The simian virus 40 core origin contains two separate sequence modules that support T-antigen double-hexamer assembly.
Using subfragments of the simian virus 40 (SV40) core origin, we demonstrate that two alternative modules exist for the assembly of T-antigen (T-ag) double hexamers. Pentanucleotides 1 and 3 and the early palindrome (EP) constitute one assembly unit, while pentanucleotides 2 and 4 and the AT-rich region constitute a second, relatively weak, assembly unit. Related studies indicate that on the unit made up of pentanucleotide 1 and 3 and the EP assembly unit, the first hexamer forms on pentanucleotide 1 and that owing to additional protein-DNA and protein-protein interactions, the second hexamer is able to form on pentanucleotide 3. Oligomerization on the unit made up of pentanucleotide 2 and 4 and the AT-rich region is initiated by assembly of a hexamer on pentanucleotide 4; subsequent formation of the second hexamer takes place on pentanucleotide 2. Given that oligomerization on the SV40 origin is limited to double-hexamer formation, it is likely that only a single module is used for the initial assembly of T-ag double hexamers. Finally, we discuss the evidence that nucleotide hydrolysis is required for the remodeling events that result in the utilization of the second assembly unit.
Sreekumar
K R
KR
Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Prack
A E
AE
Winters
D R
DR
Barbaro
B A
BA
Bullock
P A
PA
D000255:Adenosine Triphosphate / Q000737:chemistry; D000266:Adenylyl Imidodiphosphate / Q000737:chemistry; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000737:chemistry / Q000502:physiology*; D001483:Base Sequence; D004279:DNA, Viral / Q000737:chemistry; D008954:Models, Biological; D008969:Molecular Sequence Data; D009841:Oligonucleotides / Q000737:chemistry; D011485:Protein Binding; D018741:Replication Origin; D013539:Simian virus 40 / Q000235:genetics / Q000502:physiology*; D014758:Viral Core Proteins / Q000737:chemistry / Q000502:physiology*; D019065:Virus Assembly
D000952:Antigens, Polyomavirus Transforming; D004279:DNA, Viral; D009841:Oligonucleotides; D014758:Viral Core Proteins; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate