A plastid envelope location of Arabidopsis ent-kaurene oxidase links the plastid and endoplasmic reticulum steps of the gibberellin biosynthesis pathway

Helliwell, CA Sullivan, JA Mould, RM Gray, JC Peacock, WJ Dennis, ES

Ca. Helliwell et al., A plastid envelope location of Arabidopsis ent-kaurene oxidase links the plastid and endoplasmic reticulum steps of the gibberellin biosynthesis pathway, PLANT J, 28(2), 2001, pp. 201-208

29

INGLESE

Article

Plant Sciences","Animal & Plant Sciences

PLANT JOURNAL

0960-7412 → ACNP

28

2

2001

201 - 208

ISI

0960-7412(200110)28:2<201:APELOA>2.0.ZU;2-K

We have used fusions of gibberellin biosynthesis enzymes to green fluoresce nt protein (GFP) to determine the subcellular localization of the early ste ps of the pathway. Gibberellin biosynthesis from geranylgeranyl diphosphate is catalysed by enzymes of the terpene cyclase, cytochrome P450 monooxygen ase and 2-oxoglutarate-dependent dioxygenase classes. We show that the N-te rminal presequences of the Arabidopsis thaliana terpene cyclases copalyl di phosphate synthase (AtCPS1) and entkaurene synthase (AtKS1) direct GFP to c hloroplasts; in transient assays following microprojectile bombardment of t obacco leaves. The AtKS1-GFP fusion is also imported by isolated pea chloro plasts. The N-terminal portion of the cytochrome P450 protein ent-kaurene o xidase (AtKO1) directs GFP to chloroplasts in tobacco leaf transient assays , Chloroplast import assays with S-35-labelled AtKO1 protein show that it i s targeted to the outer face of the chloroplast envelope. The leader sequen ces of the two ent-kaurenoic acid oxidases (AtKAO1 and AtKAO2) from Arabido psis direct GFP to the endoplasmic reticulum. These data suggest that the A tKO1 protein links the plastid- and endoplasmic reticulum-located steps of the gibberellin biosynthesis pathway by association with the outer envelope of the plastid.