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Steric Gate Variants in a Y family DNA Polymerase Confer UV‐Hypersensitivity
Author(s) -
Beuning Penny J,
Shurtleff Brenna W,
Sefcikova Jana,
Walker Graham C
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.990.3
Subject(s) - dna polymerase , steric effects , microbiology and biotechnology , polymerase , dna , mutagenesis , dna repair , dna clamp , gene , dna polymerase ii , biology , mutant , chemistry , genetics , polymerase chain reaction , stereochemistry , reverse transcriptase
Induction of the SOS response due to a cell's failed attempts to replicate damaged DNA results in the expression of at least 43 genes in E. coli . The induced genes include umuDC , whose products include the Y‐family DNA polymerase DNA pol V (UmuD′ 2 C). E. coli UmuC is a DNA polymerase with the specialized ability to copy past lesions in the DNA template, but this activity may be mutagenic. Normal, replicative DNA polymerases have a “steric gate” residue that prevents incorporation of ribonucleotides in the nascent DNA, by serving as a steric block to the 2′‐OH. In the Y‐family polymerases, this residue appears important for facilitating lesion bypass activity. We have found that steric gate mutants of UmuC cause extreme cellular sensitivity to UV exposure and are dominant negative at low copy number. Mutations in the known beta clamp binding motifs of UmuC or deletion of the proofreading subunit of DNA pol III suppress the UV hypersensitivity of the steric gate variant. We have found that mutation of residues surrounding the steric gate result in decreased mutagenesis without cellular hypersensitivity to UV light. Supported by a Dreyfus Foundation New Faculty Award.