title: Beta-sitosterol-3-O-beta-D-glucopyranoside: a eukaryotic DNA polymerase lambda inhibitor.
abstract: Beta-sitosterol-3-O-beta-D-glucopyranoside (compound 1), a steroidal glycoside isolated from onion (Allium cepa L.) selectively inhibited the activity of mammalian DNA polymerase lambda (pol lambda) in vitro. The compound did not influence the activities of replicative DNA polymerases such as alpha, delta and epsilon, but also showed no effect even on the activity of pol beta which is thought to have a very similar three-dimensional structure to the pol beta-like region of pol lambda. Since parts of compound 1 such as beta-sitosterol (compound 2) and D-glucose (compound 3) did not influence the activities of any enzymes tested, the converted structure of compounds 2 and 3 might be important for pol lambda inhibition. The inhibitory effect of compound 1 on both intact pol lambda (i.e. residues 1-575) and a truncated pol lambda lacking the N-terminal BRCA1 C-terminus (BRCT) domain (133-575, del-1 pol lambda) was dose-dependent, and 50% inhibition was observed at a concentration of 9.1 and 5.4 microM, respectively. The compound 1-induced inhibition of del-1 pol lambda activity was non-competitive with respect to both the DNA template-primer and the dNTP substrate. On the basis of these results, the pol lambda inhibitory mechanism of compound 1 is discussed.
authors.affiliation: Laboratory of Food & Nutritional Sciences, Department of Nutritional Science, Kobe-Gakuin University, Kobe, Hyogo 651-2180, Japan. mizushin@nutr.kobegakuin.ac.jp
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Mizushina
authors.forename: Rumi
authors.initials: R
authors.lastname: Nakanishi
authors.forename: Isoko
authors.initials: I
authors.lastname: Kuriyama
authors.forename: Kohei
authors.initials: K
authors.lastname: Kamiya
authors.forename: Toshiko
authors.initials: T
authors.lastname: Satake
authors.forename: Noriko
authors.initials: N
authors.lastname: Shimazaki
authors.forename: Osamu
authors.initials: O
authors.lastname: Koiwai
authors.forename: Yukinobu
authors.initials: Y
authors.lastname: Uchiyama
authors.forename: Yuko
authors.initials: Y
authors.lastname: Yonezawa
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takemura
authors.forename: Kengo
authors.initials: K
authors.lastname: Sakaguchi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yoshida
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002384:Catalysis; D002417:Cattle; D019951:DNA Polymerase beta / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004331:Drosophila melanogaster / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D005057:Eukaryotic Cells / Q000201:enzymology*; D005947:Glucose / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009154:Mutation / Q000235:genetics; D019697:Onions / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry; D051381:Rats; D012855:Sitosterols / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D005960:Glucosides; D010446:Peptide Fragments; D012855:Sitosterols; C472604:sitosterol-3-O-glucopyranoside; C025473:gamma-sitosterol; C415367:DNA polymerase beta2; D019951:DNA Polymerase beta; D005947:Glucose