Mechanism of phage phiX174 DNA inactivation by benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide.

Abstract
A previous report showed that certain derivatives of polycyclic aromatic hydrocarbons bind to .vphi.X174 DNA and render it noninfectious. The present work describes the relationship between the extent of .vphi.X174 DNA binding by (.+-.)-anti-benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide and the effect on infectivity. One molecule of bound diolepoxide is probably sufficient to inhibit the replication of a single molecule of .vphi.X174 DNA. DNA synthesis studies in vitro indicate that when .vphi.X DNA bound by benzo[a]pyrene groups serves as template the rate of DNA polymerization is reduced and less product is formed. The propagation of synthetic DNA strands is blocked so that incomplete complementary chains are assembled. The relationship of these findings to the mutagenic and carcinogenic process associated with the action of benzo[a]pyrene-diolepoxide is discussed.