Deletion of the Saccharomyces cerevisiae gene RAD30 encoding an Escherichia coli DinB homolog confers UV radiation sensitivity and altered mutability

Abstract

The dinB gene of Escherichia coli is an SOS-inducible gene of unknown function. Its mode of regulation and the amino acid sequence similarity of the predicted DinB protein to the UmuC protein of E. coli both suggest a role in cellular responses to DNA damage and probably in error-prone repair. Proteins with sequence similarity to DinB have been predicted from genes cloned from various prokaryotic and eukaryotic organisms, including Caenorhabditis elegans. Here we present the phenotypic characterization of a haploid Saccharomyces cerevisiae strain deleted for the ORF YDR419W, encoding a yeast DinB homolog. The deletion mutant is viable but is moderately sensitive to killing following exposure to ultraviolet (UV) radiation. Hence, we have named the gene RAD30. Steady-state levels of RAD30 transcripts are increased following UV irradiation. UV-induced locus-specific reversion of an ochre allele (arg4-17) is reduced in the rad30 deletion mutant. However, enhanced mutability was observed following treatment with the alkylating agent methylmethanesulfonate (MMS). Spontaneous mutability was also slightly increased. We conclude that RAD30 encodes an accessory function involved in DNA repair and mutagenesis. We speculate that the relatively weak phenotype and the opposite effects on mutability as a function of the type of DNA damage involved may derive from a functional redundancy of yeast proteins which facilitate replicative bypass of non-coding DNA lesions.

Handling the 3-methylcytosine lesion by six human DNA polymerases members of the B-, X- and Y-families

“…We further confirmed its importance in the context of a whole cell; by showing that lack of Pol η in human cell extracts results in a severely reduced ability to act at the site of 3meC (Figure 6C). The importance of functional Pol η in response to monoalkylating agents has been already suggested by in vivo experiments showing that the Saccharomyces cerevisiae rad30D strain lacking Pol η is somewhat sensitive to MMS (33,34). Furthermore, MMS treatment of human cells was shown to result in formation of Pol η foci at the site of replication forks blocked by alkylation lesions (35), one of which is potentially 3meC.…”

Monoubiquitylation of histone H2B contributes to the bypass of DNA damage during and after DNA replication

“…4 C – E ); whereas the sensitivity of TS mutants ( mms2Δ , ubc13Δ ) was only mildly affected by htb-K123R , strong synergism was observed in combination with TLS mutants ( rev3Δ , rev7Δ ). Unlike rev3Δ and rev7Δ , another TLS mutant, rad30Δ , displayed only mild additivity; however, the protein encoded by RAD30 , polymerase η, is rather specific for UV damage and does not contribute significantly to the processing of MMS lesions (52). The other exception to the pattern was rad5Δ , which displayed significant synergism with htb-K123R ; however, beyond its contribution to TS, the Rad5 protein harbors helicase activity with a function in a poorly described pathway of replicative stress management, which could account for a TS-independent contribution (53).…”

Translesion DNA Polymerases

“…S. cerevisiae RAD30 was identified in 1997, as an ortholog of E. coli UmuC and DinB proteins that is involved in error-free repair of UV damage (McDonald et al 1997; Roush et al 1998). In 1999, the RAD3 0 gene was subsequently shown to encode Pol η, which can bypass a T-T CPD efficiently and with the same accuracy as undamaged DNA (Johnson et al 1999b).…”