Three domains in the simian virus 40 core origin orchestrate the binding, melting, and DNA helicase activities of T antigen.
The simian virus 40 (SV40) core origin of replication consists of three functional domains. The sequence 5'-CACTACTTCTGGAATAG-3' with an imperfect inverted repeat (underlined), a palindrome with four 5'-GAGGC-3' pentanucleotide repeats, and a 17-base-pair A + T-rich segment. We have been able to assign primary functions to each domain. Remarkably, SV40 large T antigen melted the inverted repeat domain in the complete absence of other origin sequences. Presumably, this protein-DNA interaction initiates a replication bubble that leads to daughter strand DNA synthesis. The pentanucleotide domain alone docked and arranged T antigen at the origin. The A + T-rich domain had no independent function, but, in the presence of the other two domains, allowed bound T antigen to extend the replication bubble. Thus, three domains of the origin coordinate the binding, melting, and DNA helicase activities of T antigen in an ordered sequence of events to initiate DNA replication.
Parsons
R
R
Department of Microbiology, State University of New York, Stony Brook 11794-8621.
Anderson
M E
ME
Tegtmeyer
P
P
D000952:Antigens, Polyomavirus Transforming / Q000235:genetics* / Q000302:isolation & purification; D001483:Base Sequence; D004265:DNA Helicases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004261:DNA Replication; D004279:DNA, Viral / Q000235:genetics*; D003850:Deoxyribonuclease I; D005814:Genes, Viral; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D009710:Nucleotide Mapping; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D013539:Simian virus 40 / Q000235:genetics* / Q000276:immunology
D000952:Antigens, Polyomavirus Transforming; D004279:DNA, Viral; D011994:Recombinant Proteins; D003850:Deoxyribonuclease I; D004265:DNA Helicases