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URI permanente para esta coleçãohttps://locus.ufv.br/handle/123456789/11847
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Item NIK1-mediated translation suppression functions as a plant antiviral immunity mechanism(Nature, 2015-04-30) Zorzatto, Cristiane; Machado, João Paulo B.; Lopes, Kênia V. G.; Nascimento, Kelly J. T.; Pereira, Welison A.; Brustolini, Otávio J. B.; Reis, Pedro A. B.; Calil, Iara P.; Deguchi, Michihito; Sachetto-Martins, Gilberto; Gouveia, Bianca C.; Loriato, Virgílio A. P.; Silva, Marcos A. C.; Silva, Fabyano F.; Santos, Anésia A.; Chory, Joanne; Fontes, Elizabeth P. B.Plants and plant pathogens are subject to continuous co-evolutionary pressure for dominance, and the outcomes of these interactions can substantially impact agriculture and food security^ 1–3 . In virus– plant interactions, one of the major mechanisms for plant antiviral immunity relies on RNA silencing, which is often suppressed by co-evolving virus suppressors, thus enhancing viral pathogenicity in susceptible hosts^ 1 . In addition, plants use the nucleotide-binding and leucine-rich repeat (NB-LRR) domain-containing resistance proteins, which recognize viral effectors to activate effector-triggered immunity in a defence mechanism similar to that employed in non-viral infections^ 2,3 . Unlike most eukaryotic organisms, plants are not known to activate mechanisms of host global translation suppression to fight viruses^ 1,2 . Here we demonstrate in Arabidopsis that the constitutive activation of NIK1, a leucine-rich repeat receptor-like kinase (LRR-RLK) identified as a virulence target of the begomovirus nuclear shuttle protein (NSP)^ 4–6 , leads to global translation suppression and translocation of the downstream component RPL10 to the nucleus, where it interacts with a newly identified MYB-like protein, L10-INTERACTING MYB DOMAIN-CONTAINING PROTEIN (LIMYB), to downregulate translational machinery genes fully. LIMYB overexpression represses ribosomal protein genes at the transcriptional level, resulting in protein synthesis inhibition, decreased viral messenger RNA association with polysome fractions and enhanced tolerance to begomovirus. By contrast, the loss of LIMYB function releases the repression of translation-related genes and increases susceptibility to virus infection. Therefore, LIMYB links immune receptor LRR-RLK activation to global translation suppression as an antiviral immunity strategy in plants.Item A novel transcription factor, ERD15 (Early Responsive to Dehydration 15), connects Endoplasmic Reticulum stress with an osmotic stress-induced cell death signal(The Journal of Biological Chemistry, 2011-04-11) Alves, Murilo S.; Reis, Pedro A. B.; Dadalto, Silvana P.; Faria, Jerusa A. Q. A.; Fontes, Elizabeth P. B.; Fietto, Luciano G.As in all other eukaryotic organisms, endoplasmic reticulum (ER) stress triggers the evolutionarily conserved unfolded protein response in soybean, but it also communicates with other adaptive signaling responses, such as osmotic stress-induced and ER stress-induced programmed cell death. These two signaling pathways converge at the level of gene transcription to activate an integrated cascade that is mediated by N-rich proteins (NRPs). Here, we describe a novel transcription factor, GmERD15 (Glycine max Early Responsive to Dehydration 15), which is induced by ER stress and osmotic stress to activate the expression of NRP genes. GmERD15 was isolated because of its capacity to stably associate with the NRP-B promoter in yeast. It specifically binds to a 187-bp fragment of the NRP-B promoter in vitro and activates the transcription of a reporter gene in yeast. Furthermore, GmERD15 was found in both the cytoplasm and the nucleus, and a ChIP assay revealed that it binds to the NRP-B promoter in vivo. Expression of GmERD15 in soybean protoplasts activated the NRP-B promoter and induced expression of the NRP-B gene. Collectively, these results support the interpretation that GmERD15 functions as an upstream component of stress-induced NRP-B-mediated signaling to connect stress in the ER to an osmotic stress-induced cell death signal.