Structural Evidence for the Substrate Channeling of Rice Allene Oxide Cyclase in Biologically Analogous Nazarov Reaction

Frontiers in Chemistry

Kyoungwon Cho¹  Oksoo Han¹  Sereyvath Yoeun² 

[1] Department of Molecular Biotechnology and Kumho Life Science Laboratory, College of Agriculture and Life Sciences, Chonnam National University, Gwangju, South Korea;Faculty of Chemical and Food Engineering, Institute of Technology of Cambodia, Phnom Penh, Cambodia;

关键词: allene oxide cyclase;    rice;    nazarov reaction;    octadecanoid;    oxylipin;    jasmonic acid;   

DOI  :  10.3389/fchem.2018.00500

来源: DOAJ

【 摘 要 】

Allene oxide cyclase (AOC) is a key enzyme in the jasmonic acid (JA) biosynthetic pathway in plants, during which it catalyzes stereospecific conversion of 12,13(S)-epoxy-9(Z),11,15(Z)-octadecatrienoic acid (12,13-EOT) to cis(+)-12-oxophytodienoic acid. Here, rice allene oxide cyclase (OsAOC) was localized to the chloroplast and its native oligomeric structure was analyzed by gel electrophoresis in the absence and presence of a protein-crosslinking reagent. The results suggest that OsAOC exists in solution as a mixture of monomers, dimers, and higher order multimers. OsAOC preferentially exists as dimer at room temperature, but it undergoes temperature-dependent partial denaturation in the presence of SDS. A heteromeric 2:1 complex of OsAOC and rice allene oxide synthase-1 (OsAOS1) was detected after cross-linking. The yield of cis(+)-12-oxophytodienoic acid reached maximal saturation at a 5:1 molar ratio of OsAOC to OsAOS1, when OsAOC and OsAOS1 reactions were coupled. These results suggest that the OsAOC dimer may facilitate its interaction with OsAOS1, and that the heteromeric 2:1 complex may promote efficient channeling of the unstable allene oxide intermediate during catalysis. In addition, conceptual similarities between the reaction catalyzed by AOC and Nazarov cyclization are discussed.

【 授权许可】

Unknown