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Active site mutations in the Y family DNA polymerase UmuC cause hypersensitivity to UV light and are dominant negative
Author(s) -
Beuning Penny J,
Addepalli Haripriya,
Walker Graham C
Publication year - 2007
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.21.5.a659-b
Subject(s) - dna polymerase , mutagenesis , polymerase , microbiology and biotechnology , dna , steric effects , biology , dna repair , dna polymerase ii , gene , dna replication , dna clamp , genetics , chemistry , mutant , polymerase chain reaction , reverse transcriptase , stereochemistry
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 are the Y‐family DNA polymerase DNA pol V (UmuC) and its accessory proteins, UmuD and its cleaved form UmuD'. E. coli UmuC is a DNA polymerase with the specialized ability to copy past lesions in the DNA template, but this activity results in mutagenesis when copying DNA that contains the products of UV irradiation. 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 their 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 substantial decreases in UV‐mutagenesis, as well as cellular sensitivity to UV exposure, and are dominant negative at low copy number. We are currently characterizing other residues surrounding the steric gate. Supported by NIH and a Dreyfus Foundation New Faculty Award.