Protostadienol synthase from Aspergillus fumigatus: functional conversion into lanosterol synthase.
Biochem Biophys Res Commun
; 391(1): 899-902, 2010 Jan 01.
Article
em En
| MEDLINE
| ID: mdl-19951700
ABSTRACT
Oxidosqualeneprotostadienol cyclase (OSPC) from the fungus Aspergillus fumigatus, catalyzes the cyclization of (3S)-2,3-oxidosqualene into protosta-17(20)Z,24-dien-3beta-ol which is the precursor of the steroidal antibiotic helvolic acid. To shed light on the structure-function relationship between OSPC and oxidosqualenelanosterol cyclase (OSLC), we constructed an OSPC mutant in which the C-terminal residues (702)APPGGMR(708) were replaced with (702)NKSCAIS(708), as in human OSLC. As a result, the mutant no longer produced the protostadienol, but instead efficiently produced a 11 mixture of lanosterol and parkeol. This is the first report of the functional conversion of OSPC into OSLC, which resulted in a 14-fold decrease in the V(max)/K(M) value, whereas the binding affinity for the substrate did not change significantly. Homology modeling suggested that stabilization of the C-20 protosteryl cation by the active-site Phe701 through cation-pi interactions is important for the product outcome between protostadienol and lanosterol.
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1
Base de dados:
MEDLINE
Assunto principal:
Aspergillus fumigatus
/
Transferases Intramoleculares
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article