The Simian Virus 40 Core Origin Contains Two Separate Sequence Modules That Support T-Antigen Double-Hexamer Assembly
AUTOR(ES)
Sreekumar, K. R.
FONTE
American Society for Microbiology
RESUMO
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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=116372Documentos Relacionados
- Phosphorylation of Simian Virus 40 T Antigen on Thr 124 Selectively Promotes Double-Hexamer Formation on Subfragments of the Viral Core Origin
- Two Regions of Simian Virus 40 T Antigen Determine Cooperativity of Double-Hexamer Assembly on the Viral Origin of DNA Replication and Promote Hexamer Interactions during Bidirectional Origin DNA Unwinding
- Sequence Requirements for the Assembly of Simian Virus 40 T Antigen and the T-Antigen Origin Binding Domain on the Viral Core Origin of Replication
- Assembly of T-Antigen Double Hexamers on the Simian Virus 40 Core Origin Requires Only a Subset of the Available Binding Sites
- Large T-Antigen Double Hexamers Imaged at the Simian Virus 40 Origin of Replication