stability or altering their interactions with other protein molecules. The native 14-3-3 proteins are present in form of homo- and hetero-dimers. The most structurally variable N-and C-termini are responsible for isoform specific protein-protein interactions, and cellular localization. In plant cell, 14-3-3 proteins appear to play an important role in regulation of key enzymes of carbon and nitrogen metabolism, modulation ion pumps and channels. They are also involved in signal transduction pathways and even in gene expression.
Asunto(s)
Proteínas 14-3-3/metabolismo , Proteínas de Plantas/metabolismo , Proteínas Adaptadoras Transductoras de Señales , Núcleo Celular/metabolismo , Regulación de la Expresión Génica de las Plantas/fisiología , Modelos Biológicos , Chaperonas Moleculares , Plantas , Unión Proteica/fisiología , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Transducción de Señal/fisiologíaRESUMEN
Three copies of the PSST gene were identified in the lupine genomic root library, however, only two transcripts were found in the lupine root cDNA library. The transcript of the third PSST gene was identified in RNA from lupine flowers. The genes are 92% identical in the coding region, while the 5' parts of the reading frames specifying the N-terminal presequences for mitochondrial import show about 87% sequence identity. The differences between genes concern mostly the third nucleotide of the codons and the length of the intron. Transcripts of three PSST genes differ in abundance in flowers and leaves.
Asunto(s)
Fabaceae/genética , Genes de Plantas , NADH Deshidrogenasa/genética , Secuencia de Aminoácidos , Transporte de Electrón , Complejo I de Transporte de Electrón , Fabaceae/enzimología , Fabaceae/metabolismo , Dosificación de Gen , Sustancias Macromoleculares , Datos de Secuencia Molecular , NADH Deshidrogenasa/biosíntesis , NADH NADPH Oxidorreductasas/química , Subunidades de Proteína , ARN de Planta/biosíntesis , Alineación de SecuenciaRESUMEN
PPR proteins belong to large family of nucleic acid binding proteins, mainly RNA-binding proteins. Their name is defined by the presence of so-called pentatricopeptide repeat (PPR), a degenerate 35-aminoacid repeats containing from 2 up to 26 such motifs arrayed in tandem of at least in one pair. PPR motif consists of two a helices A and B forming a superhelix enclosing a groove or tunnel which is likely to be the ligand-binding site. PPR proteins are targeted mainly to mitochondria and chloroplasts where they are mainly involved in posttranscriptional processes and translation. Among PPR proteins they were also found restorer gene products which restorer pollen fertility. Some PPR proteins play roles as adaptors and partner in protein-protein interaction. PPR protein genes were discovered in all analyzed eukariotic genomes. They are especially abundant in plants.
Asunto(s)
Proteínas de Plantas/metabolismo , Proteínas de Unión al ARN/metabolismo , Sitios de Unión , Cloroplastos/metabolismo , Expresión Génica , Ligandos , Mitocondrias/metabolismo , Polen/metabolismo , Biosíntesis de Proteínas , Procesamiento Postranscripcional del ARN , Secuencias Repetitivas de AminoácidoRESUMEN
The mitochondrial nad9 and nad6 genes were analyzed in four lupin species: Lupinus luteus, Lupinus angustifolius, Lupinus albus and Lupinus mutabilis. The nucleotide sequence of these genes confirmed their high conservation, however, higher number of nucleotide substitution was observed in the L. albus genes. Southern hybridizations confirmed the presence of single copy number of these genes in L. luteus, L. albus and L. angustifolius. The expression of nad9 and nad6 genes was analyzed by Northern in different tissue types of analyzed lupin species. Transcription analyses of the two nad genes displayed single predominant mRNA species of about 0.6 kb in L. luteus and L. angustifolius. The L. albus transcripts were larger in size. The nad9 and nad6 transcripts were modified by RNA editing at 8 and 11 positions, in L. luteus and L. angustifolius, respectively. The gene order, rps3-rpl16-nad9, found in Arabidopsis thaliana is also conserved in L. luteus and L. angustifolius mitochondria. L. luteus and L. angustifolius showed some variability in the sequence of the nad9 promoter region. The last feature along with the differences observed in nad9 mRNA 5' termini of two lupins differentiate L. luteus and L. angustifolius species.
Asunto(s)
Regiones no Traducidas 5'/genética , Lupinus/genética , NADH Deshidrogenasa/genética , Secuencia de Bases , Northern Blotting , ADN Complementario/química , ADN Complementario/genética , ADN Mitocondrial/química , ADN Mitocondrial/genética , ADN de Plantas/química , ADN de Plantas/genética , Regulación Enzimológica de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Orden Génico , Lupinus/enzimología , Datos de Secuencia Molecular , Subunidades de Proteína/genética , ARN/genética , ARN/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Mitocondrial , Análisis de Secuencia de ADN , Especificidad de la EspecieRESUMEN
Ninety-one potato genotypes (cultivars and breeding lines) selected as resistant or susceptible to pathotype Ro1 of Globodera rostochiensis were screened for the presence of two PCR markers, 0.14 and 0.76 kb in length. Both PCR markers were linked with the H1 gene, located at the distal end of the long arm of chromosome V, and were present in 88 to 100% of the resistant cultivars and breeding lines. The 0.76 kb PCR marker was detected in all resistant genotypes and in approximately 86% of susceptible breeding lines as well as in all susceptible cultivars. The 0.14 kb marker was detected in 88% of resistant breeding lines and in 94% of resistant cultivars. Most of the susceptible genotypes tested (91% of cultivars, but only 50% of breeding lines) did not show the presence of the 0.14 kb marker. We conclude that the 0.14 kb H1 marker is likely to be useful for the proper selection of potato genotypes resistant to the Ro1 pathotype of G. rostochiensis.