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Coronaviruses pp 215-219 | Cite as

Altered Proteolytic Processing of the Polymerase Polyprotein in RNA(-) Temperature Sensitive Mutants of Murine Coronavirus

  • Susan C. Baker
  • HongQiang Gao
  • Ralph S. Baric
Chapter
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Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 342)

Abstract

We examined the synthesis and processing of the polymerase polyprotein in RNA(-) temperature sensitive mutant of murine coronavirus strain A59. These temperature sensitive mutants of MHV-A59 synthesize viral RNA at the permissive temperature (33.0°C), but are unable to synthesize viral RNA at the nonpermissive temperature (39.5°C). The is mutants have been mapped to five different complementation groups in the polymerase gene. The 5’-most complementation groups, Groups A and B map to a region encoding an autoproteinase responsible for the cleavage of p28, the amino-terminal product of the polymerase polyprotein. We screened six temperature sensitive mutants to determine if there was an alteration in the proteolytic processing of the polymerase polyprotein, particularly in the cleavage of the p28 protein. Two mutants, tsNC9 and tsLA16, had altered proteolytic products at both the permissive and nonpermissive temperatures. One Group B temperature sensitive mutant, designated tsNC11, was defective in the production of p28 protein at the nonpermissive temperature. To further localize the site of the mutation in tsNCl1, RNA representing the 5’-most 5.3 kb region of the polymerase gene was transfected into tsNCllinfected cells and virus production monitored. The transfected RNA was able to complement the defect in tsNC11, resulting in viral RNA synthesis and production of viral particles at the nonpermissive temperature. These results indicate that a gene product from the 5.3 kb region of gene 1 is required for coronavirus RNA synthesis.

Keywords

Polymerase Gene Complementation Group Temperature Sensitive Mutant Nonpermissive Temperature Proteolytic Product 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1994

Authors and Affiliations

  • Susan C. Baker
    • 1
  • HongQiang Gao
    • 1
  • Ralph S. Baric
    • 2
  1. 1.Department of Microbiology and ImmunologyLoyola University Medical CenterMaywoodUSA
  2. 2.Department of EpidemiologyUniversity of North Carolina at Chapel HillChapel HillUSA

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