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The simian virus 40 core origin contains two separate sequence modules that support T-antigen double-hexamer assembly
K R Sreekumar1, A E Prack, D R Winters
1Department of Biochemistry, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
Journal of Virology
|August 23, 2000
Summary
Two distinct pathways assemble simian virus 40 (SV40) T-antigen (T-ag) double hexamers on the viral origin. These assembly units involve specific DNA sequences and protein interactions, with nucleotide hydrolysis potentially remodeling the second pathway.
Area of Science:
- Molecular Biology
- Virology
- Biochemistry
Background:
- Simian virus 40 (SV40) T-antigen (T-ag) is crucial for viral DNA replication.
- Understanding T-ag assembly at the SV40 origin is key to viral replication mechanisms.
Purpose of the Study:
- To elucidate the alternative assembly pathways of T-ag double hexamers on the SV40 core origin.
- To identify the specific DNA elements and their roles in T-ag hexamer formation.
Main Methods:
- Analysis of SV40 core origin subfragments.
- Investigating T-antigen (T-ag) double hexamer assembly dynamics.
- Examining protein-DNA and protein-protein interactions during assembly.
Main Results:
- Two distinct assembly modules for T-ag double hexamers were identified.
- Module 1: Pentanucleotides 1 & 3 with the early palindrome (EP).
- Module 2: Pentanucleotides 2 & 4 with the AT-rich region, a weaker unit.
- Assembly initiation sites and sequential hexamer formation differ between modules.
- Nucleotide hydrolysis is implicated in remodeling for the second assembly unit's utilization.
Conclusions:
- SV40 T-ag double hexamer assembly can proceed via at least two alternative pathways.
- The specific DNA sequence elements dictate the assembly route and efficiency.
- Initial assembly likely utilizes a single module, with nucleotide hydrolysis potentially facilitating the use of the second module.