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

Authors :
So Oshikawa
Ayaka Naoe
Tomoka Moriya
Yuto Hasegawa
Momoko Nakasato
Yuga Ogawa
Hiroki Wakabayashi
Akira Itoh
Yuri Takeda-Kimura
Sho Miyazaki
Hiroshi Kawaide Tomonobu Toyomasu
Source :
Biochemical Journal; Jun2024, Vol. 481 Issue 12, p779-791, 13p
Publication Year :
2024

Abstract

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 from other KS/KSLs retained the OsKSL7 activity. Moreover, deletion of βγ domains of bifunctional PpCPS/KS in moss (Physcomitrella patens) drastically impaired its KS-related activity. Thus, we demonstrate that monofunctional gibberellinbiosynthetic KSs are the unique diterpene synthases that retain their functions without βγ domains. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
02646021
Volume :
481
Issue :
12
Database :
Complementary Index
Journal :
Biochemical Journal
Publication Type :
Academic Journal
Accession number :
178268977
Full Text :
https://doi.org/10.1042/bcj20240162