Kwc. Peden et al., EFFECTS OF MUTATIONS WITHIN THE SV40 LARGE T-ANTIGEN ATPASE P53 BINDING DOMAIN ON VIRAL REPLICATION AND TRANSFORMATION/, Virus genes, 16(2), 1998, pp. 153-165
The simian virus 40 (SV40) large T antigen is a 708 amino-acid protein
possessing multiple biochemical activities that play distinct roles i
n productive infection or virus-induced cell transformation. The carbo
xy-terminal portion of T antigen includes a domain that carries the nu
cleotide binding and ATPase activities of the protein, as well as sequ
ences required for T antigen to associate with the cellular tumor supp
ressor p53. Consequently this domain functions both in viral DNA repli
cation and cellular transformation. We have generated a collection of
SV40 mutants with amino-acid deletions, insertions or substitutions in
specific domains of the protein. Here we report the properties of nin
e mutants with single or multiple substitutions between amino acids 40
2 and 430, a region thought to be important for both the p53 binding a
nd ATPase functions. The mutants were examined for the ability to prod
uce infectious progeny virions, replicate viral DNA in vivo, perform i
n trans complementation tests, and transform established cell lines. T
wo of the mutants exhibited a wildtype phenotype in all these tests. T
he remaining seven mutants were defective for plaque formation and vir
al DNA replication, but in each case these defects could be complement
ed by a wild-type T antigen supplied in trans. One of these replicatio
n-defective mutants efficiently transformed the REF52 and C3H10T1/2 ce
ll lines as assessed by the dense-focus assay. The remaining six mutan
ts were defective for transforming REF52 cells and transformed the C3H
10T1/2 line with a reduced efficiency. The ability of mutant T antigen
to transform REF52 cells correlated with their ability to induce incr
eased levels of p53.