Translational products encoded by newly acquired sequences of independently derived feline sarcoma virus isolates are structurally related

Abstract

Polyproteins encoded by several independent isolates of feline sarcoma virus (FeSV) were analyzed with respect to molecular weight, extent of phosphorylation, and tryptic peptide composition. As previously reported, cells nonproductively transformed by the Gardner strain of FeSV express a polyprotein which has a molecular weight of approximately 115,000 and contains feline leukemia virus p15, p12, and minor portion of p30. In addition, a major 72,000-dalton possible cleavage product can be identified. Snyder-Theilen FeSV-transformed cells express a major polyprotein of approximately 115,000 daltons and a second highly related 80,000-dalton protein. The p12 structural component of Gardner FeSV P115, but not Snyder-Theilen FeSV 115, corresponds to feline leukemia virus subgroup A with respect to immunological type specificity, a finding consistent with the independent origin of these viruses. Tryptic peptide analysis revealed five methionine-containing peptides specific to the nonstructural portion of Gardner FeSV 115, three of which were also represented in Snyder-Theilen FeSV P115, three of which were also represented in Snyder-Theilen FeSV P115. None of these [35S]methionine-labeled tryptic peptides were present in translational products representative of the complete feline leukemia virus subgroup A genome, including Pr180gag-pol, Pr65gag, and Pr82env. Similarly phosphorylated tryptic peptides within the structural (p12) and nonstructural components of Gardner FeSV P115 and Snyder-Theilen FeSV P115 Are highly related. These findings support the possibility that acquired sequences of two independently derived isolates of FeSV encode structurally related proteins.

Anemia- and polycythemia-inducing isolates of Friend spleen focus-forming virus. Biological and molecular evidence for two distinct viral genomes.

“…Exponentially growing cells Were labeled with [ S]methionine (1,075 Ci/mmol, Amersham Corp., Arlington Heights, I11.) as previously described (21). After labeling, cell monolayers were washed twice with serum-free medium and disrupted at 4°C in 10 mM sodium phosphate, pH 7.2, 0.9% NaCI, 1% Triton X-100, 0.5% sodium deoxycholate, and 0.1% SDS (PBSTDS) lysis buffer.…”

Involvement of a high-molecular-weight polyprotein translational product of Snyder-Theilen Feline sarcoma virus in malignant transformation

“…Each, in the presence of an appropriate type C helper virus, transforms embryo fibroblasts in cell culture and induces fibrosarcomas in vivo. The two isolates studied in greatest detail, Gardner and Snyder-Theilen, encode as their major translational products polyproteins of around 115,000 molecular weight (Mr) (10,26,30). In addition, cells transformed by these isolates exhibit possible cleavage products of 72,000 and 80,000 Mr, respectively (30).…”

Differences in mechanisms of transformation by independent feline sarcoma virus isolates

“…Three independently derived recombinant type C virus isolates of feline origin have been shown to induce fibrosarcomas in vivo and to transform embryo fibroblasts in cell culture (10,14,24). The major translational products of such isolates are in each case high-molecular-weight (>100,000) polyproteins consisting of type C virus structural and acquired sequence-encoded components (2, 12,21,25,30,31). In the case of one of these isolates, Snyder-Theilen feline sarcoma virus (FeSV), two variants have been reported, one encoding a major polyprotein of 115,000 Mr (30) and the second encoding an 85,000Mr polyprotein (2, 16,21).…”

“…In the case of one of these isolates, Snyder-Theilen feline sarcoma virus (FeSV), two variants have been reported, one encoding a major polyprotein of 115,000 Mr (30) and the second encoding an 85,000Mr polyprotein (2, 16,21). McDonough FeSV and Gardner FeSV encode as their major translational products polyproteins of 170,000 Mr (2, 31) and 115,000 Mr (25,30), respectively. Protein kinase activities with specificity for tyrosine residues closely associated with, or intrinsic to, the Gardner and Snyder-Theilen FeSVencoded polyproteins have been identified and shown to recognize the polyproteins themselves as substrates (1, 18, 32).…”