scholarly journals A class of independently evolved transcriptional repressors in plant RNA viruses facilitates viral infection and vector feeding

2021 ◽  
Vol 118 (11) ◽  
pp. e2016673118
Author(s):  
Lulu Li ◽  
Hehong Zhang ◽  
Changhai Chen ◽  
Haijian Huang ◽  
Xiaoxiang Tan ◽  
...  
Keyword(s):  
Viral Infection ◽  
Transcriptional Activation ◽  
Rna Viruses ◽  
Plant Viruses ◽  
Transcriptional Repressors ◽  
Successful Infection ◽  
Common Strategy ◽  
Ja Signaling ◽  
Repressor Activity ◽  
Rice Viruses

Plant viruses employ diverse virulence strategies to achieve successful infection, but there are few known general strategies of viral pathogenicity and transmission used by widely different plant viruses. Here, we report a class of independently evolved virulence factors in different plant RNA viruses which possess active transcriptional repressor activity. Rice viruses in the genera Fijivirus, Tenuivirus, and Cytorhabdovirus all have transcriptional repressors that interact in plants with the key components of jasmonic acid (JA) signaling, namely mediator subunit OsMED25, OsJAZ proteins, and OsMYC transcription factors. These transcriptional repressors can directly disassociate the OsMED25-OsMYC complex, inhibit the transcriptional activation of OsMYC, and then combine with OsJAZ proteins to cooperatively attenuate the JA pathway in a way that benefits viral infection. At the same time, these transcriptional repressors efficiently enhanced feeding by the virus insect vectors by repressing JA signaling. Our findings reveal a common strategy in unrelated plant viruses in which viral transcriptional repressors hijack and repress the JA pathway in favor of both viral pathogenicity and vector transmission.

scholarly journals Distinct modes of manipulation of rice auxin response factor OsARF17 by different plant RNA viruses for infection

2020 ◽  
Vol 117 (16) ◽  
pp. 9112-9121 ◽  
Author(s):  
Hehong Zhang ◽  
Lulu Li ◽  
Yuqing He ◽  
Qingqing Qin ◽  
Changhai Chen ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Transcriptional Activation ◽  
Rna Viruses ◽  
Rna Virus ◽  
Viral Proteins ◽  
Plant Viruses ◽  
Auxin Response Factor ◽  
Auxin Signaling ◽  
Response Factor ◽  
Auxin Response

Plant auxin response factor (ARF) transcription factors are an important class of key transcriptional modulators in auxin signaling. Despite the well-studied roles of ARF transcription factors in plant growth and development, it is largely unknown whether, and how, ARF transcription factors may be involved in plant resistance to pathogens. We show here that two fijiviruses (double-stranded RNA viruses) utilize their proteins to disturb the dimerization of OsARF17 and repress its transcriptional activation ability, while a tenuivirus (negative-sense single-stranded RNA virus) directly interferes with the DNA binding activity of OsARF17. These interactions impair OsARF17-mediated antiviral defense. OsARF17 also confers resistance to a cytorhabdovirus and was directly targeted by one of the viral proteins. Thus, OsARF17 is the common target of several very different viruses. This suggests that OsARF17 plays a crucial role in plant defense against different types of plant viruses, and that these viruses use independently evolved viral proteins to target this key component of auxin signaling and facilitate infection.

scholarly journals Ultrastructural Features of Membranous Replication Organelles Induced by Positive-Stranded RNA Viruses

Cells ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 2407
Author(s):  
Van Nguyen-Dinh ◽  
Eva Herker
Keyword(s):  
Rna Viruses ◽  
Scientific Progress ◽  
Membrane System ◽  
Building Blocks ◽  
Surveillance Systems ◽  
Animal Cells ◽  
Cell Organelles ◽  
Positive Strand ◽  
Successful Infection ◽  
Positive Strand Rna

All intracellular pathogens critically depend on host cell organelles and metabolites for successful infection and replication. One hallmark of positive-strand RNA viruses is to induce alterations of the (endo)membrane system in order to shield their double-stranded RNA replication intermediates from detection by the host cell’s surveillance systems. This spatial seclusion also allows for accruing host and viral factors and building blocks required for efficient replication of the genome and prevents access of antiviral effectors. Even though the principle is iterated by almost all positive-strand RNA viruses infecting plants and animals, the specific structure and the organellar source of membranes differs. Here, we discuss the characteristic ultrastructural features of the virus-induced membranous replication organelles in plant and animal cells and the scientific progress gained by advanced microscopy methods.

scholarly journals Activation of RNase L in Egyptian Rousette Bat-Derived RoNi/7 Cells Is Dependent Primarily on OAS3 and Independent of MAVS Signaling

