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Published on: September 7, 2017
Conformation-selective methylation of geminivirus DNA.
T Paprotka1, K Deuschle, V Metzler
1Biologisches Institut, Abteilung für Molekularbiologie und Virologie der Pflanzen, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany.
Journal of Virology
|August 13, 2011
Summary
Geminiviruses (plant viruses) show minimal DNA methylation, with only a specific promoter region being protected. Methylation-cytosine specific antibodies only detected methylation in heterogeneous linear DNA, suggesting efficient evasion of silencing.
Area of Science:
- Plant virology
- Molecular biology
- Epigenetics
Background:
- Geminiviruses possess small, single-stranded DNA genomes and replicate via double-stranded DNA (dsDNA) intermediates.
- Previous studies indicated potential partial cytosine methylation in geminivirus DNA.
- Understanding methylation patterns is crucial for deciphering viral replication and host interactions.
Purpose of the Study:
- To investigate the methylation patterns of circular and linear dsDNA intermediates of geminiviruses.
- To determine if geminiviruses utilize DNA methylation to evade host silencing mechanisms.
Main Methods:
- Bisulfite treatment followed by rolling circle amplification and shotgun sequencing.
- Analysis of cytosine maintenance rates post-bisulfite treatment.
- Use of methylation-sensitive restriction enzymes.
- Detection using methylcytosine-specific antibodies.
Main Results:
- A uniform, low rate of cytosine maintenance (around 50%) was observed for both circular viral DNA and control bacteriophage DNA, indicating minimal methylation.
- A specific region within the C2/C3 promoter of tomato yellow leaf curl Sardinia virus (TYLCSV) showed a statistically significant higher protection rate.
- Methylcytosine-specific antibodies and methylation-dependent restriction enzymes detected methylation predominantly in heterogeneous linear dsDNA forms, not circular forms.
Conclusions:
- Geminiviruses exhibit highly efficient evasion of host silencing, likely through mechanisms other than widespread DNA methylation of circular forms.
- While circular viral DNA appears largely unmethylated, linear dsDNA intermediates may undergo preferential methylation.
- The findings suggest a complex interplay between geminivirus replication, DNA forms, and host epigenetic defenses.
