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Efficient translesion replication in the absence of Escherichia coli Umu proteins and 3'-5' exonuclease proofreading function.
- Source :
-
Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 1998 Dec 22; Vol. 95 (26), pp. 15519-24. - Publication Year :
- 1998
-
Abstract
- Translesion replication (TR) past a cyclobutane pyrimidine dimer in Escherichia coli normally requires the UmuD'2C complex, RecA protein, and DNA polymerase III holoenzyme (pol III). However, we find that efficient TR can occur in the absence of the Umu proteins if the 3'-5' exonuclease proofreading activity of the pol III epsilon-subunit also is disabled. TR was measured in isogenic uvrA6 DeltaumuDC strains carrying the dominant negative dnaQ allele, mutD5, or DeltadnaQ spq-2 mutations by transfecting them with single-stranded M13-based vectors containing a specifically located cis-syn T-T dimer. As expected, little TR was observed in the DeltaumuDC dnaQ+ strain. Surprisingly, 26% TR occurred in UV-irradiated DeltaumuDC mutD5 cells, one-half the frequency found in a uvrA6 umuDC+mutD5 strain. lexA3 (Ind-) derivatives of the strains showed that this TR was contingent on two inducible functions, one LexA-dependent, responsible for approximately 70% of the TR, and another LexA-independent, responsible for the remaining approximately 30%. Curiously, the DeltaumuDC DeltadnaQ spq-2 strain exhibited only the LexA-independent level of TR. The cause of this result appears to be the spq-2 allele, a dnaE mutation required for viability in DeltadnaQ strains, since introduction of spq-2 into the DeltaumuDC mutD5 strain also reduces the frequency of TR to the LexA-independent level. The molecular mechanism responsible for the LexA-independent TR is unknown but may be related to the UVM phenomenon [Palejwala, V. A., Wang, G. E., Murphy, H. S. & Humayun, M. Z. (1995) J. Bacteriol. 177, 6041-6048]. LexA-dependent TR does not result from the induction of pol II, since TR in the DeltaumuDC mutD5 strain is unchanged by introduction of a DeltapolB mutation.
- Subjects :
- Alleles
Bacterial Proteins metabolism
DNA Polymerase III genetics
DNA-Directed DNA Polymerase
Escherichia coli metabolism
Exodeoxyribonuclease V
Exodeoxyribonucleases metabolism
Genotype
Pyrimidine Dimers
Recombinant Proteins metabolism
Serine Endopeptidases genetics
Serine Endopeptidases metabolism
Transduction, Genetic
Transfection
Bacterial Proteins genetics
DNA Damage
DNA Replication
Escherichia coli genetics
Escherichia coli Proteins
Exodeoxyribonucleases genetics
Subjects
Details
- Language :
- English
- ISSN :
- 0027-8424
- Volume :
- 95
- Issue :
- 26
- Database :
- MEDLINE
- Journal :
- Proceedings of the National Academy of Sciences of the United States of America
- Publication Type :
- Academic Journal
- Accession number :
- 9861001
- Full Text :
- https://doi.org/10.1073/pnas.95.26.15519