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Virology. 1993 Mar;193(1):403-13.

In vitro guanylylation of infectious pancreatic necrosis virus polypeptide VP1.

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Department of Microbiology, College of Biological Sciences, University of Guelph, Ontario, Canada.


Incubation of purified infectious pancreatic necrosis virus (IPNV) in the presence of [alpha 32P]GTP resulted in the formation of VP1-GMP. The GMP is linked to VP1 by a phosphodiester bond and its formation does not require the presence of divalent cations. In contrast to reovirus guanylyl transferase, the formation of IPNV VP1-GMP is not reversible and the guanylylation reaction is not inhibited by inorganic pyrophosphate. Furthermore, the IPNV VP1-GMP cannot transfer the GMP to an acceptor molecule (such as GTP) indicating that VP1 is not a capping enzyme. Time-course experiments revealed that after the initial guanylylation of VP1 to form VP1-pG, a second GMP is added to form VP1-pGpG, the formation of which is template-dependent. Since VP1 is present in the virion both as a free polypeptide and in a genome-linked form as VPg, and it is also the virion-associated RNA polymerase, the results suggest that VP1 may function as a primer during in vitro RNA synthesis.

[Indexed for MEDLINE]

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