Role of E-coli DNA helicase II in a umuCD-dependent Wiegle reactivation

Wiegle reactivation is a manifestation of a umuCD-mediated enhancement in the replication of damaged phage DNA (Caillet-Fauquet et al., 1977; Defais et al., 1989; Rajagopalan et al., 1992). I have obtained Wiegle reactivation of lambda by irradiating the uvrA cells in rich growth medium. This Wiegle reactivation was lost upon transduction of the umuC mutation into the strain. There was also a drastic reduction of Wiegle reactivation in an isogenic strain carrying the uvrA mutation and deletion of the uvrD gene. (uvrD codes for E. coli DNA helicase II). The effect of the uvrD deletion on Wiegle reactivation can indicate a specific requirement of DNA helicase II for the unwinding of damaged phage DNA during its replication or (and) an inefficient induction of the SOS response in Delta uvrD uvrA cells.