RESUMEN
Mono- and multi-ubiquitination alters the functions and subcellular localization of many cellular and viral proteins. Viruses can co-opt or actively manipulate the ubiquitin network to support viral processes or suppress innate immunity. Using yeast (Saccharomyces cerevisiae) model host, we show that the yeast Rad6p (radiation sensitive 6) E2 ubiquitin-conjugating enzyme and its plant ortholog, AtUbc2, interact with two tombusviral replication proteins and these E2 ubiquitin-conjugating enzymes could be co-purified with the tombusvirus replicase. We demonstrate that TBSV RNA replication and the mono- and bi-ubiquitination level of p33 is decreased in rad6Δ yeast. However, plasmid-based expression of AtUbc2p could complement both defects in rad6Δ yeast. Knockdown of UBC2 expression in plants also decreases tombusvirus accumulation and reduces symptom severity, suggesting that Ubc2p is critical for virus replication in plants. We provide evidence that Rad6p is involved in promoting the subversion of Vps23p and Vps4p ESCRT proteins for viral replicase complex assembly.
Asunto(s)
Arabidopsis/enzimología , Interacciones Huésped-Patógeno , ARN Polimerasa Dependiente del ARN/metabolismo , Saccharomyces cerevisiae/enzimología , Tombusvirus/fisiología , Enzimas Ubiquitina-Conjugadoras/metabolismo , Replicación Viral , Arabidopsis/virología , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Eliminación de Gen , Prueba de Complementación Genética , Unión Proteica , Mapeo de Interacción de Proteínas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/virología , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMEN
KEY MESSAGE: Using a high-resolution mapping approach, we identified a candidate gene for ZYMV resistance in cucumber. Our findings should assist the development of high-versatility molecular markers for MAS for ZYMV resistance. Zucchini yellow mosaic virus (ZYMV) causes significant disease, which leads to fruit yield loss in cucurbit crops. Since ZYMV resistance is often inherited recessively in cucumber, marker-assisted selection (MAS) is a useful tool for the development of resistant cucumber cultivars. Using 128 families of an F2:3 population derived from a cross between susceptible 'CS-PMR1' and resistant 'A192-18' cucumber inbred lines, we confirmed that ZYMV resistance is conferred by a single recessive locus: zym (A192-18) . We constructed a cucumber genetic linkage map that included 125 simple sequence repeat (SSR) markers segregating into 7 linkage groups (chromosomes). The zym (A192-18) locus was mapped to chromosome 6, at genetic distances of 0.9 and 1.3 cM from two closely linked SSR markers. For high-resolution genetic mapping, we identified new molecular markers cosegregating with the zym (A192-18) locus; using cucumber genomic and molecular marker resources and screening an F2 population of 2,429 plants, we narrowed down the zym (A192-18) locus to a <50-kb genomic region flanked by two SSR markers, which included six candidate genes. Sequence analysis of the candidate genes' coding regions revealed that the vacuolar protein sorting-associated protein 4-like (VPS4-like) gene had two SNPs between the parental lines. Based on SNPs of the VPS-4-like gene, we developed zym (A192-18) -linked DNA markers and found that genotypes associated with these markers were correlated with the ZYMV resistance phenotype in 48 cucumber inbred lines. According to our data, the gene encoding VPS4-like protein is a candidate for the zym (A192-18) locus. These results may be valuable for MAS for ZYMV resistance in cucumber.
Asunto(s)
Mapeo Cromosómico , Cucumis sativus/genética , Cucurbita/genética , Resistencia a la Enfermedad/genética , Genes de Plantas/genética , Genes Recesivos , Enfermedades de las Plantas/genética , Potyvirus/fisiología , Secuencia de Aminoácidos , Secuencia de Bases , Cromosomas de las Plantas , Cucumis sativus/virología , Cucurbita/virología , ADN de Plantas/genética , Marcadores Genéticos/genética , Repeticiones de Microsatélite/genética , Datos de Secuencia Molecular , Fenotipo , Filogenia , Enfermedades de las Plantas/virología , Polimorfismo de Nucleótido Simple/genética , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido NucleicoRESUMEN
Transcription factors of the DRE-Binding1 (DREB1)/C-repeat binding factor family specifically interact with a cis-acting dehydration-responsive element/C-repeat involved in low-temperature stress-responsive gene expression in Arabidopsis (Arabidopsis thaliana). Expression of DREB1s is induced by low temperatures and is regulated by the circadian clock under unstressed conditions. Promoter sequences of DREB1s contain six conserved motifs, boxes I to VI. We analyzed the promoter region of DREB1C using transgenic plants and found that box V with the G-box sequence negatively regulates DREB1C expression under circadian control. The region around box VI contains positive regulatory elements for low-temperature-induced expression of DREB1C. Using yeast one-hybrid screens, we isolated cDNA encoding the transcriptional factor Phytochrome-Interacting Factor7 (PIF7), which specifically binds to the G-box of the DREB1C promoter. The PIF7 gene was expressed in rosette leaves, and the PIF7 protein was localized in the nuclei of the cells. Transactivation experiments using Arabidopsis protoplasts indicated that PIF7 functions as a transcriptional repressor for DREB1C expression and that its activity is regulated by PIF7-interacting factors TIMING OF CAB EXPRESSION1 and Phytochrome B, which are components of the circadian oscillator and the red light photoreceptor, respectively. Moreover, in the pif7 mutant, expression of DREB1B and DREB1C was not repressed under light conditions, indicating that PIF7 functions as a transcriptional repressor for the expression of DREB1B and DREB1C under circadian control. This negative regulation of DREB1 expression may be important for avoiding plant growth retardation by the accumulation of DREB1 proteins under unstressed conditions.
