RESUMO
Endogenous viral elements (EVEs) are viral sequences that are integrated in the nuclear genomes of their hosts and are signatures of viral infections that may have occurred millions of years ago. The study of EVEs, coined paleovirology, provides important insights into virus evolution. The Caulimoviridae is the most common group of EVEs in plants, although their presence has often been overlooked in plant genome studies. We have refined methods for the identification of caulimovirid EVEs and interrogated the genomes of a broad diversity of plant taxa, from algae to advanced flowering plants. Evidence is provided that almost every vascular plant (tracheophyte), including the most primitive taxa (clubmosses, ferns and gymnosperms) contains caulimovirid EVEs, many of which represent previously unrecognized evolutionary branches. In angiosperms, EVEs from at least one and as many as five different caulimovirid genera were frequently detected, and florendoviruses were the most widely distributed, followed by petuviruses. From the analysis of the distribution of different caulimovirid genera within different plant species, we propose a working evolutionary scenario in which this family of viruses emerged at latest during Devonian era (approx. 320 million years ago) followed by vertical transmission and by several cross-division host swaps.
Assuntos
Caulimoviridae/genética , DNA Viral/genética , Análise de Sequência de DNA/métodos , Traqueófitas/genética , Evolução Molecular , Genoma de Planta , Interações Hospedeiro-Patógeno , Filogenia , Traqueófitas/virologiaRESUMO
Pokeweed antiviral protein (PAP) is a ribosome inactivating protein (RIP) that depurinates the sarcin/ricin loop (SRL) of rRNA, inhibiting protein synthesis. PAP depurinates viral RNA, and in doing so, lowers the infectivity of many plant viruses. The mechanism by which PAP accesses uncapped viral RNA is not known, impeding scientists from developing effective antiviral agents for the prevention of the diseases caused by uncapped RNA viruses. Kinetic rates of PAP interacting with tobacco etch virus (TEV) RNA, in the presence and absence of eIFiso4F, were examined, addressing how the eIF affects selective PAP targeting and depurination of the uncapped viral RNA. PAP-eIFs copurification assay and fluorescence resonance energy transfer demonstrate that PAP forms a ternary complex with the eIFiso4G and eIFiso4E, directing the depurination of uncapped viral RNA. eIFiso4F selectively targets PAP to depurinate TEV RNA by increasing PAP's specificity constant for uncapped viral RNA 12-fold, when compared to the depurination of an oligonucleotide RNA that mimics the SRL of large rRNA, and cellular capped luciferase mRNA. This explains how PAP is able to lower infectivity of pokeweed viruses, while preserving its own ribosomes and cellular RNA from depurination: PAP utilizes cellular eIFiso4F in a novel strategy to target uncapped viral RNA. It may be possible to modulate and utilize these PAP-eIFs interactions for their public health benefit; by repurposing them to selectively target PAP to depurinate uncapped viral RNA, many plant and animal diseases caused by these viruses could be alleviated.
Assuntos
Fatores de Iniciação de Peptídeos/metabolismo , Proteínas de Plantas/metabolismo , Potyvirus/metabolismo , RNA Viral/metabolismo , Proteínas Inativadoras de Ribossomos Tipo 1/metabolismo , Traqueófitas/virologia , Iniciação Traducional da Cadeia Peptídica , Fatores de Iniciação de Peptídeos/genética , Proteínas de Plantas/genética , Potyvirus/genética , Purinas/química , Capuzes de RNA/genética , Capuzes de RNA/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Viral/genética , Proteínas Inativadoras de Ribossomos Tipo 1/antagonistas & inibidores , Ribossomos/genética , Ribossomos/metabolismoRESUMO
It is known that the most suitable plant indicator targets for radiation pollution biomonitoring are conifers, because they have high radiosensitivity. In this review are briefly considered previously accumulated information about the genetic nature of morphological abnormalities in gymnosperms, induced by acute and chronic irradiation in the exclusion zone of the Chornobyl nuclear power plant. Since in the last decade appeared additional number of important research results, dedicated to the analysis of molecular biological and molecular genetic effects of chronic irradiation on the coniferous plants growing in the exclusion zone of the Chornobyl disaster, all these results are also analyzed in current review.
Assuntos
Adaptação Fisiológica/genética , Aberrações Cromossômicas/efeitos da radiação , Raios gama/efeitos adversos , Genes de Plantas , Mutação/efeitos da radiação , Traqueófitas/efeitos da radiação , Acidente Nuclear de Chernobyl , Relação Dose-Resposta à Radiação , Monitoramento Ambiental , Epigênese Genética , Tolerância a Radiação/genética , Radioisótopos/análise , Estresse Fisiológico , Traqueófitas/genética , Traqueófitas/microbiologia , Traqueófitas/virologia , UcrâniaRESUMO
A putative new endornavirus was isolated from Malabar spinach (Basella alba). The viral dsRNA consisted of 14,027 nt with a single ORF that coded for a polyprotein of 4,508 aa. The genome organization was similar to that of four other endornaviruses. Conserved domains for helicase-1, capsular synthase, UDP-glucose-glycosyltransferase (UGT), and RdRp were detected. Infected plants were phenotypically undistinguishable from healthy ones. The name Basella alba endornavirus is proposed for the virus isolated from Malabar spinach.