Steric bulk at cycloartenol synthase position 481 influences cyclization and deprotonation.
Cycloartenol synthase converts oxidosqualene to the pentacyclic sterol precursor cycloartenol. An Arabidopsis thaliana cycloartenol synthase Ile481Val mutant was previously shown to produce lanosterol and parkeol in addition to its native product cycloartenol. Experiments are described here to construct Phe, Leu, Ala, and Gly mutants at position 481 and to determine their cyclization product profiles. The Phe mutant was inactive, and the Leu mutant produced cycloartenol and parkeol. The Ala and Gly mutants formed lanosterol, cycloartenol, parkeol, achilleol A, and camelliol C. Monocycles comprise most of the Gly mutant product, showing that an alternate cyclization route can be made the major pathway by a single nonpolar mutation.
Department of Chemistry and Department of Biochemistry and Cell Biology, Rice University, 6100 South Main Street, Houston, Texas 77005, USA. matsuda@rice.edu
S P
SP
Matsuda
L B
LB
Darr
E A
EA
Hart
J B
JB
Herrera
K E
KE
McCann
M M
MM
Meyer
J
J
Pang
H G
HG
Schepmann
D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D003500:Cyclization; D008401:Gas Chromatography-Mass Spectrometry; D019751:Intramolecular Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007810:Lanosterol / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D009154:Mutation; D010840:Phytosterols / Q000096:biosynthesis / Q000378:metabolism; D011522:Protons; D013329:Structure-Activity Relationship; D014315:Triterpenes
D010840:Phytosterols; D011522:Protons; D014315:Triterpenes; D007810:Lanosterol; D019751:Intramolecular Transferases; C021923:cycloartenol synthase; C100089:cycloartenol