An Ancient Relative of Cyclooxygenase in Cyanobacteria Is a Linoleate 10S-Dioxygenase That Works in Tandem with a Catalase-related Protein with Specific 10S-Hydroperoxide Lyase Activity

Abstract

Background: Fatty acid heme dioxygenases occur in eukaryotes, often associated with a cytochrome P450 that transforms the peroxide product. Results: Neighboring cyanobacterial genes, dioxygenase and catalase, are identified as linoleate 10S-dioxygenase and 10S-hydroperoxide lyase, respectively. Conclusion: These Nostoc hemoproteins show novel activities. Significance: Our results identify a heme dioxygenase ancestor and a catalase that substitutes in function for a cytochrome P450.

Bacterial and algal orthologs of prostaglandin H2 synthase: novel insights into the evolution of an integral membrane protein

“…Unfortunately, there are no available high-resolution structures of members within this group that directly reveal their structural properties. As aforementioned, the enzyme from Nostoc punctiforme was recently expressed and characterized as a 10S-dioxygenase [21]. The dioxygenase is proposed to work in tandem with an upstream ORF for a catalase that converts the 10S hydroperoxide product of the dioxygenase enzyme to the corresponding alcohol.…”

“…The dioxygenase is proposed to work in tandem with an upstream ORF for a catalase that converts the 10S hydroperoxide product of the dioxygenase enzyme to the corresponding alcohol. Notably, the recombinant Nostoc enzyme can be expressed and isolated as a soluble enzyme, in contrast to eukaryotic counterparts that require detergent for solubilization [21].…”

“…In the only algal ortholog characterized in vitro, the recombinant protein ably converts arachidonic acid to PGG 2 and PGH 2 , but behaves as a tetramer by size-exclusion chromatography [22]. In the only bacterial ortholog characterized to date, the cyanobacterial 'cyclooxygenase' (actually characterized as a dioxygenase) identified from Nostoc punctiforme is proposed to work in tandem with a neighboring upstream fatty acid heme hydroperoxide lyase gene rather than provide two distinct activities, and shows strong preference for oleic and linoleic acid over arachidonic acid [21]. While the recombinant algal protein required detergent for solubility, the bacterial protein did not.…”

“…Assignment of these many orthologs to the peroxidase-cyclooxygenase superfamily is based largely on sequence relationships [20]; only most recently have select orthologs been characterized in vitro to directly assess this relationship [21,22]. While the endoplasmic reticulum is common to all eukaryotic organisms, the presence of PGHS orthologs in lower organisms invokes a number of intuitive questions regarding evolution, structure, and function.…”

A Catalase-related Hemoprotein in Coral Is Specialized for Synthesis of Short-chain Aldehydes

“…The amplicons of fusion protein b and the catalase-related domain were cloned into the pET11a expression vector (Stratagene) and sequenced. The His-tagged fusion protein b and catalase-related domain were expressed in E. coli BL21(DE3) cells (Novagen) in a Terrific Broth medium at 20°C overnight and purified as described previously (17). The protein fractions were dialyzed against an ice-cold 50 mM Tris (pH 8.0) buffer containing 100 mM NaCl by slowly stirring overnight at 4°C.…”