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SARS-coronavirus replication/transcription complexes are membrane-protected and need a host factor for activity in
Martijn J van Hemert1, Sjoerd H E van den Worm, Kèvin Knoops
1Molecular Virology Laboratory, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands.
Plos Pathogens
|May 3, 2008
Summary
The SARS-coronavirus replication/transcription complex (RTC) requires virus-induced membrane structures for RNA synthesis. This study isolated active RTCs, demonstrating their in vitro RNA synthesis and dependence on membranes for function and protection.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- SARS-coronavirus (SARS-CoV) replication and transcription depend on a replication/transcription complex (RTC).
- The RTC comprises virus-encoded non-structural proteins (nsps) derived from polyproteins.
- RTC is associated with virus-induced double-membrane structures in infected cells.
Purpose of the Study:
- To investigate the link between SARS-CoV-induced membrane structures and viral RNA synthesis.
- To dissect the organization and function of the RTC.
- To develop a robust in vitro assay for RTC activity.
Main Methods:
- Isolation of active RTCs from infected cells.
- Development of an in vitro assay for RTC activity.
- Analysis of RTC components and RNA association with membrane structures.
Main Results:
- The isolated RTC faithfully reproduced genomic RNA and subgenomic mRNA synthesis in vitro.
- RTC activity, nsps, and viral RNA cosedimented with heavy membrane structures.
- RTC activity required a cytoplasmic host factor and was dependent on membranes, which protected viral RNA.
Conclusions:
- SARS-CoV RNA synthesis is critically dependent on virus-induced membrane structures.
- Membranes play a vital role in RTC function, protection, and organization.
- The RTC is a membrane-associated complex essential for viral RNA replication.
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