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Splicing features in maize streak virus virion- and complementary-sense gene expression
E A Wright1, T Heckel, J Groenendijk
1Department of Virus Research, John Innes Centre, Norwich Research Park, Colney, UK.
The Plant Journal : for Cell and Molecular Biology
|February 5, 1998
Summary
Maize streak virus (MSV) utilizes alternative splicing to regulate gene expression from both DNA strands. Splicing of complementary-sense transcripts is essential for virus replication, while virion-sense transcript splicing impacts gene expression.
Area of Science:
- Plant virology
- Molecular biology
- Gene expression regulation
Background:
- Geminiviruses are single-stranded DNA viruses that infect plants.
- Maize streak virus (MSV) replicates its DNA in the nucleus and produces transcripts from both DNA strands.
- Differential splicing of viral transcripts is a known regulatory mechanism in some viruses.
Purpose of the Study:
- To investigate the role of alternative splicing in the gene expression of Maize Streak Virus (MSV).
- To characterize the spliced and unspliced transcripts produced by MSV and Digitaria streak virus (DSV).
- To determine the importance of specific splice sites for viral replication and gene expression.
Main Methods:
- Analysis of complementary-sense and virion-sense transcripts in MSV-infected maize.
- Identification and characterization of introns and splice sites within MSV genes.
- Mutagenesis studies to assess the impact of splice site disruption on viral replication.
- Comparative analysis of transcript splicing in MSV, DSV, and wheat dwarf virus.
Main Results:
- Complementary-sense transcripts are either translated directly to produce the C1 protein or spliced to form a C1:C2 fusion protein (Rep), with splicing being essential for replication.
- Virion-sense transcripts initiate from multiple sites and undergo differential splicing, with varying efficiencies for major and minor transcripts.
- Mutagenesis of the V1 gene's 5' splice site leads to the use of cryptic splice sites, highlighting splicing's importance.
- Spliced virion-sense transcripts are found in MSV and DSV infections but not in wheat dwarf virus infections.
Conclusions:
- Alternative splicing plays a crucial role in regulating both early and late gene expression in MSV and DSV.
- The efficiency of splicing and the use of alternative splice sites are critical for geminivirus infection.
- Differential splicing mechanisms contribute to the diversity of viral gene products and infection strategies.