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Minimum internal ribosome entry site required for poliovirus infectivity
A A Haller1, J H Nguyen, B L Semler
1Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine 92717.
Journal of Virology
|December 1, 1993
Summary
This study identifies a minimum internal ribosome entry site (IRES) in poliovirus RNA. This minimum IRES, with deletions, impairs viral protein synthesis and alters viral RNA accumulation.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Internal ribosome entry sites (IRES) mediate cap-independent translation initiation in eukaryotic mRNA.
- Poliovirus mRNA utilizes IRES in its 5' noncoding region for viral protein synthesis.
- Understanding IRES function is crucial for comprehending viral replication strategies.
Purpose of the Study:
- To investigate the functional significance of specific structural elements within the poliovirus IRES.
- To characterize a novel poliovirus mutant with deletions in the IRES region.
- To identify cellular factors interacting with the IRES for translation initiation.
Main Methods:
- Isolation and characterization of a novel poliovirus mutant (Se1-5NC-delta DG) with deletions in the IRES.
- Analysis of viral growth, protein synthesis, and RNA synthesis in infected cells.
- UV cross-linking assays to identify protein-RNA interactions with wild-type and mutant IRES.
Main Results:
- The Se1-5NC-delta DG mutant exhibited slow growth, pinpoint plaques, and delayed protein synthesis.
- Mutant poliovirus mRNA showed defective translation initiation in vitro.
- Viral RNA synthesis kinetics were altered, with accumulation during late infection stages.
- UV cross-linking identified cellular proteins binding to the minimal IRES.
Conclusions:
- The identified deletions create a minimal IRES essential for efficient poliovirus translation.
- The study provides insights into the structure-function relationship of poliovirus IRES.
- Cross-linked cellular proteins are potential key factors in internal translation initiation.