zur Suche springenzur Navigation springenzum Inhalt springen

Publikationen - Molekulare Signalverarbeitung

Sortieren nach: Erscheinungsjahr Typ der Publikation

Zeige Ergebnisse 1 bis 10 von 11.

Publikation

Serra, P.; Carbonell, A.; Navarro, B.; Gago-Zachert, S.; Li, S.; Di Serio, F.; Flores, R.; Symptomatic plant viroid infections in phytopathogenic fungi: A request for a critical reassessment Proc. Natl. Acad. Sci. U.S.A. 117, 10126-10128, (2020) DOI: 10.1073/pnas.1922249117

0
Bücher und Buchkapitel

Carbonell, A.; Flores, R.; Gago, S.; Hammerhead Ribozymes Against Virus and Viroid RNAs (Erdmann, V. A. & Barciszewski, J., eds.). RNA Technologies 411-427, (2012) ISBN: 978-3-642-27426-8 DOI: 10.1007/978-3-642-27426-8_16

The hammerhead ribozyme, a small catalytic motif that promotes self-cleavage of the RNAs in which it is found naturally embedded, can be manipulated to recognize and cleave specifically in trans other RNAs in the presence of Mg2+. To be really effective, hammerheads need to operate at the low concentration of Mg2+ existing in vivo. Evidence has been gathered along the last years showing that tertiary stabilizing motifs (TSMs), particularly interactions between peripheral loops, are critical for the catalytic activity of hammerheads at physiological levels of Mg2+. These TSMs, in two alternative formats, have been incorporated into a new generation of more efficient trans-cleaving hammerheads, some of which are active in vitro and in planta when targeted against the highly structured RNA of a viroid (a small plant pathogen). This strategy has potential to confer protection against other RNA replicons, like RNA viruses infecting plants and animals.
Publikation

Carbonell, A.; Flores, R.; Gago, S.; Trans-cleaving hammerhead ribozymes with tertiary stabilizing motifs: in vitro and in vivo activity against a structured viroid RNA Nucleic Acids Res. 39, 2432-2444, (2011) DOI: 10.1093/nar/gkq1051

Trans -cleaving hammerheads with discontinuous or extended stem I and with tertiary stabilizing motifs (TSMs) have been tested previously against short RNA substrates in vitro at low Mg 2+ concentration. However, the potential of these ribozymes for targeting longer and structured RNAs in vitro and in vivo has not been examined. Here, we report the in vitro cleavage of short RNAs and of a 464-nt highly structured RNA from potato spindle tuber viroid (PSTVd) by hammerheads with discontinuous and extended formats at submillimolar Mg 2+ . Under these conditions, hammerheads derived from eggplant latent viroid and peach latent mosaic viroid (PLMVd) with discontinuous and extended formats, respectively, where the most active. Furthermore, a PLMVd-derived hammerhead with natural TSMs showed activity in vivo against the same long substrate and interfered with systemic PSTVd infection, thus reinforcing the idea that this class of ribozymes has potential to control pathogenic RNA replicons.
Publikation

Asquini, E.; Gerdol, M.; Gasperini, D.; Igic, B.; Graziosi, G.; Pallavicini, A.; S-RNase-like Sequences in Styles of Coffea (Rubiaceae). Evidence for S-RNase Based Gametophytic Self-Incompatibility? Trop. Plant Biol. 4, 237-249, (2011) DOI: 10.1007/s12042-011-9085-2

Although RNase-based self-incompatibility (SI) is suspected to operate in a wide group of plant families, it has been characterized as the molecular genetic basis of SI in only three distantly related families, Solanaceae, Plantaginaceae, and Rosaceae, all described over a decade ago. Previous studies found that gametophytic SI, controlled by a multi-allelic S-locus, operates in the coffee family (Rubiaceae). The molecular genetic basis of this mechanism remains unknown, despite the immense importance of coffee as an agricultural commodity. Here, we isolated ten sequences with features of T2-S-type RNases from two Coffea species. While three of the sequences were identified in both species and clearly do not appear to be S-locus products, our data suggest that six sequences may be S-alleles in the self-incompatible C. canephora, and one may be a relict in the self-compatible C. arabica. We demonstrate that these sequences show style-specific expression, display polymorphism in C. canephora, and cluster with S-locus products in a phylogenetic analysis that includes other plant families with RNase-based SI. Although our results are not definitive, in part because the available plant materials were limited and data patterns relatively complex, our results strongly hint that RNase-based SI mechanism operates in the Rubiaceae family.
Publikation

