Processing of the Replicase of Murine Coronavirus: Papain-like Proteinase 2 (PLP2) Acts to Generate p150 and p44

  • Amornrat Kanjanahaluethai
  • Susan C. Baker
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 494)


For Nidoviruses, proteolytic processing of a large polyprotein translated from the 5′-end of the genomic RNA is required for the maturation and assembly of the viral replicase complex. The scheme used to process the arterivirus equine arteritis virus (EAV) replicase polyprotein has been experimentally determined (reviewed in Snijder and Meulenberg, 1998). The EAV replicase polyprotein is processed by 3 distinct proteinases to generate 12 mature protein products. Polyprotein intermediates have been identified as well as major and minor processing pathways. However, the role of the intermediates and the alternate pathways remains to be investigated. For the Coronavirus mouse hepatitis virus (MHV), several laboratories are investigating the pathways used to process the replicase polyprotein. Two major processing models have been postulated and are shown in Figure 1. Studies from our laboratory showed that p150 is an intermediate to the 3C-like Proteinase (3CLpro) product p27 and that p150 likely extends to include the putative membrane-spanning protein domain 1, MPI (Schiller et al 1998). In contrast, other investigators have not detected the p150 precursor and postulate that a p240 product is adjacent to p27 (Denison et al 1992; 1995 and Lu et al 1998). In this study, we developed a specific antiserum to the MPI domain (anti-D11) and determined that the MPI domain is indeed part of the p150 intermediate. Furthermore, we show that MHV papain-like Proteinase 2 (PLP2) is responsible for cleaving the polyprotein at the putative p150 cleavage site. These results show that PLP2 is an active enzyme.


Infectious Bronchitis Virus Proteinase Domain Sindbis Virus Mouse Hepatitis Virus Equine Arteritis Virus 
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  1. Denison, M. R., Hughes, S. A., and Weiss, S. R. 1995. Identification and characterization of a 65-kDa protein processed from the gene 1 polyprotein of the murine Coronavirus MHV-A59. Virology 207:316–320.PubMedCrossRefGoogle Scholar
  2. Denison, M. R., Zoltick, P. W., Hughes, S. A., Giangreco, B., Olson, A. L., Perlman, S., Leibowitz, L. L., and Weiss, S. R. 1992. Intracellular processing of the N-terminal ORF1a proteins of the Coronavirus MHV-A59 requires multiple proteolytic events. Virology 189:274–284.PubMedCrossRefGoogle Scholar
  3. Fuerst, T. R., Niles, E. G., Studier, F. W., and Moss, B. 1986. Eukaryotic transient-expression system based on recombinant vaccinia virus that synthesizes bacteriophage T7 RNA Polymerase. Proc. Natl. Acad. Sci. USA. 83:8122–8126.PubMedCrossRefGoogle Scholar
  4. Gosert, R., Kanjanahaluethai, A., Egger, D., Bienz, K., and Baker, S. C. 2000. Comparison of replicase localization in different types of mouse hepatitis virus (MHV)-infected cells. In The Nidoviruses. (E. Lavi, ed.), Plenum Press, New York (in press).Google Scholar
  5. Kanjanahaluethai, A., and Baker, S. C. 2000. Identification of mouse hepatitis virus papain-like proteinase 2 activity. J. Virol. (in press)Google Scholar
  6. Lemm, J. A., Rumenapf, T., Strauss, E. G., Strauss, J. H., and Rice, C. M. 1994. Polypeptide requirements for assembly of functional Sindbis virus replication complexes: A model for the temporal regulation of minus-and plus-strand RNA synthesis. EMBO J. 13:2925–2934.PubMedGoogle Scholar
  7. Lim, K. P., Ng, L. F. P., and Liu, D. X. 2000. Identification of a novel cleavage activity of the first papain-like proteinase domain encoded by open reading frame 1a of the Coronavirus avian infectious bronchitis virus and characterization of the cleavage products. J. Virol 74:1674–1685.PubMedCrossRefGoogle Scholar
  8. Lu, Y., Sims, A. C., and Denison, M. R. 1998. Mouse hepatitis virus 3C-like protease cleaves a 22-kilodalton protein from the open reading frame 1a polyprotein in virus-infected cells and in vitro. J. Virol. 72:2265–2271PubMedGoogle Scholar
  9. Schiller, J. J., Kanjanahaluethai, A., and Baker, S. C. 1998. Processing of the Coronavirus MHV-JHM polymerase polyprotein: Identification of precursors and proteolytic products spanning 400 kilodaltons of ORFla. Virology 242:288–302.PubMedCrossRefGoogle Scholar
  10. Skirako, Y., and Strauss, J. H. 1994. Regulation of Sindbis virus RNA replication: Uncleaved PI23 and nsP4 function in minus-strand RNA synthesis, whereas cleaved products from P123 are required for efficient plus-strand RNA synthesis. J. Virol. 68:1874–1885.Google Scholar
  11. Snijder, E. J., and Meulenberg, J. J. M. 1998. The molecular biology of arteriviruses. J. Gen. Virol. 79:961–979.PubMedGoogle Scholar
  12. van der Meer, Y., van Tol, H., Locker, J. K., and Snijder, E. J. 1998. ORF la-encoded replicase subunits are involved in the membrane association of the arterivirus replication complex. J. Virol. 72:6689–6698.PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2001

Authors and Affiliations

  • Amornrat Kanjanahaluethai
    • 1
  • Susan C. Baker
    • 1
  1. 1.Department of Microbiology and ImmunologyLoyala University of Chicago, Stritch School of MedicineMaywoodUSA

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