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Characterization of the protease of a fish retrovirus, walleye dermal sarcoma virus.

ABSTRACT: Three fish retroviruses infecting walleyes constitute the recently recognized genus called epsilonretrovirus. The founding member of this group, walleye dermal sarcoma virus (WDSV), induces benign skin tumors in the infected fish and replicates near 4 degrees C. While the viral genomic sequence is known, biochemical characterization of the virus has been limited to the identification of the mature structural and envelope proteins present in virions. We undertook this study to determine the cleavage sites in the WDSV Pro and Pol proteins and to characterize the viral protease (PR) in vitro. A recombinant PR was expressed in and purified from Escherichia coli as a larger fusion with additional nucleocapsid and reverse transcriptase residues flanking the PR domain. Autocleavage produced a functional, mature PR. Autocleavage as well as cleavage of peptides and of Gag protein by the mature PR occurred at a pH optimum of 7.0, higher than that of other retroviral proteases. Analysis of the cleavage sites identified a glutamine residue in the P2 position of all WDSV sites, both in Gag and in Pol. Amino acid sequence alignments of Gag-Pro-Pol from WDSV, walleye epidermal hyperplasia virus type 1, and walleye epidermal hyperplasia virus type 2 showed the P2 glutamine to be conserved in all cleavage sites in these three viruses. Such conservation is unprecedented in other retroviruses.

SUBMITTER: Fodor SK

PROVIDER: S-EPMC155057 | biostudies-literature | 2002 May

REPOSITORIES: biostudies-literature

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Characterization of the protease of a fish retrovirus, walleye dermal sarcoma virus.

Fodor Sharon K SK Vogt Volker M VM

Journal of virology 20020501 9

Three fish retroviruses infecting walleyes constitute the recently recognized genus called epsilonretrovirus. The founding member of this group, walleye dermal sarcoma virus (WDSV), induces benign skin tumors in the infected fish and replicates near 4 degrees C. While the viral genomic sequence is known, biochemical characterization of the virus has been limited to the identification of the mature structural and envelope proteins present in virions. We undertook this study to determine the cleav ...[more]

PMID: 11932400

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Project description:Walleye epidermal hyperplasia virus types 1 and 2 (WEHV1 and WEHV2, respectively) are associated with a hyperproliferative skin lesion on walleyes that appears and regresses seasonally. We have determined the complete nucleotide sequences and transcriptional profiles of these viruses. WEHV1 and WEHV2 are large, complex retroviruses of 12,999 and 13,125 kb in length, respectively, that are closely related to one another and to walleye dermal sarcoma virus (WDSV). These walleye retroviruses contain three open reading frames, orfA, orfB, and orfC, in addition to gag, pol, and env. orfA and orfB are adjacent to one another and located downstream of env. The OrfA proteins were previously identified as cyclin D homologs that may contribute to the induction of cell proliferation leading to epidermal hyperplasia and dermal sarcoma. The sequence analysis of WEHV1 and WEHV2 revealed that the OrfB proteins are distantly related to the OrfA proteins, suggesting that orfB arose by gene duplication. Presuming that the precursor of orfA and orfB was derived from a cellular cyclin, these genes are the first accessory genes of complex retroviruses that can be traced to a cellular origin. WEHV1, WEHV2, and WDSV are the only retroviruses that have an open reading frame, orfC, of considerable size (ca. 130 amino acids) in the leader region preceding gag. While we were unable to predict a function for the OrfC proteins, they are more conserved than OrfA and OrfB, suggesting that they may be biologically important to the viruses. The transcriptional profiles of WEHV1 and WEHV2 were also similar to that of WDSV; Northern blot analyses detected only low levels of the orfA transcripts in developing lesions, whereas abundant levels of genomic, env, orfA, and orfB transcripts were detected in regressing lesions. The splice donors and acceptors of individual transcripts were identified by reverse transcriptase PCR. The similarities of WEHV1, WEHV2, and WDSV suggest that these viruses use similar strategies of viral replication and induce cell proliferation by a similar mechanism.

Dataset Information

Characterization of the protease of a fish retrovirus, walleye dermal sarcoma virus.

Publications

Characterization of the protease of a fish retrovirus, walleye dermal sarcoma virus.

Similar Datasets

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