Asunto(s)
Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Ritmo Circadiano/genética , Proteínas de Unión al ADN/metabolismo , Regulación de la Expresión Génica de las Plantas , Fitocromo/metabolismo , Factores de Transcripción/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/aislamiento & purificación , Emparejamiento Base/genética , Secuencia de Bases , Análisis Mutacional de ADN , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/aislamiento & purificación , Genes de Plantas/genética , Modelos Genéticos , Datos de Secuencia Molecular , Mutación/genética , Hojas de la Planta/citología , Hojas de la Planta/genética , Regiones Promotoras Genéticas/genética , Unión Proteica , Transporte de Proteínas , Protoplastos/metabolismo , Fracciones Subcelulares/metabolismo , Factores de Transcripción/metabolismo , Transcripción Genética , Activación Transcripcional/genéticaRESUMEN
Arabis mosaic virus lily and narcissus isolates (ArMV-Li and ArMV-Na) induced severe necrotic spots on Chenopodium quinoa, whereas ArMV butterbur isolate (ArMV-Bu) caused symptomless infection in the plant. The accumulation level of ArMV-Bu in upper non-inoculated leaves of C. quinoa was comparable to that of ArMV-Li or -Na. The agar gel double-diffusion test using an antiserum against ArMV-Li showed ArMV-Li was closely related to ArMV-Na, but not to ArMV-Bu. The RNAs-2 of ArMV-Li, -Na, and -Bu consist of 3707, 3709, and 3789 nucleotides, and they contain one open reading frame encoding a putative polyprotein of 1083, 1084, and 1122 amino acids, respectively. The overall identity of RNA-2 of ArMV-Li displayed more than 90% with ArMV-Na, but less than 70% with ArMV-Bu. A phylogenetic analysis of 2A sequences from ArMV isolates revealed ArMV-Bu was not categorized in any cluster. ArMV-Bu is a unique isolate from the point of view of pathological and serological features, and nucleotide sequence.
Asunto(s)
Chenopodium quinoa/virología , Nepovirus/genética , Nepovirus/patogenicidad , Enfermedades de las Plantas/virología , ARN Viral/genética , Japón , Datos de Secuencia Molecular , Nepovirus/clasificación , Nepovirus/aislamiento & purificación , FilogeniaRESUMEN
The Burkholderia multivorans strain ATCC 17616 carries three circular chromosomes with sizes of 3.4, 2.5, and 0.9 Mb. To reveal the distribution and organization of the genes for fundamental cell functions on the genome of this bacterium, the dnaA and dnaK gene regions of ATCC 17616 were cloned and characterized. The gene organization of the dnaA region was rnpA-rmpH-dnaA-dnaN-gyrB with a single consensus DnaA-binding box (TTATCCACA) between the rmpH and dnaA genes. This intergenic region, however, did not work as an autonomously replicating sequence in ATCC 17616. On the other hand, the gene organization of the dnaK region was grpE-orf1 (gene for thioredoxin homologue)-dnaK-dnaJ-pabB (gene for p-aminobenzoate synthetase component homologue). A putative heat-shock promoter that showed good homology to the sigma32-dependent promoter consensus sequence in Escherichia coli was found upstream of the grpE gene, suggesting that these five genes constitute an operon. In M9 succinate minimal medium the dnaJ mutant grew more slowly than the wild-type strain, indicating that this operon is functional. Pulsed-field gel electrophoresis and Southern blot analyses indicated that both the dnaA and dnaK gene regions exist as single copies on the 3.4 Mb chromosome.
Asunto(s)
Proteínas Bacterianas/genética , Burkholderia/genética , Mapeo Cromosómico/métodos , Cromosomas Bacterianos/genética , Proteínas de Unión al ADN/genética , Proteínas de Escherichia coli/genética , Proteínas HSP70 de Choque Térmico/genética , Secuencia de Bases , Burkholderia/clasificación , Dosificación de Gen , Datos de Secuencia Molecular , Especificidad de la EspecieRESUMEN
The Burkholderia multivorans strain ATCC 17616 carries three circular chromosomes with sizes of 3.4, 2.5, and 0.9 Mb. To determine the distribution and organization of the amino acid biosynthetic genes on the genome of this beta-proteobacterium, various auxotrophic mutations were isolated using a Tn5 derivative that was convenient not only for the determination of its insertion site on the genome map but also for the structural analysis of the flanking regions. Analysis by pulsed-field gel electrophoresis revealed that 20 out of 23 insertion mutations were distributed on the 3.4-Mb chromosome. More detailed analysis of the his, trp, arg, and lys mutations and their flanking regions revealed the following properties of these auxotrophic genes: (i) all nine his genes were clustered on the 3.4-Mb chromosome; (ii) seven trp genes were organized within two distinct regions, i.e., a trpEGDC cluster on the 3.4-Mb chromosome and a trpFBA cluster on the 2.5-Mb chromosome; (iii) the leu gene cluster, leuCDB, was also located close to the trpFBA cluster; and (iv) lysA and argG genes were located on the 2.5-Mb chromosome, in contrast to the argH gene, which was located on the 3.4-Mb chromosome. Southern hybridization analysis, allelic exchange mutagenesis of ATCC 17616, and complementation tests demonstrated that all of the genes examined were functional and existed as a single copy within the genome. The present findings also indicated that the 2.5-Mb chromosome carried various auxotrophic genes with no structural or functional counterparts on the remaining two chromosomes.