tailieunhanh - Báo cáo khoa học: 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 characteriza-tion of a ddNTP-sensitive DNA polymerase purified from mungbean (Vigna radiatacv B1, L.) seeds at 18 days after fertilization, when 70% of the nuclei are reported to be in the endoreduplicated state. | ỊFEBS Journal A dideoxynucleotide-sensitive DNA polymerase activity characterized from endoreduplicating cells of mungbean Vigna radiata L. during ontogeny of cotyledons Sujit Roy Sailendra Nath Sarkar Sanjay K. Singh and Dibyendu N. Sengupta Department of Botany Bose Institute Kolkata India Keywords endoreduplication days after fertilization ddNTP DNA polymerase b processivity Correspondence D. N. Sengupta Department of Botany Bose Institute 93 1 . Road Kolkata 700 009 India Fax 91 33 235 06790 Tel. 91 33 2350 6619 ext. 340 E-mail dn_sengupta@ Present address Department of Botany University of Calcutta 35 Ballygunge Circular Road Calcutta-700019 India Received 11 December 2006 revised 31 January 2007 accepted 15 February 2007 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 b. 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 b 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 b. doi The replication and repair of DNA involve the concerted activity of several enzymes and protein factors including