Beta-sitosterol-3-O-beta-D-glucopyranoside: a eukaryotic DNA polymerase lambda inhibitor.
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.
Mizushina
Yoshiyuki
Y
Laboratory of Food & Nutritional Sciences, Department of Nutritional Science, Kobe-Gakuin University, Kobe, Hyogo 651-2180, Japan. mizushin@nutr.kobegakuin.ac.jp
Nakanishi
Rumi
R
Kuriyama
Isoko
I
Kamiya
Kohei
K
Satake
Toshiko
T
Shimazaki
Noriko
N
Koiwai
Osamu
O
Uchiyama
Yukinobu
Y
Yonezawa
Yuko
Y
Takemura
Masaharu
M
Sakaguchi
Kengo
K
Yoshida
Hiromi
H
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
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