Making sense of nuclear localization: A zinc-finger protein encoded by a cytoplasmically replicating plant RNA virus acts a transcription factor

Lukhovitskaya, Nina I.; Gushchin, Vladimir A.; Solovyev, A.G.; Savenkov, Eugene I.

doi:10.4161/psb.25263

Cited by 5 publications

(5 citation statements)

References 12 publications

(15 reference statements)

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“…Negative selective pressure is usually interpreted as a mechanism of preserving the structure and function of proteins [70, 104]. The CP of SPCFV and other carlaviruses is multifunctional [104–106], whereas NaBP is a cysteine-rich protein (CRP) implicated in RNA silencing suppression, nuclear localization and viral pathogenesis [68, 107–109]. In NaBP and CP, different codon positions were subjected to varying levels of purifying selection, possibly to provide a balance between the need to maintain protein structure and function and the effectiveness of these functions.…”

Section: Discussionmentioning

confidence: 99%

Mixed Infections of Four Viruses, the Incidence and Phylogenetic Relationships of Sweet Potato Chlorotic Fleck Virus (Betaflexiviridae) Isolates in Wild Species and Sweetpotatoes in Uganda and Evidence of Distinct Isolates in East Africa

2016

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Viruses infecting wild flora may have a significant negative impact on nearby crops, and vice-versa. Only limited information is available on wild species able to host economically important viruses that infect sweetpotatoes (Ipomoea batatas). In this study, Sweet potato chlorotic fleck virus (SPCFV; Carlavirus, Betaflexiviridae) and Sweet potato chlorotic stunt virus (SPCSV; Crinivirus, Closteroviridae) were surveyed in wild plants of family Convolvulaceae (genera Astripomoea, Ipomoea, Hewittia and Lepistemon) in Uganda. Plants belonging to 26 wild species, including annuals, biannuals and perennials from four agro-ecological zones, were observed for virus-like symptoms in 2004 and 2007 and sampled for virus testing. SPCFV was detected in 84 (2.9%) of 2864 plants tested from 17 species. SPCSV was detected in 66 (5.4%) of the 1224 plants from 12 species sampled in 2007. Some SPCSV-infected plants were also infected with Sweet potato feathery mottle virus (SPFMV; Potyvirus, Potyviridae; 1.3%), Sweet potato mild mottle virus (SPMMV; Ipomovirus, Potyviridae; 0.5%) or both (0.4%), but none of these three viruses were detected in SPCFV-infected plants. Co-infection of SPFMV with SPMMV was detected in 1.2% of plants sampled. Virus-like symptoms were observed in 367 wild plants (12.8%), of which 42 plants (11.4%) were negative for the viruses tested. Almost all (92.4%) the 419 sweetpotato plants sampled from fields close to the tested wild plants displayed virus-like symptoms, and 87.1% were infected with one or more of the four viruses. Phylogenetic and evolutionary analyses of the 3′-proximal genomic region of SPCFV, including the silencing suppressor (NaBP)- and coat protein (CP)-coding regions implicated strong purifying selection on the CP and NaBP, and that the SPCFV strains from East Africa are distinguishable from those from other continents. However, the strains from wild species and sweetpotato were indistinguishable, suggesting reciprocal movement of SPCFV between wild and cultivated Convolvulaceae plants in the field.

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Section: Discussionmentioning

confidence: 99%

Mixed Infections of Four Viruses, the Incidence and Phylogenetic Relationships of Sweet Potato Chlorotic Fleck Virus (Betaflexiviridae) Isolates in Wild Species and Sweetpotatoes in Uganda and Evidence of Distinct Isolates in East Africa

2016

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“…Furthermore, CVB p12 was found to act as a genuine transcription factor to upregulate expression of a host gene designated upp-L ( up regulated by p 12). The induction of upp-L requires p12 to enter the nucleus and a specific interaction with the conserved regulatory region in the upp-L promoter involving the p12 zinc-finger domain (Lukhovitskaya et al , 2013b, c). The Upp-L transcription factor, in turn, when ectopically expressed, affects expression of a number of key cell cycle regulators, which results in cell proliferation and severe leaf malformation – a typical phenotypic manifestation of the carlavirus infection (Lukhovitskaya et al , 2013b, c).…”

Section: Full Textmentioning

confidence: 99%

A viral transcription factor exhibits antiviral RNA silencing suppression activity independent of its nuclear localization

