An insight into the biological functions of family X-DNA polymerase in DNA replication and repair of plant genome

摘要

Recently we have reported the characterization of a novel singjle subunit 62-kDa polypeptide with ddNTP-sensitive DNA polymerase activity from the developing seeds of mungbean (Vigna radiata). The protein showed higher expression and activity level during nuclear endoreduplication stages of mungbean seeds and similarity with mammalian DNA polymerase beta in many physico-chemical properties. The enzyme was found to specifically interact with PCNA (proliferating cell nuclear antigen), and expressed inboth meristematic and meiotic tissues. Functional assays have demonstrated binding of die enzyme to normal and mismatched DNA substrates and widi fidelity DNA synthesis in moderately processive mode, suggesting probable involvement of the enzyme in bodireplication and recombination. Here we have discussed the position of mungbean DNA polymerase as a homologue of DNA Pol lambda, one of the newly identified member of family-X DNA polymerase in plants and illustrated the functional relevance of this enzyme in maintaining the coordination between DNA replication and repair in plant genome.