Geminivirus Rep protein interferes with the plant DNA methylation machinery and suppresses transcriptional gene silencing

Edgar Rodríguez-Negrete, Rosa Lozano-Durán, Alvaro Piedra-Aguilera, Lucia Cruzado, Eduardo R. Bejarano, Araceli G. Castillo

Research output: Contribution to journalArticlepeer-review

139 Scopus citations

Abstract

Cytosine methylation is an epigenetic mark that promotes gene silencing and plays an important role in genome defence against transposons and invading DNA viruses. Previous data showed that the largest family of single-stranded DNA viruses, Geminiviridae, prevents methylation-mediated transcriptional gene silencing (TGS) by interfering with the proper functioning of the plant methylation cycle. Here, we describe a novel counter-defence strategy used by geminiviruses, which reduces the expression of the plant maintenance DNA methyltransferases, METHYLTRANSFERASE 1 (MET1) and CHROMOMETHYLASE 3 (CMT3), in both locally and systemically infected tissues. We demonstrated that the virus-mediated repression of these two maintenance DNA methyltransferases is widespread among geminivirus species. Additionally, we identified Rep (Replication associated protein) as the geminiviral protein responsible for the repression of MET1 and CMT3, and another viral protein, C4, as an ancillary player in MET1 down-regulation. The presence of Rep suppressed TGS of an Arabidopsis thaliana transgene and of host loci whose expression was strongly controlled by CG methylation. Bisulfite sequencing analyses showed that the expression of Rep caused a substantial reduction in the levels of DNA methylation at CG sites. Our findings suggest that Rep, the only viral protein essential for replication, displays TGS suppressor activity through a mechanism distinct from that thus far described for geminiviruses.

Original languageEnglish
Pages (from-to)464-475
Number of pages12
JournalNew Phytologist
Volume199
Issue number2
DOIs
StatePublished - Jul 2013
Externally publishedYes

Keywords

  • C4
  • CHROMOMETHYLASE3
  • DNA methylation
  • Geminivirus
  • Gene silencing
  • METHYLTRANSFERASE1
  • Rep
  • Transcriptional gene silencing suppressor

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