A dideoxynucleotide-sensitive DNA polymerase activity characterized from endoreduplicating cells of mungbean (Vigna radiata L.) during ontogeny of cotyledons.
Within this work we describe the purification and biochemical characterization of a ddNTP-sensitive DNA polymerase purified from mungbean (Vigna radiata cv B1, L.) seeds at 18 days after fertilization, when > 70% of the nuclei are reported to be in the endoreduplicated state. The purified enzyme is a single polypeptide of 62 kDa and many of its physicochemical properties are similar to those of mammalian DNA polymerase beta. Similar to the other X-family DNA polymerases, it lacks 3'-5' exonuclease activity and has short gap-filling and strand-displacement activity. The enzyme shows moderately processive DNA synthesis on a single-strand template. The determined N-terminal heptapeptide sequence of the enzyme showed clear homology with helix 1 of the N-terminal single strand DNA-binding domain (residues 32-41) of rat and human DNA polymerase beta. These results represent the first evidence for the identification and characterization of a ddNTP-sensitive DNA polymerase expressed during the endoreduplication cycle that shares biochemical and immunological similarity with mammalian DNA polymerase beta.
Roy
Sujit
S
Department of Botany, Bose Institute, Kolkata, India.
Sarkar
Sailendra Nath
SN
Singh
Sanjay K
SK
Sengupta
Dibyendu N
DN
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018548:Cotyledon / Q000254:growth & development*; D004247:DNA / Q000096:biosynthesis; D017931:DNA Primers; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D003854:Deoxyribonucleotides / Q000494:pharmacology*; D007887:Fabaceae / Q000201:enzymology* / Q000254:growth & development; D008969:Molecular Sequence Data; D008970:Molecular Weight; D019384:Nucleic Acid Synthesis Inhibitors; D051381:Rats
D017931:DNA Primers; D003854:Deoxyribonucleotides; D019384:Nucleic Acid Synthesis Inhibitors; D004247:DNA; D004259:DNA-Directed DNA Polymerase