Lukhovitskaya

Vetukuri

Sama

et al. 2014

Journal of General Virology

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Viral suppressors of RNA silencing (VSRs) are critical for the success of virus infection and efficient accumulation of virus progeny. The chrysanthemum virus B p12 protein acts as a transcription factor to regulate cell size and proliferation favourable for virus infection. Here, we showed that the p12 protein suppressed RNA silencing and was able to complement a VSRdeficient unrelated virus. Moreover, p12 counter-silencing activity could be uncoupled from its function as a transcription factor in the nucleus. The altered p12 protein, which lacked a nuclear localization signal and was not imported into the nucleus, was able to suppress RNA silencing as efficiently as the native protein. The data revealed new aspects of p12 functioning and identified a novel role for this viral zinc-finger transcription factor. The results provided a general insight into one of the activities of the p12 protein, which appeared to possess more than one function.

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“…The ORF6-11kDa protein contains either a nuclear localization signal made up by a stretch of basic amino acids (R-X4-RKRR-X5-R) [ 39 ] and, immediately downstream of the latter motif, a cysteine-rich signature (C-X2-C-X12-C-X4-C) in the configuration of a C-4 “zinc finger” structure ( Supplementary Materials Figure S1 ). Cysteine-rich proteins (CRP) in carlaviruses are known to act as nucleic acid-binding proteins (NABp) to regulate viral replication, behaving as a silencing suppressor, and are symptom determinants [ 40 , 41 ].…”

Section: Discussionmentioning

confidence: 99%

“…Cysteine-rich proteins (CRP) in carlaviruses are known to act as nucleic acid-binding proteins (NABp) to regulate viral replication, behaving as a silencing suppressor, and are symptom determinants [ 40 , 41 ]. The presence of a nuclear localization signal in the NABp of a virus basically replicating in cytoplasm (like the carlavirus CVB studied by Lukovitskaya et al [ 39 ]) has been associated with the upregulation of a transcription factor ( uppL ) linked to leaf malformation and cell proliferation. This is not the case, however, of JaVC infections so far described in jasmine, where most of the observed symptoms are yellow mosaic and discolorations.…”

Section: Discussionmentioning

confidence: 99%

A New Jasmine Virus C Isolate Identified by Nanopore Sequencing Is Associated to Yellow Mosaic Symptoms of Jasminum officinale in Italy

Amoia

Minafra

Nicoloso

et al. 2022

Plants

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Some plants of Jasminum officinale were selected in a nursery for investigation of sanitary status of candidate mother plants before vegetative propagation. The presence of yellow spots and leaf discoloration symptoms pushed for a generic diagnosis through deep sequencing to discover systemic pathogens. Either dsRNA or total RNA were extracted and used in nanopore and Illumina platform for cDNA-PCR, direct RNA and total RNA rRNA-depleted sequencing. A few single reads obtained by nanopore technology or assembled contigs gave unequivocal annotation for the only presence of a jasmine virus C (JaVC, a putative member of genus Carlavirus) isolate. The full-length genome of this isolate was reconstructed, spanning 8490 nucleotides (nt). This isolate shared 90.9% similarity with coat protein sequences and 84% with the entire ORF1 polyprotein, with the other two available JaVC full genomes, isolated from infections in J. sambac in Taiwan and China. The overall nucleotide identity shared by the newly discovered Italian isolate with the Chinese JaVC full genomes was 76.14% (Taiwan) and 75.60% (Fujian). The application of quick nanopore sequencing for virus discovery was assessed. The identification of the virus in a new ornamental host species, largely used in gardening, creates a concern for the potential virus spread and need of testing for production of clean vegetative material.

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Making sense of nuclear localization: A zinc-finger protein encoded by a cytoplasmically replicating plant RNA virus acts a transcription factor

Cited by 5 publications

References 12 publications

Mixed Infections of Four Viruses, the Incidence and Phylogenetic Relationships of Sweet Potato Chlorotic Fleck Virus (Betaflexiviridae) Isolates in Wild Species and Sweetpotatoes in Uganda and Evidence of Distinct Isolates in East Africa

Mixed Infections of Four Viruses, the Incidence and Phylogenetic Relationships of Sweet Potato Chlorotic Fleck Virus (Betaflexiviridae) Isolates in Wild Species and Sweetpotatoes in Uganda and Evidence of Distinct Isolates in East Africa

A viral transcription factor exhibits antiviral RNA silencing suppression activity independent of its nuclear localization

A New Jasmine Virus C Isolate Identified by Nanopore Sequencing Is Associated to Yellow Mosaic Symptoms of Jasminum officinale in Italy

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