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Journal of Virology, March 2001, p. 2839-2847, Vol. 75, No. 6
Department of Biological Sciences, University
of Delaware, Newark, Delaware 19716-2590
Received 2 October 2000/Accepted 22 December 2000
We have previously mapped the single-stranded DNA binding domain of
large T antigen to amino acid residues 259 to 627. By using internal
deletion mutants, we show that this domain most likely begins after
residue 301 and that the region between residues 501 and 550 is not
required. To study the function of this binding activity, a series of
single-point substitutions were introduced in this domain, and the
mutants were tested for their ability to support simian virus 40 (SV40)
replication and to bind to single-stranded DNA. Two
replication-defective mutants (429DA and 460EA) were grossly impaired
in single-stranded DNA binding. These two mutants were further tested
for other biochemical activities needed for viral DNA replication. They
bound to origin DNA and formed double hexamers in the presence of ATP.
Their ability to unwind origin DNA and a helicase substrate was
severely reduced, although they still had ATPase activity. These
results suggest that the single-stranded DNA binding activity is
involved in DNA unwinding. The two mutants were also very defective in
structural distortion of origin DNA, making it likely that
single-stranded DNA binding is also required for this process. These
data show that single-stranded DNA binding is needed for at least two
steps during SV40 DNA replication.
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.6.2839-2847.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Role of Single-Stranded DNA Binding Activity of T
Antigen in Simian Virus 40 DNA Replication
*
Corresponding author. Mailing address: Department of
Biological Sciences, University of Delaware, Newark, DE 19716-2590. Phone: (302) 831-8547. Fax: (302) 831-2281. E-mail:
dsimmons{at}udel.edu.
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