This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Lulla, V.
Right arrow Articles by Ahola, T.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Lulla, V.
Right arrow Articles by Ahola, T.

 Previous Article  |  Next Article 

Journal of Virology, September 2008, p. 9236-9244, Vol. 82, No. 18
0022-538X/08/$08.00+0     doi:10.1128/JVI.00711-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Molecular Defects Caused by Temperature-Sensitive Mutations in Semliki Forest Virus nsP1{triangledown}

Valeria Lulla,1,2 Dorothea L. Sawicki,3 Stanley G. Sawicki,3 Aleksei Lulla,1 Andres Merits,1 and Tero Ahola2*

Institute of Technology, University of Tartu, Tartu, Estonia,1 Program in Cellular Biotechnology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland,2 Microbiology and Immunology Department, College of Medicine, University of Toledo, Toledo, Ohio3

Received 31 March 2008/ Accepted 28 June 2008

Alphavirus replicase protein nsP1 has multiple functions during viral RNA synthesis. It catalyzes methyltransferase and guanylyltransferase activities needed in viral mRNA capping, attaches the viral replication complex to cytoplasmic membranes, and is required for minus-strand RNA synthesis. Two temperature-sensitive (ts) mutations in Semliki Forest virus (SFV) were previously identified within nsP1: ts10 (E529D) and ts14 (D119N). Recombinant viruses containing these individual mutations reproduced the features of the original ts strains. We now find that the capping-associated enzymatic activities of recombinant nsP1, containing ts10 or ts14 lesions, were not ts. The mutant proteins and polyproteins also were membrane bound, mutant nsP1 interacted normally with the other nonstructural proteins, and there was no major defect in nonstructural polyprotein processing in the mutants, although ts14 surprisingly displayed slightly retarded processing. The two mutant viruses were specifically defective in minus-strand RNA synthesis at the restrictive temperature. Integrating data from SFV and Sindbis virus, we discuss the domain structure of nsP1 and the relative positioning of and interactions between the replicase proteins. nsP1 is suggested to contain a specific subdomain involved in minus-strand synthesis and interaction with the polymerase nsP4 and the protease nsP2.

* Corresponding author. Mailing address: Institute of Biotechnology, P.O. Box 56, University of Helsinki, FIN-00014 Helsinki, Finland. Phone: 358-9-19159403. Fax: 358-9-19159560. E-mail: tero.ahola{at}helsinki.fi

{triangledown} Published ahead of print on 2 July 2008.

Journal of Virology, September 2008, p. 9236-9244, Vol. 82, No. 18
0022-538X/08/$08.00+0     doi:10.1128/JVI.00711-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Mai, J., Sawicki, S. G., Sawicki, D. L. (2009). Fate of Minus-Strand Templates and Replication Complexes Produced by a P23-Cleavage-Defective Mutant of Sindbis Virus. J. Virol. 83: 8553-8564 [Abstract] [Full Text]  


Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»