Cp. Rubinstein et al., NORMAL INDUCTION OF THE SOS RESPONSE IN BACILLUS-SUBTILIS IS PREVENTED BY THE MUTANT REPRESSOR FROM PHAGE PHI-105CTS23, FEMS microbiology letters, 167(2), 1998, pp. 315-320
The presence of the Phi 105cts23 mutant prophage in Bacillus subtilis
induces a series of pleiotropic effects that could be ascribed to an a
nti-SOS activity. In order to circumvent the phage function responsibl
e for this phenomenon, the cts23 mutant repressor was cloned and seque
nced. The isolated repressor reduced the survival capacity of the host
cells after mitomycin C or nalidixic acid treatments and lowered the
spontaneous reversion frequency. When SOS induction kinetics were stud
ied, low or null induction of the damage-inducible din22::LacZ fusion
was observed. In contrast, the presence of the wild-type prophage ampl
ified the SOS response. Sequencing of the mutant repressor revealed th
at the cts23 mutation is a T --> C transition affecting the 5' closest
codon to one of the two reported DNA binding domains. (C) 1998 Federa
tion of European Microbiological Societies. Published by Elsevier Scie
nce B.V. All rights reserved.