Transcriptional analysis of a major capsid protein gene from Spodoptera exigua ascovirus 5a

Salem, Tamer Z.; Turney, Colin M.; Wang, L.; Xue, Jianli; Wan, Xiu‐Feng; Cheng, Xiao Wen

doi:10.1007/s00705-007-1081-3

Cited by 12 publications

(11 citation statements)

References 37 publications

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“…Interestingly, many of the messages were missing a poly(A) signal near the 3= end, with RNA secondary structures, in these cases, observed in some messages. Involvement of stem-loop structure in transcription termination has been reported before for the major capsid protein of Spodoptera exigua ascovirus 5a (SeAV-5a) (18).…”

Section: In Vivo Expression Of Sfav Genesmentioning

confidence: 63%

“…5). We were able to detect the previously identified late consensus sequences TATA box-like motif (TAATTAAA) and ATTTGATCTT in two late genes, namely, ORF22 (RNase III) and ORF41 (MCP), respectively (18,19). The TATA box like motif is located 16 bp before the ATG start codon, and the ATTTGATCTT consensus sequence is 28 bp before the ORF start codon.…”

Section: In Vivo Expression Of Sfav Genesmentioning

confidence: 86%

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Transcriptome Analysis of the Spodoptera frugiperda AscovirusIn VivoProvides Insights into How Its Apoptosis Inhibitors and Caspase Promote Increased Synthesis of Viral Vesicles and Virion Progeny

Zaghloul

Hice

Arensburger

et al. 2017

J Virol

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Ascoviruses are ds DNA viruses that attack caterpillars and differ from all other viruses by inducing nuclear lysis followed by cleavage of host cells into numerous anucleate vesicles in which virus replication continues as these grow in the blood. Ascoviruses are also unusual in that most encode apoptosis inhibitors and caspase or caspase-like proteins. A robust cell line to study the novel molecular biology of ascovirus replication is lacking. Therefore, we used strand-specific RNA-Seq to study transcription in third instars of infected with the Spodoptera frugiperda ascovirus, a member of the type species, (SfAV-1a), sampling transcripts at different time points after infection. We targeted transcription of two types of SfAV-1a genes; first, 44 core genes that occur in several ascovirus species, and second, 26 genes predicted to have metabolic functions likely involved in synthesizing viral vesicle membranes. Gene cluster analysis showed differences in temporal expression of SfAV-1a genes, enabling their assignment to three temporal classes; early, late and very late. Inhibitors of apoptosis (IAP-like proteins; ORF016, ORF025 and ORF074) were expressed early, whereas its caspase (ORF073) was expressed very late, which correlated with apoptotic events leading to viral vesicle formation. Expression analysis revealed that a Diedel gene homolog (ORF121), the only known "virokine," was highly expressed, implying this ascovirus protein helps evade innate host immunity. Lastly, single-nucleotide resolution of RNA-Seq data revealed 15 bicistronic and tricistronic messages along the genome, an unusual occurrence for large ds DNA viruses. Unlike all other DNA viruses, ascoviruses code for an executioner caspase, apparently involved in a novel cytopathology in which viral replication induces nuclear lysis followed by cell cleavage yielding numerous large anucleate viral vesicles that continue to produce virions. Our transcriptome analysis of genome expression by the Spodoptera frugiperda ascovirus shows that inhibitors of apoptosis are expressed first enabling viral replication to proceed, after which the SfAV-1a caspase is synthesized, leading to viral vesicle synthesis and subsequent extensive production of progeny virions. Moreover, we detected numerous bicistronic and tricistronic mRNA messages in the ascovirus transcriptome, implying ascoviruses use other non-canonical translational mechanisms such as Internal Ribosome Entry Site (IRES). These results provide the first insights into the molecular biology of a unique coordinated gene expression pattern in which cell architecture is markedly modified, more than in any other known eukaryotic virus, to promote viral reproduction and transmission.

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Section: In Vivo Expression Of Sfav Genesmentioning

confidence: 63%

Section: In Vivo Expression Of Sfav Genesmentioning

confidence: 86%

Transcriptome Analysis of the Spodoptera frugiperda AscovirusIn VivoProvides Insights into How Its Apoptosis Inhibitors and Caspase Promote Increased Synthesis of Viral Vesicles and Virion Progeny

Zaghloul

Hice

Arensburger

et al. 2017

J Virol

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“…The current knowledge about transcription in ascoviruses come from the analyses of the Ascovirus genus [ 110 , 113 ]. A study performed using a possible variant of HvAV-3, the Spodoptera exigua ascovirus 5a (SeAV-5a) showed that the 5’-UTR region of the SeAV-5a MCP gene is composed of 25-nt [ 114 ]. The upstream region of this gene does not present a typical eukaryotic class II promoter motif sequence ‘TATAAAT’ (TATA box).…”

