A covalent linker allows for membrane targeting of an oxylipin biosynthetic complex.
Biochemistry
; 47(40): 10665-76, 2008 Oct 07.
Article
em En
| MEDLINE
| ID: mdl-18785758
ABSTRACT
A naturally occurring bifunctional protein from Plexaura homomalla links sequential catalytic activities in an oxylipin biosynthetic pathway. The C-terminal lipoxygenase (LOX) portion of the molecule catalyzes the transformation of arachidonic acid (AA) to the corresponding 8 R-hydroperoxide, and the N-terminal allene oxide synthase (AOS) domain promotes the conversion of the hydroperoxide intermediate to the product allene oxide (AO). Small-angle X-ray scattering data indicate that in the absence of a covalent linkage the two catalytic domains that transform AA to AO associate to form a complex that recapitulates the structure of the bifunctional protein. The SAXS data also support a model for LOX and AOS domain orientation in the fusion protein inferred from a low-resolution crystal structure. However, results of membrane binding experiments indicate that covalent linkage of the domains is required for Ca (2+)-dependent membrane targeting of the sequential activities, despite the noncovalent domain association. Furthermore, membrane targeting is accompanied by a conformational change as monitored by specific proteolysis of the linker that joins the AOS and LOX domains. Our data are consistent with a model in which Ca (2+)-dependent membrane binding relieves the noncovalent interactions between the AOS and LOX domains and suggests that the C2-like domain of LOX mediates both protein-protein and protein-membrane interactions.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas Recombinantes de Fusão
/
Lipoxigenase
/
Oxirredutases Intramoleculares
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article