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Coronavirus translational regulation: leader affects mRNA efficiency
S M Tahara1, T A Dietlin, C C Bergmann
1Department of Microbiology, University of Southern California School of Medicine, Los Angeles 90033.
Virology
|August 1, 1994
Summary
Mouse hepatitis virus (MHV) infection stimulates viral protein synthesis. The MHV 5'-leader RNA sequence enhances translation of viral mRNAs in infected cells, not by inhibiting host protein synthesis.
Area of Science:
- Virology
- Molecular Biology
- RNA Biology
Background:
- Murine coronavirus (MHV) infection leads to reduced host protein synthesis and increased viral protein synthesis.
- The mechanisms underlying this shift in protein synthesis during MHV infection are not fully understood.
Purpose of the Study:
- To investigate the role of the conserved MHV 5'-leader RNA sequence in regulating protein synthesis.
- To determine if the viral leader sequence directly enhances viral translation.
Main Methods:
- Constructed chimeric mRNAs with the MHV 5'-leader upstream of the human alpha-globin coding region.
- Translated these constructs in cell-free extracts from uninfected and MHV-infected murine cells.
- Analyzed translation efficiency and sequence specificity.
Main Results:
- The MHV 5'-leader significantly increased translation (3-4 fold) of chimeric mRNAs in infected cell extracts compared to uninfected extracts.
- This enhancement was sequence-specific, as a reversed complementary sequence did not show the same effect.
- A 13-nt region near the start codon was identified as crucial for this increased translation.
Conclusions:
- MHV-infected cells exhibit enhanced viral translation, partly due to the 5'-leader RNA sequence.
- This stimulation occurs in cis and involves a virus-induced factor, rather than solely host translation inhibition.
- The findings provide insight into viral strategies for hijacking host cell machinery.