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Yize Li ◽  
Beihua Dong ◽  
Zuzhang Wei ◽  
Robert H. Silverman ◽  
Susan R. Weiss
Keyword(s):  
Antiviral Activity ◽  
Viral Replication ◽  
Viral Infection ◽  
Rna Viruses ◽  
Primary Response ◽  
Human Cells ◽  
Secondary Effect ◽  
Rnase L ◽  
Interferon Signaling ◽  
Highly Pathogenic

ABSTRACT Bats are reservoirs for many RNA viruses that are highly pathogenic in humans yet relatively apathogenic in the natural host. It has been suggested that differences in innate immunity are responsible. The antiviral OAS-RNase L pathway is well characterized in humans, but there is little known about its activation and antiviral activity in bats. During infection, OASs, upon sensing double-stranded RNA (dsRNA), produce 2′-5′ oligoadenylates (2-5A), leading to activation of RNase L which degrades viral and host RNA, limiting viral replication. Humans encode three active OASs (OAS1 to -3). Analysis of the Egyptian Rousette bat genome combined with mRNA sequencing from bat RoNi/7 cells revealed three homologous OAS proteins. Interferon alpha treatment or viral infection induced all three OAS mRNAs, but RNase L mRNA is constitutively expressed. Sindbis virus (SINV) or vaccinia virus (VACVΔE3L) infection of wild-type (WT) or OAS1-KO (knockout), OAS2-KO, or MAVS-KO RoNi/7 cells, but not RNase L-KO or OAS3-KO cells, induces robust RNase L activation. SINV replication is 100- to 200-fold higher in the absence of RNase L or OAS3 than in WT cells. However, MAVS-KO had no detectable effect on RNA degradation or replication. Thus, in RoNi/7 bat cells, as in human cells, activation of RNase L during infection and its antiviral activity are dependent primarily on OAS3 while MAVS signaling is not required for the activation of RNase L and restriction of infection. Our findings indicate that OAS proteins serve as pattern recognition receptors (PRRs) to recognize viral dsRNA and that this pathway is a primary response to virus rather than a secondary effect of interferon signaling. IMPORTANCE Many RNA viruses that are highly pathogenic in humans are relatively apathogenic in their bat reservoirs, making it important to compare innate immune responses in bats to those well characterized in humans. One such antiviral response is the OAS-RNase L pathway. OASs, upon sensing dsRNA, produce 2-5A, leading to activation of RNase L which degrades viral and host RNA, limiting viral replication. Analysis of Egyptian Rousette bat sequences revealed three OAS genes expressing OAS1, OAS2, and OAS3 proteins. Interferon treatment or viral infection induces all three bat OAS mRNAs. In these bat cells as in human cells, RNase L activation and its antiviral activity are dependent primarily on OAS3 while MAVS signaling is not required. Importantly, our findings indicate the OAS-RNase L system is a primary response to virus rather than a secondary effect of interferon signaling and therefore can be activated early in infection or while interferon signaling is antagonized.

scholarly journals Arbuscular Mycorrhizal Symbiosis Affects Plant Immunity to Viral Infection and Accumulation

Viruses ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 534 ◽  
Author(s):  
Zhipeng Hao ◽  
Wei Xie ◽  
Baodong Chen
Keyword(s):  
Viral Infection ◽  
Plant Immunity ◽  
Arbuscular Mycorrhizal ◽  
Am Fungi ◽  
Plant Viruses ◽  
Limiting Factors ◽  
Systemic Resistance ◽  
Mycorrhizal Symbiosis ◽  
Complex Nature ◽  
Terrestrial Plants

Arbuscular mycorrhizal (AM) fungi, as root symbionts of most terrestrial plants, improve plant growth and fitness. In addition to the improved plant nutritional status, the physiological changes that trigger metabolic changes in the root via AM fungi can also increase the host ability to overcome biotic and abiotic stresses. Plant viruses are one of the important limiting factors for the commercial cultivation of various crops. The effect of AM fungi on viral infection is variable, and considerable attention is focused on shoot virus infection. This review provides an overview of the potential of AM fungi as bioprotection agents against viral diseases and emphasizes the complex nature of plant–fungus–virus interactions. Several mechanisms, including modulated plant tolerance, manipulation of induced systemic resistance (ISR), and altered vector pressure are involved in such interactions. We propose that using “omics” tools will provide detailed insights into the complex mechanisms underlying mycorrhizal-mediated plant immunity.

scholarly journals Anaphase promoting complex–dependent degradation of transcriptional repressors Nrm1 and Yhp1 in Saccharomyces cerevisiae

