Format

Send to

Choose Destination
J Bacteriol. 1992 Apr;174(8):2517-24.

Overproduction of the beta subunit of DNA polymerase III holoenzyme reduces UV mutagenesis in Escherichia coli.

Author information

1
Department of Biochemistry, Weizmann Institute of Science, Rehovot, Israel.

Abstract

Overproduction of the beta subunit of DNA polymerase III holoenzyme caused a 5- to 10-fold reduction of UV mutagenesis along with a slight increase in sensitivity to UV light in Escherichia coli. The same effects were observed in excision-deficient cells, excluding the possibility that they were mediated via changes in excision repair. In contrast, overproduction of the alpha subunit of the polymerase did not influence either UV mutagenesis or UV sensitivity. The presence of the mutagenesis proteins MucA and MucB expressed from a plasmid alleviated the effect of overproduced beta on UV mutagenesis. We have previously suggested that DNA polymerase III holoenzyme can exist in two forms: beta-rich form unable to bypass UV lesions and a beta-poor form capable of bypassing UV lesions (O. Shavitt and Z. Livneh, J. Biol. Chem. 264:11275-11281, 1989). The beta-poor form may be related to an SOS form of DNA polymerase III designed to perform translesion polymerization under SOS conditions and thereby generate mutations. On the basis of this model, we propose that the overproduced beta subunit affects the relative abundance of the regular replicative beta-rich polymerase and the SOS bypass-proficient polymerase by sequestering the polymerase molecules to the beta-rich form and blocking the SOS form.

PMID:
1556072
PMCID:
PMC205890
DOI:
10.1128/jb.174.8.2517-2524.1992
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center