Characterization of dinY, a new Escherichia coli DNA repair gene whose products are damage inducible even in a lexA(Def) background

Abstract

Bacteriophage Mu dX(Ap lac) was used to isolate a mutation in an Escherichia coli lexA(Def) strain representing a previously undescribed gene (dinY) which does not seem to be under the direct control of LexA. The insertion created a dinY::lacZ fusion in which beta-galactosidase expression required a DNA-damaging treatment (UV irradiation or mitomycin) and activable RecA protein. This strain showed a decreased Weigle reactivation of bacteriophage lambda. However, it was fully inducible for UV mutagenesis. Two-dimensional gel electrophoresis analysis identified two spots absent in the mutant which were both UV inducible only in the presence of activated RecA protein (RecA*). This finding suggests that the dinY::lacZ fusion lies in a gene either that is under the direct control of activated RecA or whose product undergoes RecA*-dependent posttranscriptional/posttranslational modification(s). The dinY gene may also control the expression of some other gene(s) and/or lie in an operon. The fusion was mapped at a position between 41 and 41.5 min on the E. coli chromosome, in the vicinity of the ruv operon.

The genetic requirements for UmuDC-mediated cold sensitivity are distinct from those for SOS mutagenesis

“…If the latter is the case, these genes must be under the negative control of a repressor protein other than LexA, since the strains used in these experiments are lexA(Def). Several genes in the SOS regulon, such as sfiC (8) or dinY (36), have been shown to be regulated by RecA but not repressed by LexA. In addition, there are several examples of genes, such as dnaA, dnaN, dnaQ, phr, and recQ (28), that appear to be regulated in a recA-and lexA-dependent manner but have not been shown to be directly repressed by LexA.…”

“…In addition, there are several examples of genes, such as dnaA, dnaN, dnaQ, phr, and recQ (28), that appear to be regulated in a recA-and lexA-dependent manner but have not been shown to be directly repressed by LexA. It has been suggested that the expression of these genes is controlled by other unknown repressors that are inactivated by RecA*-facilitated cleavage (36). It is possible that one or more of these genes, or an unknown gene that is similarly regulated, plays a role in the alleviation of UmuDC-mediated inhibition of growth at 30ЊC.…”

Several pathways of hydrogen peroxide action that damage the E. coli genome

“…In fact, Petit et al (1993) have characterized an E. coli gene, dinY, whose induction does not require the cleavage of LexA repressor, although it may be considered a member of the SOS regulon (Petit et al, 1993;Friedberg et al, 1995). The protective effect induced by H 2 O 2 against UV is shown to be independent of the induction of dinY gene or other genes under the same control as dinY (Asad et al, 2000).…”

sfi-independent filamentation in Escherichia coli Is lexA dependent and requires DNA damage for induction

“…The class II SOS genes also require functional RecA and LexA for induction but do not appear to be under direct transcriptional control of LexA. It has been suggested that the mechanism of induction may require the coprotease function of RecA to process a protein other than LexA (38). Some of the genes that are currently classified in this group are dinY, dnaA, dnaN, dnaQ, eda, phr, recQ, and sfiC (4, 26-28, 31, 38).…”