Steric bulk at position 454 in Saccharomyces cerevisiae lanosterol synthase influences B-ring formation but not deprotonation.
[reaction: see text] Lanosterol synthase converts oxidosqualene to the tetracyclic sterol precursor lanosterol. The mutation experiments described here show that an active-site valine residue in lanosterol synthase contributes to cyclization control through steric effects. Mutating to smaller alanine or glycine residues allows formation of the monocyclic achilleol A, whereas the leucine and isoleucine mutants make exclusively lanosterol. The phenylalanine mutant is inactive.
Joubert
B M
BM
Department of Chemistry, Rice University, Houston, Texas 77005, USA.
Hua
L
L
Matsuda
S P
SP
D019943:Amino Acid Substitution; D001665:Binding Sites; D019751:Intramolecular Transferases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008861:Microsomes / Q000201:enzymology; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D011522:Protons; D012441:Saccharomyces cerevisiae / Q000201:enzymology*
D011522:Protons; D019751:Intramolecular Transferases; C021924:lanosterol synthase