Related Experiment Video
Updated: Jun 14, 2026

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase
Published on: April 29, 2010
Primer-independent initiation of RNA synthesis by SeMV recombinant RNA-dependent RNA polymerase
1Indian Institute of Science, Bangalore 560012, Karnataka, India.
Abstract:
Sesbania mosaic virus (SeMV), a single-strand positive-sense RNA plant virus, belongs to the genus Sobemoviruses. Mechanism of replication in Sobemoviruses is poorly understood. In the present study, SeMV RNA-dependent RNA polymerase (RdRp) was overexpressed and purified as a thioredoxin-tagged protein. The recombinant SeMV RdRp could synthesize RNA from genomic or subgenomic RNA templates, even in the absence of the protein primer, VPg. Analysis of the product indicated that it was double-stranded and that the mode of initiation was de novo. Mutational analysis of the 3' UTR of subgenomic RNA revealed that a stem-loop structure at the 3' end was important. Further, analysis of this stem-loop showed that the SeMV RdRp was capable of recognizing stem-loop structures of various lengths and forms. These results demonstrate that the SeMV RdRp is capable of primer-independent RNA synthesis in vitro.
Related Concept Videos
Bacterial Transcription
Transcription can be divided into three main stages, each involving distinct DNA sequences to guide the polymerase. These are:
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Bacterial RNA Polymerase
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...
Transcription Initiation
The promoters and enhancers and their accessory proteins allow tight regulation of...
Initiation of Translation
First, the initiator tRNA must be selected from the pool of elongator tRNAs by eukaryotic initiation factor 2 (eIF2). The initiator tRNA (Met-tRNAi) has conserved sequence elements including modified bases at...
Eukaryotic RNA Polymerases
All three eukaryotic RNAPs require specific transcription factors, of which the...

