L-Homoserylaminoethanol, a novel dipeptide alcohol inhibitor of eukaryotic DNA polymerase ε from a plant cultured cells, Nicotina tabacum L.

Abstract

We found a novel inhibitor specific to eukaryotic DNA polymerase ε (pol ε) from plant cultured cells, Nicotina tabacum L. The compound (compound 1) was a dipeptide alcohol, l-homoserylaminoethanol. The 50% inhibition of pol ε activity by the compound was 43.6 μg/mL, and it had almost no effect on the activities of the other eukaryotic DNA polymerases such as α, β, γ and δ, prokaryotic DNA polymerases, nor DNA metabolic enzymes such as human telomerase, human immunodeficiency virus type 1 reverse transcriptase, T7 RNA polymerase, human DNA topoisomerase I and II, T4 polynucleotide kinase and bovine deoxyribonuclease I. Kinetic studies showed that inhibition of pol ε by the compound was non-competitive with respect to both template-primer DNA and nucleotide substrate. We succeeded in chemically synthesizing the stereoisomers, l-homoserylaminoethanol and d-homoserylaminoethanol, and found both were effective to the same extent. The IC50 values of l- and d-homoserylaminoethanols for pol ε were 42.0 and 41.5 μg/mL, respectively. This represents the second discovery of a pol ε-specific inhibitor, and the first report on a water-soluble peptide-like compound as the inhibitor, which is required in biochemical studies of pol ε.