The replication of adenovirus DNA with purified proteins

Abstract

This year marks the 30th anniversary of the discovery of adenoviruses and the publication of the structure of the double helix of DNA, with its implications for the mechanism of DNA replication . Although the structure of DNA suggested that its duplication might be simple, the elegant studies on the replication of procaryotic DNA in vitro have shown that the enzymology of DNA replication is complex . Relatively little is known about eucaryotic cell DNA replication, but adenoviruses have proved to be valuable tools for determining how mammalian cells work and may provide valuable insight into some aspects of cell DNA replication as well . A landmark in this endeavor was the development by Challberg and Kelly (PNAS 76, 655-659, 1979) of a soluble, cell free extract capable of initiation of adenovirus DNA replication on exogenous template DNA . Recent characterization of this cell free system has led to the purification of enzymes that replicate adenovirus DNA, as well as the identification of DNA template requirements for initiation of DNA synthesis . These studies have helped to expound the protein-priming mechanism for the initiation of DNA synthesis at the replication origin . The human adenoviruses contain a double-strand linear genome of -36,000 bp, which contains a protein of 55,000 daltons (terminal protein, TP) covalently attached via a serine-dCMP phosphodiester bond to each 5' terminus (reviewed by Challberg and Kelly, Ann . Rev . Biochem. 51, 901-934, 1982) . Another feature of the termini of adenovirus DNA is an inverted, repeated sequence ranging from 102 to 162 by in various human adenoviruses . This inverted sequence, which contains the origin of DNA replication, allows DNA synthesis to begin at either end of the molecule . Synthesis then proceeds via type I