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| THE SIMIAN VIRUS-40 T-ANTIGEN DOUBLE HEXAMER ASSEMBLES AROUND THE DNA AT THE REPLICATION ORIGIN |
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| Author(s): DEAN FB, BOROWIEC JA, EKI T, HURWITZ J |
| Source: JOURNAL OF BIOLOGICAL CHEMISTRY Volume: 267 Issue: 20 Pages: 14129-14137 Published: JUL 15 1992 |
| Times Cited: 125 References: 72 |
| Abstract: An initial step in the replication of simian virus (SV40) DNA is the ATP-dependent formation of a double hexamer of the SV40 large tumor (T) antigen at the SV40 DNA replication origin. In the absence of DNA, T antigen assembled into hexamers in the presence of magnesium and ATP. Hexameric T antigen was stable and could be isolated by glycerol gradient centrifugation. The ATPase activities of hexameric and monomeric T antigen isolated from parallel glycerol gradients were identical. However, while monomeric T antigen was active in the ATP-dependent binding, untwisting, unwinding, and replication of SV40 origin-containing DNA, hexameric T antigen was inactive in these reactions. Isolated hexamers incubated at 37-degrees-C in the presence of ATP remained intact, but dissociated into monomers when incubated at 37-degrees-0 in the absence of ATP. This dissociation restored the activity of these preparations in the DNA replication reaction, indicating that hexameric T antigen is not permanently inactivated but merely assembled into a nonproductive structure. We propose that the two hexamers of T antigen at the SV40 origin assemble around the DNA from monomer T antigen in solution. This complex untwists the DNA at the origin, melting specific DNA sequences. The resulting single-stranded regions may be utilized by the T antigen helicase activity to initiate DNA unwinding bidirectionally from the origin. |
| Document Type: Article |
| Language: English |
| Reprint Address: DEAN, FB (reprint author), SLOAN KETTERING MEM CANC CTR, PROGRAM MOLEC BIOL, NEW YORK, NY 10021 USA |
Addresses:
1. NYU MED CTR, DEPT BIOCHEM, NEW YORK, NY 10016 USA
2. RIKEN INST PHYS & CHEM RES, TSUKUBA LIFE SCI CTR, GENE BANK, TSUKUBA, IBARAKI 305 JAPAN |
| Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 |
| Subject Category: Biochemistry & Molecular Biology |
| IDS Number: JD325 |
| ISSN: 0021-9258 |
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