Section: Ascoviridaementioning

confidence: 99%

“…The upstream region of this gene does not present a typical eukaryotic class II promoter motif sequence ‘TATAAAT’ (TATA box). However, the putative 5’ transcription control region of the SeAV-5a MCP gene shares similarities with other ascoviruses and iridoviruses, containing a conserved TATA-box like motif (TAATTAAA) and an ‘ATTTGATCTT’ motif within 40-nt upstream of the translation initiation codon ATG [ 114 ]. The ‘TAATTAAA’ and ‘ATTTGATCTT’ motifs are located downstream and upstream of the transcription initiation site, respectively.…”

Section: Ascoviridaementioning

confidence: 99%

Promoter Motifs in NCLDVs: An Evolutionary Perspective

Oliveira

Andrade

Rodrigues

et al. 2017

Viruses

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For many years, gene expression in the three cellular domains has been studied in an attempt to discover sequences associated with the regulation of the transcription process. Some specific transcriptional features were described in viruses, although few studies have been devoted to understanding the evolutionary aspects related to the spread of promoter motifs through related viral families. The discovery of giant viruses and the proposition of the new viral order Megavirales that comprise a monophyletic group, named nucleo-cytoplasmic large DNA viruses (NCLDV), raised new questions in the field. Some putative promoter sequences have already been described for some NCLDV members, bringing new insights into the evolutionary history of these complex microorganisms. In this review, we summarize the main aspects of the transcription regulation process in the three domains of life, followed by a systematic description of what is currently known about promoter regions in several NCLDVs. We also discuss how the analysis of the promoter sequences could bring new ideas about the giant viruses’ evolution. Finally, considering a possible common ancestor for the NCLDV group, we discussed possible promoters’ evolutionary scenarios and propose the term “MEGA-box” to designate an ancestor promoter motif (‘TATATAAAATTGA’) that could be evolved gradually by nucleotides’ gain and loss and point mutations.

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“…Some studies have described putative A/T-rich promoter sequences for nucleocytoplasmic large DNA viruses (NCLDV) from different families (15)(16)(17)(18)(19)(20)(21). In 2005, the mimivirus promoter sequence was identified.…”

mentioning

confidence: 99%

The Investigation of Promoter Sequences of Marseilleviruses Highlights a Remarkable Abundance of the AAATATTT Motif in Intergenic Regions

Oliveira

Lima

Arantes

et al. 2017

J Virol

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Viruses display a wide range of genomic profiles and, consequently, a variety of gene expression strategies. Specific sequences associated with transcriptional processes have been described in viruses, and putative promoter motifs have been elucidated for some nucleocytoplasmic large DNA viruses (NCLDV). Among NCLDV, the is a well-recognized family because of its genomic mosaicism. The marseilleviruses have an ability to incorporate foreign genes, especially from sympatric organisms inhabiting, its main known host. Here, we identified for the first time an eight-nucleotide A/T-rich promoter sequence (AAATATTT) associated with 55% of marseillevirus genes that is conserved in all marseilleviruses lineages, a higher level of conservation than that of any giant virus described to date. We instigated our prediction about the promoter motif by biological assays and by evaluating how single mutations in this octamer can impact gene expression. The investigation of sequences that regulate the expression of genes relative to lateral transfer revealed that the promoter motifs do not appear to be incorporated by marseilleviruses from donor organisms. Indeed, analyses of the intergenic regions that regulate lateral gene transfer-related genes have revealed an independent origin of the marseillevirus intergenic regions that does not match gene-donor organisms. About 50% of AAATATTT motifs spread throughout intergenic regions of the marseilleviruses are present as multiple copies. We believe that such multiple motifs are associated with increased expression of a given gene or are related to incorporation of foreign genes into the mosaic genome of marseilleviruses. The marseilleviruses draw attention because of the peculiar features of their genomes; however, little is known about their gene expression patterns or the factors that regulate those expression patterns. The limited published research on the expression patterns of the marseilleviruses and their unique genomes has led us to study the promoter motif sequences in the intergenic regions of the marseilleviruses. This work is the first to analyze promoter sequences in the genomes of the marseilleviruses. We also suggest a strong capacity to acquire foreign genes and to express those genes mediated by multiple copies of the promoter motifs available in intergenic regions. These findings contribute to an understanding of genomic expansion and plasticity observed in these giant viruses.

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Transcriptional analysis of a major capsid protein gene from Spodoptera exigua ascovirus 5a

Cited by 12 publications

References 37 publications

Transcriptome Analysis of the Spodoptera frugiperda AscovirusIn VivoProvides Insights into How Its Apoptosis Inhibitors and Caspase Promote Increased Synthesis of Viral Vesicles and Virion Progeny

Transcriptome Analysis of the Spodoptera frugiperda AscovirusIn VivoProvides Insights into How Its Apoptosis Inhibitors and Caspase Promote Increased Synthesis of Viral Vesicles and Virion Progeny

Promoter Motifs in NCLDVs: An Evolutionary Perspective

The Investigation of Promoter Sequences of Marseilleviruses Highlights a Remarkable Abundance of the AAATATTT Motif in Intergenic Regions

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