2011 ◽  
Vol 22 (13) ◽  
pp. 2175-2184 ◽  
Author(s):  
Denis Ostapenko ◽  
Mark J. Solomon
Keyword(s):  
Cell Cycle ◽  
Transcriptional Activation ◽  
Target Genes ◽  
Full Range ◽  
Transcriptional Repressors ◽  
Anaphase Promoting Complex ◽  
Dependent Protein Kinase ◽  
Proteomic Screen ◽  
Dependent Protein ◽  
Cellular Pathways

The anaphase-promoting complex/cyclosome (APC/C) is an essential ubiquitin ligase that targets cell cycle proteins for proteasome-mediated degradation in mitosis and G1. The APC regulates a number of cell cycle processes, including spindle assembly, mitotic exit, and cytokinesis, but the full range of its functions is still unknown. To better understand cellular pathways controlled by the APC, we performed a proteomic screen to identify additional APC substrates. We analyzed cell cycle–regulated proteins whose expression peaked during the period when other APC substrates were expressed. Subsequent analysis identified several proteins, including the transcriptional repressors Nrm1 and Yhp1, as authentic APC substrates. We found that APCCdh1 targeted Nrm1 and Yhp1 for degradation in early G1 through Destruction-box motifs and that the degradation of these repressors coincided with transcriptional activation of MBF and Mcm1 target genes, respectively. In addition, Nrm1 was stabilized by phosphorylation, most likely by the budding yeast cyclin–dependent protein kinase, Cdc28. We found that expression of stabilized forms of Nrm1 and Yhp1 resulted in reduced cell fitness, due at least in part to incomplete activation of G1-specific genes. Therefore, in addition to its known functions, APC-mediated targeting of Nrm1 and Yhp1 coordinates transcription of multiple genes in G1 with other cell cycle events.

scholarly journals Poly(ADP-Ribose) Polymerase 1 and Ste20-Like Kinase hKFC Act as Transcriptional Repressors for Gamma-2 Herpesvirus Lytic Replication

2003 ◽  
Vol 23 (22) ◽  
pp. 8282-8294 ◽  
Author(s):  
Yousang Gwack ◽  
Hiroyuki Nakamura ◽  
Sun Hwa Lee ◽  
John Souvlis ◽  
Jason T. Yustein ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Lytic Replication ◽  
Lytic Cycle ◽  
Transcriptional Repressors ◽  
Transcription Activator ◽  
Rich Region ◽  
Molecular Sensors ◽  
Genetic Ablation ◽  
Lytic Genes ◽  
Parp 1

ABSTRACT The replication and transcription activator (RTA) of gamma-2 herpesvirus is sufficient to drive the entire virus lytic cycle. Hence, the control of RTA activity should play an important role in the maintenance of viral latency. Here, we demonstrate that cellular poly(ADP-ribose) polymerase 1 (PARP-1) and Ste20-like kinase hKFC interact with the serine/threonine-rich region of gamma-2 herpesvirus RTA and that these interactions efficiently transfer poly(ADP-ribose) and phosphate units to RTA. Consequently, these modifications strongly repressed RTA-mediated transcriptional activation by inhibiting its recruitment onto the promoters of virus lytic genes. Conversely, the genetic ablation of PARP-1 and hKFC interaction or the knockout of the PARP-1 gene and activity considerably enhanced gamma-2 herpesvirus lytic replication. Thus, this is the first demonstration that cellular PARP-1 and hKFC act as molecular sensors to regulate RTA activity and thereby, herpesvirus latency.

scholarly journals Viral-Induced Systemic Necrosis in Plants Involves Both Programmed Cell Death and the Inhibition of Viral Multiplication, Which Are Regulated by Independent Pathways

2010 ◽  
Vol 23 (3) ◽  
pp. 283-293 ◽  
Author(s):  
Ken Komatsu ◽  
Masayoshi Hashimoto ◽  
Johji Ozeki ◽  
Yasuyuki Yamaji ◽  
Kensaku Maejima ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Viral Infection ◽  
Expression Patterns ◽  
Plant Viruses ◽  
Virus Multiplication ◽  
Mitogen Activated Protein Kinase ◽  
Systemic Necrosis ◽  
Viral Multiplication ◽  
Plantago Asiatica

