Post-translational and transcriptional regulation of phenylpropanoid biosynthesis pathway by Kelch repeat F-box protein SAGL1

• Published in: Plant molecular biology 2019-01, Vol.99 (1-2), p.135-148
• Main Authors: Yu, Si-in, Kim, Hyojin, Yun, Dae-Jin, Suh, Mi Chung, Lee, Byeong-ha
• Format: Article
• Language: English
• Subjects: Ammonia; Anthocyanins; Anthocyanins - metabolism; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biochemistry; Biomedical and Life Sciences; Biosynthesis; Cinnamic acid; Complementation; Enzymatic activity; F-box protein; F-Box Proteins - genetics; F-Box Proteins - metabolism; Fusion protein; Gene Expression; Gene Expression Profiling; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Plant; Gene regulation; Kelch Repeat; Life Sciences; Lignin; Lignin - metabolism; Metabolites; Mutation; Nicotiana - genetics; Nicotiana - metabolism; Oxygenases - genetics; Oxygenases - metabolism; Phenylalanine; Phenylalanine ammonia-lyase; Phenylalanine Ammonia-Lyase - genetics; Phenylalanine Ammonia-Lyase - metabolism; Phylogeny; Plant Pathology; Plant Sciences; Post-translation; Propanols - metabolism; Proteasomes; Proteins; Transcription; Translation
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1007/s11103-018-0808-8

Key message A Kelch repeat F-box containing protein, SMALL AND GLOSSY LEAVES1 ( SAGL1 ) regulates phenylpropanoid biosynthesis as a post-translational regulator for PAL1 (phenylalanine ammonia-lyase) and an indirect transcriptional regulator for ANTHOCYANIDIN SYNTHASE . Phenylpropanoid biosynthesis in plants produces diverse aromatic metabolites with important biological functions. Phenylalanine ammonia-lyase (PAL) catalyzes the first step in phenylpropanoid biosynthesis by converting l -phenylalanine to trans -cinnamic acid. Here, we report that SMALL AND GLOSSY LEAVES1 ( SAGL1 ), a Kelch repeat F-box protein, interacts with PAL1 protein for proteasome-mediated degradation to regulate phenylpropanoid biosynthesis in Arabidopsis . Mutations in SAGL1 caused high accumulation of anthocyanins and lignin derived from the phenylpropanoid biosynthesis pathway. We found that PAL enzyme activity increased in SAGL1-defective mutants, sagl1 , but decreased in SAGL1 -overexpressing Arabidopsis (SAGL1OE) without changes in the transcript levels of PAL genes, suggesting protein-level regulation by SAGL1. Indeed, the levels of PAL1-GFP fusion protein were reduced when both SAGL1 and PAL1-GFP were transiently co-expressed in leaves of Nicotiana benthamiana . In addition, bimolecular fluorescence complementation analysis suggested an interaction between SAGL1 and PAL1. We also found that the transcript levels of ANTHOCYANIDIN SYNTHASE ( ANS ) increased in the sagl1 mutants but decreased in SAGL1OE. Our results suggest that SAGL1 regulates phenylpropanoid biosynthesis post-translationally at PAL1 and transcriptionally at ANS .