Molecular Cloning of the Fujinami Sarcoma Virus Genome and Its Comparison with Sequences of Other Related Transforming Viruses

Masabumi Shibuya, Lu-Hai Wang, Hidesaburo Hanafusa
1982 Journal of Virology  
Full-length proviral DNA of Fujinami sarcoma virus (FSV) of chickens was molecularly cloned and characterized. An analysis of FSV DNA integrated in mammalian cells showed that restriction endonuclease Sacl has a single cleavage site on FSV DNA. Unintegrated closed circular FSV DNA obtained from newly infected cells was linearized by digestion with SacI and cloned into AgtWESAXB. The following three different molecules were isolated: FSV-1 (4.4 kilobases [kb]) and FSV-2 (4.7 kb), which appeared
more » ... b), which appeared to be full-length FSV DNA molecules containing either one or two copies of the long terminal repeat structure, and FSV-3 (6 kb), which consisted of part FSV DNA and part DNA of unknown origin. An analysis of the structure of cloned FSV-1 and FSV-2 DNA molecules by restriction endonuclease mapping and hybridization with appropriate probes showed that about 2.6 kb of the FSV-unique sequence called FSV-fps is located in the middle of the FSV genome and is flanked by helper virus-derived sequences of about 1.3 kb at the 5' end and 0.5 kb at the 3' end. The long terminal repeats of FSV were found to have no cleavage site for either EcoRI or PvuI. Upon transfection, both FSV-1 DNA and FSV-2 DNA were able to transform mammalian fibroblasts. Four 32P-labeled DNA fragments derived from different portions of the FSV-fps sequence were used for hybridization to viral RNAs. We found that sequences within the 3' half of the FSV-fps gene are homologous to RNAs of PRCII avian sarcoma virus and the Snyder-Theilen strain offeline sarcoma virus, both of which were previously shown to contain transforming genes related to FSV-fps. These results suggest that the 3' portion of the FSV-fps sequence may be crucial for the transforming activity offps-related oncogenic sequences. Fujinami sarcoma virus (FSV) (14), a replication-defective avian sarcoma virus, has a 4.6kilobase (kb) genome containing about 3 kb of a unique sequence unrelated to helper virus sequences (19, 25) . This unique sequence has been identified as being essential for the transforming activity of the virus (12, 18, 31). Since hybridization studies have shown that this unique FSV sequence is shared with PRCII avian sarcoma virus (34), this oncogenic sequence is calledfps. A nucleotide sequence homologous tofps (c-fps) has been detected in the cellular DNAs of uninfected chickens and a wide variety of vertebrates; the degree of homology among these sequences is inversely related to the phylogenetic distance of a species from the chicken (33a). Thus, as postulated for many transforming retroviruses, FSV appears to have been generated by a process of recombination between prototype avian retrovirus sequences and the c-fps gene in chicken DNA. The FSV genome encodes a 140-kilodalton protein (P140) which is a fusion product between amino acid sequences encoded by the gag information remaining on the FSV genome and amino acid sequences encoded by the fps sequence of FSV (FSV-fps). Immunoprecipitates of FSV P140 are associated with a protein kinase activity which phosphorylates tyrosine residues on substrate proteins, as has been found for other avian sarcoma virus transforming gene products (12, 31). In a previous paper we showed that the FSVfps sequence is related not only to the transforming sequence of PRCII but also to the transforming sequences of the Gardner-Arnstein (15) and Snyder-Theilen (ST) (35) strains of feline sarcoma virus (FeSV) (34). More recently, another isolate of avian sarcoma virus, UR1, has also been found to contain the fps sequence (2, 41). Nucleotide sequence homology among FSV, PRCII, and FeSV has been supported by immunological and peptide map analyses of the fusion proteins of these viruses (3, 4). However, the extent of hybridization between DNA complementary to the FSV-fps sequence (cDNAFsvfp,s) 1007 on May 9, 2020 by guest
doi:10.1128/jvi.42.3.1007-1016.1982 fatcat:icpmmhhx3jb5tgssfhvslyo4ku