1 research outputs found
Characterization of Nine Cancer-Associated Variants in Human DNA Polymerase κ
Specialized
DNA damage-bypass Y-family DNA polymerases contribute
to cancer prevention by providing cellular tolerance to DNA damage
that can lead to mutations and contribute to cancer progression by
increasing genomic instability. Y-family polymerases can also bypass
DNA adducts caused by chemotherapy agents. One of the four human Y-family
DNA polymerases, DNA polymerase (pol) κ, has been shown to be
specific for bypass of minor groove adducts and inhibited by major
groove adducts. In addition, mutations in the gene encoding pol κ
are associated with different types of cancers as well as with chemotherapy
responses. We characterized nine variants of pol κ whose identity
was inferred from cancer-associated single nucleotide polymorphisms
for polymerization activity on undamaged and damaged DNA, their abilities
to extend from mismatched or damaged base pairs at primer termini,
and overall stability and dynamics. We find that these pol κ
variants generally fall into three categories: similar activity to
wild-type (WT) pol κ (L21F, I39T, P169T, F192C, and E292K),
more active than WT pol κ (S423R), and less active than pol
κ (R219I, R298H, and Y432S). Of these, only pol κ variants
R298H and Y432S had markedly reduced thermal stability. Molecular
dynamics (MD) simulations with undamaged DNA revealed that the active
variant F192C and more active variant S423R with either correct or
incorrect incoming nucleotide mimic WT pol κ with the correct
incoming nucleotide, whereas the less active variants R219I, R298H,
and Y432S with the correct incoming nucleotide mimic WT pol κ
with the incorrect incoming nucleotide. Thus, the observations from
MD simulations suggest a possible explanation for the observed experimental
results that pol κ adopts specific active and inactive conformations
that depend on both the protein variant and the identity of the DNA
adduct