Flores, R.; Gas, M.-E.; Molina-Serrano, D.; Nohales, M.-?.; Carbonell, A.; Gago, S.; De la Peña, M.; Daròs, J.-A.; Viroid Replication: Rolling-Circles, Enzymes and Ribozymes Viruses 1, 317-334, (2009) DOI: 10.3390/v1020317

Viroids, due to their small size and lack of protein-coding capacity, must rely essentially on their hosts for replication. Intriguingly, viroids have evolved the ability to replicate in two cellular organella, the nucleus (family Pospiviroidae) and the chloroplast (family Avsunviroidae). Viroid replication proceeds through an RNA-based rolling-circle mechanism with three steps that, with some variations, operate in both polarity strands: i) synthesis of longer-than-unit strands catalyzed by either the nuclear RNA polymerase II or a nuclear-encoded chloroplastic RNA polymerase, in both instances redirected to transcribe RNA templates, ii) cleavage to unit-length, which in the family Avsunviroidae is mediated by hammerhead ribozymes embedded in both polarity strands, while in the family Pospiviroidae the oligomeric RNAs provide the proper conformation but not the catalytic activity, and iii) circularization. The host RNA polymerases, most likely assisted by additional host proteins, start transcription from specific sites, thus implying the existence of viroid promoters. Cleavage and ligation in the family Pospiviroidae is probably catalyzed by an RNase III-like enzyme and an RNA ligase able to circularize the resulting 5’ and 3’ termini. Whether a chloroplastic RNA ligase mediates circularization in the family Avsunviroidae, or this reaction is autocatalytic, remains an open issue.
Publikation

Carbonell, A.; Martínez de Alba, A.-E.; Flores, R.; Gago, S.; Double-stranded RNA interferes in a sequence-specific manner with the infection of representative members of the two viroid families Virology 371, 44-53, (2008) DOI: 10.1016/j.virol.2007.09.031

Infection by viroids, non-protein-coding circular RNAs, occurs with the accumulation of 21–24 nt viroid-derived small RNAs (vd-sRNAs) with characteristic properties of small interfering RNAs (siRNAs) associated to RNA silencing. The vd-sRNAs most likely derive from dicer-like (DCL) enzymes acting on viroid-specific dsRNA, the key elicitor of RNA silencing, or on the highly structured genomic RNA. Previously, viral dsRNAs delivered mechanically or agroinoculated have been shown to interfere with virus infection in a sequence-specific manner. Here, we report similar results with members of the two families of nuclear- and chloroplast-replicating viroids. Moreover, homologous vd-sRNAs co-delivered mechanically also interfered with one of the viroids examined. The interference was sequence-specific, temperature-dependent and, in some cases, also dependent on the dose of the co-inoculated dsRNA or vd-sRNAs. The sequence-specific nature of these effects suggests the involvement of the RNA induced silencing complex (RISC), which provides sequence specificity to RNA silencing machinery. Therefore, viroid titer in natural infections might be regulated by the concerted action of DCL and RISC. Viroids could have evolved their secondary structure as a compromise between resistance to DCL and RISC, which act preferentially against RNAs with compact and relaxed secondary structures, respectively. In addition, compartmentation, association with proteins or active replication might also help viroids to elude their host RNA silencing machinery.
Bücher und Buchkapitel

Flores, R.; Carbonell, A.; Gago, S.; Martínez de Alba, A.-E.; Delgado, S.; Rodio, M.-E.; Di Serio, F.; Viroid-host interactions: A molecular dialogue between two uneven partners Biology of Plant-Microbe Interactions 6, 1-9, (2008)

