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Geminivirus-encoded TrAP suppressor inhibits the histone methyltransferase SUVH4/KYP to counter host defense.

ABSTRACT: Transcriptional gene silencing (TGS) can serve as an innate immunity against invading DNA viruses throughout Eukaryotes. Geminivirus code for TrAP protein to suppress the TGS pathway. Here we identified an Arabidopsis H3K9me2 histone methyltransferase, Su(var)3-9 homolog 4 (SUVH4/KYP), as a bona fide cellular target of TrAP. TrAP interacts with the catalytic domain of KYP and inhibits its activity in vitro. TrAP elicits developmental anomalies phenocopying several TGS mutants, reduces the repressive H3K9me2 mark and CHH DNA methylation, and reactivates numerous endogenous KYP-repressed loci in vivo. Moreover, KYP binds to the viral chromatin, and controls its methylation to combat virus infection. Notably, kyp mutants support systemic infection of TrAP-deficient Geminivirus. We conclude that TrAP attenuates the TGS of the viral chromatin by inhibiting KYP activity to evade host surveillance. These findings provide new insight on the molecular arms race between host antiviral defense and virus counter defense at an epigenetic level.

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE73586 | GEO | 2015/09/30

SECONDARY ACCESSION(S): PRJNA297369

REPOSITORIES: GEO

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Project description:In susceptible plant hosts, co-evolution has favoured viral strategies to evade host defenses and utilize resources to their own benefit. The degree of manipulation of host gene expression is dependent on host-virus specificity and certain abiotic factors. In order to gain insight into global transcriptomic changes for a geminivirus pathosystem, South African cassava mosaic virus [ZA:99] (SACMV-ZA:99]) and Arabidopsis thaliana, 4 x 44K Agilent microarrays were adopted. After normalization, a 2-fold change filtering of data (p<0.05) identified 1,820 differentially expressed genes in apical leaf tissue. A significant increase in differential gene expression over time (451 genes at 14 dpi, 742 genes at 24 dpi, and 1011 genes at 36 dpi) was observed. This increase in expression, correlated with an increase in SACMV accumulation as virus copies were 5-fold higher at 24 dpi and 6-fold higher at 36 dpi than at 14 dpi (1.1x104 virus copies present at 14 dpi, 5.7x104 copies at 24 dpi, and 6.3x104 copies at 36 dpi). Many 2-fold genes were primarily involved in stress and defense responses, phytohormone signalling pathways, cellular transport, cell-cycle regulation, transcription, oxidation-reduction, and other metabolic processes. Forty-one genes (2.3%) were shown to be continuously expressed across the infection period, indicating that the majority of genes were transient and unique to a particular time point. Plant signalling networks were disrupted and manipulated by SACMV-[ZA:99] in order to affect homeostasis and antagonize hostM-bM-^@M-^Ys defense responses. At the same time, an adaptive response was initiated to reprogramme metabolism and divert energy from growth-related processes to defense, all leading to disruption of normal biological host processes. Comparisons between SACMV-[ZA:99] with plant-infecting RNA and DNA viruses revealed similarities and differences in expression patterns among viruses, showing either general defense or virus-specific responses. Within the Geminiviridae family in particular, similarities in cell-cycle regulation and gene expression patterns correlated between SACMV-[ZA:99] and Cabbage leaf curl virus (CaLCuV) but differences were also evident. For instance, CaLCuV showed antagonistic interactions between Salicyclic Acid (SA) and Jasmonic Acid (JA) pathways, whereas SACMV displayed synergism. Differences in gene induction, repression and outcome between the two geminiviruses clearly demonstrated host-specific interactions with SACMV-[ZA:99] leading to infection. To our knowledge this is the first geminivirus study identifying differentially expressed transcripts across 3 time points A three time-point (14, 24, and 36 dpi) study was carried out to identify differentially expressed genes in SACMV-[ZA:99] infected Arabidopsis leaf cells using a direct comparison design against mock-inoculated controls. Three biological replicates and 1 technical replicate for both SACMV-[ZA:99]-infected and mock-inoculated controls were conducted at each time point.

Project description:In susceptible plant hosts, co-evolution has favoured viral strategies to evade host defenses and utilize resources to their own benefit. The degree of manipulation of host gene expression is dependent on host-virus specificity and certain abiotic factors. In order to gain insight into global transcriptomic changes for a geminivirus pathosystem, South African cassava mosaic virus [ZA:99] (SACMV-ZA:99]) and Arabidopsis thaliana, 4 x 44K Agilent microarrays were adopted. After normalization, a 2-fold change filtering of data (p<0.05) identified 1,820 differentially expressed genes in apical leaf tissue. A significant increase in differential gene expression over time (451 genes at 14 dpi, 742 genes at 24 dpi, and 1011 genes at 36 dpi) was observed. This increase in expression, correlated with an increase in SACMV accumulation as virus copies were 5-fold higher at 24 dpi and 6-fold higher at 36 dpi than at 14 dpi (1.1x104 virus copies present at 14 dpi, 5.7x104 copies at 24 dpi, and 6.3x104 copies at 36 dpi). Many 2-fold genes were primarily involved in stress and defense responses, phytohormone signalling pathways, cellular transport, cell-cycle regulation, transcription, oxidation-reduction, and other metabolic processes. Forty-one genes (2.3%) were shown to be continuously expressed across the infection period, indicating that the majority of genes were transient and unique to a particular time point. Plant signalling networks were disrupted and manipulated by SACMV-[ZA:99] in order to affect homeostasis and antagonize host’s defense responses. At the same time, an adaptive response was initiated to reprogramme metabolism and divert energy from growth-related processes to defense, all leading to disruption of normal biological host processes. Comparisons between SACMV-[ZA:99] with plant-infecting RNA and DNA viruses revealed similarities and differences in expression patterns among viruses, showing either general defense or virus-specific responses. Within the Geminiviridae family in particular, similarities in cell-cycle regulation and gene expression patterns correlated between SACMV-[ZA:99] and Cabbage leaf curl virus (CaLCuV) but differences were also evident. For instance, CaLCuV showed antagonistic interactions between Salicyclic Acid (SA) and Jasmonic Acid (JA) pathways, whereas SACMV displayed synergism. Differences in gene induction, repression and outcome between the two geminiviruses clearly demonstrated host-specific interactions with SACMV-[ZA:99] leading to infection. To our knowledge this is the first geminivirus study identifying differentially expressed transcripts across 3 time points

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Geminivirus-encoded TrAP suppressor inhibits the histone methyltransferase SUVH4/KYP to counter host defense.

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