title: The inhibitory action of pyrrolidine alkaloid, 1,4-dideoxy-1,4-imino-D-ribitol, on eukaryotic DNA polymerases.
abstract: The pyrrolidine alkaloids mimicking the structures of pentose with nitrogen in the ring are known to be inhibitors of glycosidases. We report here that a compound belonging to this category is an inhibitor of eukaryotic DNA polymerases. Among the eight naturally occurring pyrrolidine alkaloids we tested, only one compound, 1,4-dideoxy-1,4-imino-D-ribitol (DRB), which was purified from the mulberry tree (Morus alba), strongly inhibited the activities of eukaryotic DNA polymerases with IC50 values of 21-35 microM, and had almost no effect on the activities of prokaryotic DNA polymerases, nor DNA metabolic enzymes such as human immunodeficiency virus type 1 reverse transcriptase, T7 RNA polymerase, and bovine deoxyribonuclease I. Kinetic studies showed that inhibition of both DNA polymerases alpha and beta by DRB was competitive with respect to dNTP substrate. Whereas DNA polymerase alpha inhibition was noncompetitive with the template-primer, the inhibition of DNA polymerase beta was found to be competitive with the template-primer. The K(i) values of DNA polymerases alpha and beta for the template-primer were smaller than those for dNTP substrate. Therefore, the affinity of DRB was suggested to be higher at the template-primer binding site than at the dNTP substrate-binding site, although DRB is an analogue of deoxyribose consisting of dNTP. Computational analyses of the eight pyrrolidine alkaloids revealed a remarkable difference in the distribution of positive and negative electrostatic charges on the surface of molecules. The relationship between the structure of DRB and the inhibition of eukaryotic DNA polymerases is discussed.
authors.affiliation: Department of Nutritional Science, Laboratory of Food and Nutritional Sciences, Kobe-Gakuin University, Nishi-ku, Kobe, 651-2180, Hyogo, Japan. mizushin@nutr.kobegakuin.ac.jp <mizushin@nutr.kobegakuin.ac.jp>
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Mizushina
authors.forename: Xianai
authors.initials: X
authors.lastname: Xu
authors.forename: Naoki
authors.initials: N
authors.lastname: Asano
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kasai
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kato
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takemura
authors.forename: Hitomi
authors.initials: H
authors.lastname: Asahara
authors.forename: Stuart
authors.initials: S
authors.lastname: Linn
authors.forename: Fumio
authors.initials: F
authors.lastname: Sugawara
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yoshida
authors.forename: Kengo
authors.initials: K
authors.lastname: Sakaguchi
mesh_terms: D000470:Alkaloids / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D000818:Animals; D001089:Arabinose; D004256:DNA Polymerase I / Q000378:metabolism; D019951:DNA Polymerase beta / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005057:Eukaryotic Cells / Q000201:enzymology; D006801:Humans; D050113:Imino Furanoses; D007700:Kinetics; D008958:Models, Molecular; D031625:Morus / Q000737:chemistry; D011759:Pyrrolidines / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D055672:Static Electricity; D013402:Sugar Alcohols / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000470:Alkaloids; D004791:Enzyme Inhibitors; D050113:Imino Furanoses; D011759:Pyrrolidines; D013402:Sugar Alcohols; C058137:1,4-dideoxy-1,4-iminoarabinitol; D001089:Arabinose; D004256:DNA Polymerase I; D019951:DNA Polymerase beta; D004259:DNA-Directed DNA Polymerase