A structural model of PpoA derived from SAXS-analysis-implications for substrate conversion.
Biochim Biophys Acta
; 1831(9): 1449-57, 2013 Sep.
Article
em En
| MEDLINE
| ID: mdl-23797010
ABSTRACT
In plants and mammals, oxylipins may be synthesized via multi step processes that consist of dioxygenation and isomerization of the intermediately formed hydroperoxy fatty acid. These processes are typically catalyzed by two distinct enzyme classes dioxygenases and cytochrome P450 enzymes. In ascomycetes biosynthesis of oxylipins may proceed by a similar two-step pathway. An important difference, however, is that both enzymatic activities may be combined in a single bifunctional enzyme. These types of enzymes are named Psi-factor producing oxygenases (Ppo). Here, the spatial organization of the two domains of PpoA from Aspergillus nidulans was analyzed by small-angle X-ray scattering and the obtained data show that the enzyme exhibits a relatively flat trimeric shape. Atomic structures of the single domains were obtained by template-based structure prediction and docked into the enzyme envelope of the low resolution structure obtained by SAXS. EPR-based distance measurements between the tyrosyl radicals formed in the activated dioxygenase domain of the enzyme supported the trimeric structure obtained from SAXS and the previous assignment of Tyr374 as radical-site in PpoA. Furthermore, two phenylalanine residues in the cytochrome P450 domain were shown to modulate the specificity of hydroperoxy fatty acid rearrangement.
Palavras-chave
AOS; Cytochrome P450; D(max); DEER; DES; DOX; DiHODE; DiHOME; Dioxygenase; Double electronelectron resonance; EPR; Et(2)O; H(P)ODE; HPL; KODE; KOME; LOX; MALDI-TOF; MW; Oxylipin; PGHS; PGIS; Ppo; Psi-factor producing oxygenase; R(g); SAXS; Small-angle X-ray scattering; TXAS; V(p); allene oxide synthase; diethyl ether; dihydroxy linoleic acid; dihydroxy oleic acid; dioxygenase; divinyl ether synthase; double electronelectron resonance; electron paramagnetic resonance; hydro(pero)xy linoleic acid; hydroperoxide lyase; lipoxygenase; matrix-assisted laser desorption/ionization-time of flight; maximal particle dimension; molecular weight; oxo-linoleic acid; oxo-oleic acid; particle volume; precocious sexual inducer; prostacyclin synthase; prostaglandin endoperoxide synthase; psi; psi-factor producing oxygenase; radius of gyration; small-angle X-ray scattering; thromboxane synthase
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Aspergillus nidulans
/
Sistema Enzimático do Citocromo P-450
/
Dioxigenases
/
Espalhamento a Baixo Ângulo
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
2013
Tipo de documento:
Article
País de afiliação:
Alemanha