Production of simian virus 40 large tumor antigen in bacteria: altered DNA-binding specificity and dna-replication activity of underphosphorylated large tumor antigen.
A bacterial expression system was used to produce simian virus 40 large tumor antigen (T antigen) in the absence of the extensive posttranslational modifications that occur in mammalian cells. Wild-type T antigen produced in bacteria retained a specific subset of the biochemical activities displayed by its mammalian counterpart. Escherichia coli T antigen functioned as a helicase and bound to DNA fragments containing either site I or the wild-type origin of replication in a manner identical to mammalian T antigen. However, T antigen purified from E. coli did not efficiently bind to site II, an essential cis element within the simian virus 40 origin of replication. It therefore could not unwind origin-containing plasmids or efficiently replicate simian virus 40 DNA in vitro. The ability of protein phosphorylation to modulate the intrinsic preference of full-length T antigen for either site I or site II is discussed.
Mohr
I J
IJ
Cold Spring Harbor Laboratory, NY 11724.
Gluzman
Y
Y
Fairman
M P
MP
Strauss
M
M
McVey
D
D
Stillman
B
B
Gerard
R D
RD
D000952:Antigens, Polyomavirus Transforming / Q000235:genetics*; D001483:Base Sequence; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D006367:HeLa Cells / Q000276:immunology; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D010957:Plasmids; D015183:Restriction Mapping; D013539:Simian virus 40 / Q000235:genetics* / Q000276:immunology
D000952:Antigens, Polyomavirus Transforming; D004268:DNA-Binding Proteins; D015345:Oligonucleotide Probes