PDBsum entry 1u5u

Lyase

PDB id: 1u5u

Contents

Protein chains

366 a.a. *

Ligands

HEM ×2

Waters ×569

* Residue conservation analysis

PDB id:

1u5u

Name:

Lyase

Title:

The structure of an allene oxide synthase reveals a novel use for a catalase fold

Structure:

Allene oxide synthase-lipoxygenase protein. Chain: a, b. Fragment: allene oxide synthase domain. Engineered: yes

Source:

Plexaura homomalla. Organism_taxid: 47982. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

2.00Å R-factor: 0.196 R-free: 0.239

Authors:

M.L.Oldham,A.R.Brash,M.E.Newcomer

Key ref:

M.L.Oldham et al. (2005). The structure of coral allene oxide synthase reveals a catalase adapted for metabolism of a fatty acid hydroperoxide. Proc Natl Acad Sci U S A, 102, 297-302. PubMed id: 15625113 DOI: 10.1073/pnas.0406352102

Date:

28-Jul-04 Release date: 11-Jan-05

Protein chains

O16025  (AOSL_PLEHO) -  Allene oxide synthase-lipoxygenase protein from Plexaura homomalla

Seq: 1066 a.a.

Struc: 366 a.a.

Enzyme reactions

• Enzyme class 2: E.C.1.13.11.40 - arachidonate 8-lipoxygenase.
• Reaction: (5Z,8Z,11Z,14Z)-eicosatetraenoate + O2 = (8R)-hydroperoxy- (5Z,9E,11Z,14Z)-eicosatetraenoate
• Cofactor: Fe cation
• Enzyme class 3: E.C.4.2.1.- - ?????

Note, where more than one E.C. class is given (as above), each may correspond to a different protein domain or, in the case of polyprotein precursors, to a different mature protein.

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Key reference

DOI no: 10.1073/pnas.0406352102

Proc Natl Acad Sci U S A 102:297-302 (2005)

PubMed id: 15625113

The structure of coral allene oxide synthase reveals a catalase adapted for metabolism of a fatty acid hydroperoxide.

M.L.Oldham, A.R.Brash, M.E.Newcomer.

ABSTRACT

8R-Lipoxygenase and allene oxide synthase (AOS) are parts of a naturally occurring fusion protein from the coral Plexaura homomalla. AOS catalyses the production of an unstable epoxide (an allene oxide) from the fatty acid hydroperoxide generated by the lipoxygenase activity. Here, we report the structure of the AOS domain and its striking structural homology to catalase. Whereas nominal sequence identity between the enzymes had been previously described, the extent of structural homology observed was not anticipated, given that this enzyme activity had been exclusively associated with the P450 superfamily, and conservation of a catalase fold without catalase activity is unprecedented. Whereas the heme environment is largely conserved, the AOS heme is planar and the distal histidine is flanked by two hydrogen-bonding residues. These critical differences likely facilitate the switch from a catalatic activity to that of a fatty acid hydroperoxidase.

Selected figure(s)

Figure 1.
Fig. 1. Comparison of allene oxide biosynthesis in coral and plants. The conversion of allene oxide to clavulone remains unproven.

Figure 3.
Fig. 3. Comparison of AOS and catalase. (a) Superimposition of AOS (green; heme is red) with HEC (gray; heme is blue). The catalase N-terminal threading arm and wrapping domains are indicated. (b) Superposition of the heme environments of AOS (green carbons) and catalase (gray carbons). Dashed lines indicating active-site hydrogen bonds are black (AOS) and pink (HEC), respectively.

Figures were selected by the author.