Abstract
Adaptive point mutation and amplification are induced responses to environmental stress, promoting genetic changes that can enhance survival. A specialized adaptive mutation mechanism has been documented in one Escherichia coli assay, but its enzymatic basis remained unclear. We report that the SOS-inducible, error-prone DNA polymerase (pol) IV, encoded by dinB, is required for adaptive point mutation in the E. coli lac operon. A nonpolar dinB mutation reduces adaptive mutation frequencies by 85% but does not affect adaptive amplification, growth-dependent mutation, or survival after oxidative or UV damage. We show that pol IV, together with the major replicase, pol III, can account for all adaptive point mutations at lac. The results identify a role for pol IV in inducible genetic change.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptation, Physiological / genetics*
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Bacterial Proteins / genetics
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Base Pair Mismatch / genetics
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Base Sequence
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DNA Polymerase III / metabolism
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DNA Polymerase beta / genetics
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DNA Polymerase beta / metabolism*
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Escherichia coli / enzymology*
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Escherichia coli / genetics*
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Escherichia coli / growth & development
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Escherichia coli Proteins*
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Evolution, Molecular
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Frameshift Mutation / genetics
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Gene Amplification / genetics*
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Genotype
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Kinetics
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Lac Operon / genetics
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Mutagenesis / genetics*
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Mutation, Missense / genetics
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Oxidative Stress
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Piperazines
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Point Mutation / genetics
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Purines
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SOS Response, Genetics / genetics*
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Sequence Deletion / genetics
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Serine Endopeptidases / genetics
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Sildenafil Citrate
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Sulfones
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Ultraviolet Rays
Substances
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Bacterial Proteins
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DinB protein, E coli
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Escherichia coli Proteins
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LexA protein, Bacteria
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Piperazines
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Purines
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Sulfones
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Sildenafil Citrate
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DNA Polymerase III
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DNA Polymerase beta
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Serine Endopeptidases