Resistant plants respond rapidly to invading avirulent plant viruses by triggering a hypersensitive response (HR). An HR is accompanied by a restraint of virus multiplication and programmed cell death (PCD), both of which have been observed in systemic necrosis triggered by a successful viral infection. Here, we analyzed signaling pathways underlying the HR in resistance genotype plants and those leading to systemic necrosis. We show that systemic necrosis in Nicotiana benthamiana, induced by Plantago asiatica mosaic virus (PlAMV) infection, was associated with PCD, biochemical features, and gene expression patterns that are characteristic of HR. The induction of necrosis caused by PlAMV infection was dependent on SGT1, RAR1, and the downstream mitogen-activated protein kinase (MAPK) cascade involving MAPKKKα and MEK2. However, although SGT1 and RAR1 silencing led to an increased accumulation of PlAMV, silencing of the MAPKKKα-MEK2 cascade did not. This observation indicates that viral multiplication is partly restrained even in systemic necrosis induced by viral infection, and that this restraint requires SGT1 and RAR1 but not the MAPKKKα-MEK2 cascade. Similarly, although both SGT1 and MAPKKKα were essential for the Rx-mediated HR to Potato virus X (PVX), SGT1 but not MAPKKKα was involved in the restraint of PVX multiplication. These results suggest that systemic necrosis and HR consist of PCD and a restraint of virus multiplication, and that the latter is induced through unknown pathways independent from the former.

scholarly journals Bioinformatic and Physical Characterizations of Genome-Scale Ordered RNA Structure in Mammalian RNA Viruses

2008 ◽  
Vol 82 (23) ◽  
pp. 11824-11836 ◽  
Author(s):  
Matthew Davis ◽  
Selena M. Sagan ◽  
John P. Pezacki ◽  
David J. Evans ◽  
Peter Simmonds
Keyword(s):  
Secondary Structure ◽  
Rna Structure ◽  
Rna Secondary Structure ◽  
Large Scale ◽  
Rna Viruses ◽  
Plant Viruses ◽  
Large Set ◽  
Conserved Sequence ◽  
Evolutionarily Conserved ◽  
Genome Scale

ABSTRACT By the analysis of thermodynamic RNA secondary structure predictions, we previously obtained evidence for evolutionarily conserved large-scale ordering of RNA virus genomes (P. Simmonds, A. Tuplin, and D. J. Evans, RNA 10:1337-1351, 2004). Genome-scale ordered RNA structure (GORS) was widely distributed in many animal and plant viruses, much greater in extent than RNA structures required for viral translation or replication, but in mammalian viruses was associated with host persistence. To substantiate the existence of large-scale RNA structure differences between viruses, a large set of alignments of mammalian RNA viruses and rRNA sequences as controls were examined by thermodynamic methods (to calculate minimum free energy differences) and by algorithmically independent RNAz and Pfold methods. These methods produced generally concordant results and identified substantial differences in the degrees of evolutionarily conserved, sequence order-dependent RNA secondary structure between virus genera and groups. A probe hybridization accessibility assay was used to investigate the physical nature of GORS. Transcripts of hepatitis C virus (HCV), hepatitis G virus/GB virus-C (HGV/GBV-C), and murine norovirus, which are predicted to be structured, were largely inaccessible to hybridization in solution, in contrast to the almost universal binding of probes to a range of unstructured virus transcripts irrespective of G+C content. Using atomic force microscopy, HCV and HGV/GBV-C RNA was visualized as tightly compacted prolate spheroids, while under the same experimental conditions the predicted unstructured poliovirus and rubella virus RNA were pleomorphic and had extensively single-stranded RNA on deposition. Bioinformatic and physical characterization methods both identified fundamental differences in the configurations of viral genomic RNA that may modify their interactions with host cell defenses and their ability to persist.

scholarly journals Mechanisms of Plant Tolerance to RNA Viruses Induced by Plant-Growth-Promoting Microorganisms

Plants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 575 ◽  
Author(s):  
Maksimov I. V ◽  
Sorokan A. V ◽  
Burkhanova G. F ◽  
Veselova S. V ◽  
Alekseev V. Yu ◽  
...  
Keyword(s):  
Viral Infection ◽  
Defense Responses ◽  
Viral Disease ◽  
Plant Viruses ◽  
Plant Tolerance ◽  
Plant Defense Responses ◽  
Higher Plant ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Antiviral Control

Plant viruses are globally responsible for the significant crop losses of economically important plants. All common approaches are not able to eradicate viral infection. Many non-conventional strategies are currently used to control viral infection, but unfortunately, they are not always effective. Therefore, it is necessary to search for efficient and eco-friendly measures to prevent viral diseases. Since the genomic material of 90% higher plant viruses consists of single-stranded RNA, the best way to target the viral genome is to use ribonucleases (RNase), which can be effective against any viral disease of plants. Here, we show the importance of the search for endophytes with protease and RNase activity combined with the capacity to prime antiviral plant defense responses for their protection against viruses. This review discusses the possible mechanisms used to suppress a viral attack as well as the use of local endophytic bacteria for antiviral control in crops.

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