PDBsum entry 3dy5

Lyase, oxidoreductase

PDB id: 3dy5

Contents

Protein chains

1002 a.a.

Ligands

HEM ×2

Metals

FE2 ×2

References listed in PDB file

Key reference

• Title: A covalent linker allows for membrane targeting of an oxylipin biosynthetic complex.
• Authors: N.C.Gilbert, M.Niebuhr, H.Tsuruta, T.Bordelon, O.Ridderbusch, A.Dassey, A.R.Brash, S.G.Bartlett, M.E.Newcomer.
• Ref.: Biochemistry, 2008, 47, 10665-10676.
• PubMed id: 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.