Molecular Events and Molecules That Lead to Induction of Prophage and SOS Functions

Abstract

Inhibition of DNA replication in bacteria induces a variety of cellular processes which have been designated as SOS functions (Witkin 1974; Radman 1974). A typical example of the SOS functions is prophage induction which was originally discovered by Lwoff in Bacillus megatherium following ultraviolet (UV) irradiation (Lwoff et al. 1950). Certain genes and their products have now been identified with the induction of SOS functions (for review, see Witkin 1976). Among them, the X protein associated with induction of SOS functions (Gudas and Pardee 1975) and the recA-gene protein product (McEntee et al. 1976) were recently demonstrated to be identical (Emmerson and West 1977; McEntee 1977; Gudas and Mount 1977). There is evidence that protease activity associated with recA protein inactivates repressor molecules (Roberts et al. 1977). Little is known, however, about the initial molecular events which trigger the SOS functions. Kirby et al. (1967) proposed that an adenine derivative...