Gibberellin-biosynthetic ent -kaurene synthases in higher plants do not require their non-catalytic domains for the catalysis

作者：So Oshikawa, Ayaka Naoe, Tomoka Moriya, Yuto Hasegawa, Momoko Nakasato, Yuga Ogawa, Hiroki Wakabayashi, Akira Itoh, Yuri Takeda, Sho Miyazaki, Hiroshi Kawaide, Tomonobu Toyomasu · 发表于：Biochemical Journal · 年份：2024 · DOI：10.1042/bcj20240162 · 被引用次数：8 · 研究领域：Plant biochemistry and biosynthesis、Sesquiterpenes and Asteraceae Studies、Bioactive Natural Diterpenoids Research

ent-Kaurene is a biosynthetic intermediate diterpene of phytohormone gibberellins, and is biosynthesized from geranylgeranyl diphosphate via ent-copalyl diphosphate (ent-CDP). The successive cyclization is catalyzed by two distinct diterpene synthases, ent-CDP synthase (ent-CPS) and ent-kaurene synthase (KS). Homologs of these diterpene synthase genes have been reported to be involved in the biosynthesis of specialized-metabolic diterpenoids for defense in several plant species, including rice (Oryza sativa). These diterpene synthases consist of three domains, αβγ domains. Active sites of ent-CPS exist at the interface of β and γ domain, while those of KS are located within the α domain. We herein carried out domain-deletion experiments using several KSs and KS like enzymes (KSLs) to obtain insights into the roles of domains other than active-site domains. As previously reported in taxadiene synthase, deletion of γ or βγ domains drastically decreased activities of specialized-metabolic OsKSL5, OsKSL8, OsKSL7 and OsKSL10 in O. sativa. However, unexpectedly, only α domains of several gibberellin-biosynthetic KSs, including OsKS1 in O. sativa, AtKS in Arabidopsis thaliana, TaKS in wheat (Triticum aestivum) and BdKS1 in Brachypodium distachyon, retained their original functions. Additionally, the specialized-metabolic OsKSL4, which is closely related to OsKS1, also functioned without its βγ domains. Domain-swapping experiments showed that replacing βγ domains in OsKSL7 with those...