0
Bücher und Buchkapitel

Flores, R.; Carbonell, A.; De la Peña, M.; Gago, S.; RNAs Autocatalíticos: Ribozimas de Cabeza de Martillo 407-425, (2007)

0
Publikation

De Nardi, B.; Dreos, R.; Del Terra, L.; Martellossi, C.; Asquini, E.; Tornincasa, P.; Gasperini, D.; Pacchioni, B.; Rathinavelu, R.; Pallavicini, A.; Graziosi, G.; Differential responses of Coffea arabica L. leaves and roots to chemically induced systemic acquired resistance Genome 49, 1594-1605, (2006) DOI: 10.1139/g06-125

Coffea arabica is susceptible to several pests and diseases, some of which affect the leaves and roots. Systemic acquired resistance (SAR) is the main defence mechanism activated in plants in response to pathogen attack. Here, we report the effects of benzo(1,2,3)thiadiazole-7-carbothioic acid-s-methyl ester (BTH), a SAR chemical inducer, on the expression profile of C. arabica. Two cDNA libraries were constructed from the mRNA isolated from leaves and embryonic roots to create 1587 nonredundant expressed sequence tags (ESTs). We developed a cDNA microarray containing 1506 ESTs from the leaves and embryonic roots, and 48 NBS-LRR (nucleotide-binding site leucine-rich repeat) gene fragments derived from 2 specific genomic libraries. Competitive hybridization between untreated and BTH-treated leaves resulted in 55 genes that were significantly overexpressed and 16 genes that were significantly underexpressed. In the roots, 37 and 42 genes were over and underexpressed, respectively. A general shift in metabolism from housekeeping to defence occurred in the leaves and roots after BTH treatment. We observed a systemic increase in pathogenesis-related protein synthesis, in the oxidative burst, and in the cell wall strengthening processes. Moreover, responses in the roots and leaves varied significantly.
Publikation

Carbonell, A.; De la Peña, M.; Flores, R.; Gago, S.; Effects of the trinucleotide preceding the self-cleavage site on eggplant latent viroid hammerheads: differences in co- and post-transcriptional self-cleavage may explain the lack of trinucleotide AUC in most natural hammerheads Nucleic Acids Res. 34, 5613-5622, (2006) DOI: 10.1093/nar/gkl717

Eggplant latent viroid (ELVd) can form stable hammerhead structures in its (+) and (−) strands. These ribozymes have the longest helices I reported in natural hammerheads, with that of the ELVd (+) hammerhead being particularly stable (5/7 bp are G-C). Moreover, the trinucleotide preceding the self-cleavage site of this hammerhead is AUA, which together with GUA also found in some natural hammerheads, deviate from the GUC present in most natural hammerheads including the ELVd (−) hammerhead. When the AUA trinucleotide preceding the self-cleavage site of the ELVd (+) hammerhead was substituted by GUA and GUC, as well as by AUC (essentially absent in natural hammerheads), the values of the self-cleavage rate constants at low magnesium of the purified hammerheads were: ELVd-(+)-AUC≈ELVd-(+)-GUC>ELVd-(+)-GUA> ELVd-(+)-AUA. However, the ELVd-(+)-AUC hammerhead was the catalytically less efficient during in vitro transcription, most likely because of the transient adoption of catalytically-inactive metastable structures. These results suggest that natural hammerheads have been evolutionary selected to function co-transcriptionally, and provide a model explaining the lack of trinucleotide AUC preceding the self-cleavage site of most natural hammerheads. Comparisons with other natural hammerheads showed that the ELVd-(+)-GUC and ELVd-(+)-AUC hammerheads are the catalytically most active in a post-transcriptional context with low magnesium.
  • Die Leibniz-Gemeinschaft
  • Digitalisierung in der Landwirtschaft
  • Martin-Luther Universität Halle
IPB Mainnav Search