Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation
Flavonols, phenylalanine-derived secondary metabolites, have protective and regulatory functions in plants. In Arabidopsis thaliana, they are consecutively glycosylated at their 3-OH and 7-OH groups. UGT78D1 and UGT78D2 are the major flavonol 3-O-glycosyltransferases in Arabidopsis leaves. The ugt78...
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Oxford University Press
2012
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| Online Access: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3346215/ |
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pubmed-33462152012-05-07 Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation Yin, Ruohe Messner, Burkhard Faus-Kessler, Theresa Hoffmann, Thomas Schwab, Wilfried Hajirezaei, Mohammad-Reza von Saint Paul, Veronica Heller, Werner Schäffner, Anton R. Research Papers Flavonols, phenylalanine-derived secondary metabolites, have protective and regulatory functions in plants. In Arabidopsis thaliana, they are consecutively glycosylated at their 3-OH and 7-OH groups. UGT78D1 and UGT78D2 are the major flavonol 3-O-glycosyltransferases in Arabidopsis leaves. The ugt78d1 ugt78d2 double mutant, which was strongly compromised in the initial 3-O-glycosylation, showed a severe and specific repression of flavonol biosynthesis, retaining only one-third of the wild-type level. This metabolic phenotype was associated with a repressed transcription of several flavonol biosynthetic genes including the committed step chalcone synthase [(CHS) or TRANSPARENT TESTA 4 (TT4)]. Furthermore, the committed step of the upstream, general phenylpropanoid pathway, phenylalanine ammonia-lyase (PAL), was down-regulated in its enzyme activity and in the transcription of the flavonol-related PAL1 and PAL2. However, a complete blocking of flavonoid biosynthesis at CHS released PAL inhibition in a tt4 ugt78d1 ugt78d2 line. PAL activity was even enhanced in the flavonol synthase 1 mutant, which compromises the final formation of flavonol aglycones. The dependence of the PAL feedback inhibition on flavonols was confirmed by chemical complementation of tt4 ugt78d1 ugt78d2 using naringenin, a downstream flavonoid intermediate, which restored the PAL repression. Although aglycones were not analytically detectable, this study provides genetic evidence for a novel, flavonol-dependent feedback inhibition of the flavonol biosynthetic pathway and PAL. It was conditioned by the compromised flavonol-3-O-conjugation and a decrease in flavonol content, yet dependent on a residual, flavonol synthase 1 (FLS1)-related capacity to form flavonol aglycones. Thus, this regulation would not react to a reduced metabolic flux into flavonol biosynthesis, but it might prevent the accumulation of non-glycosylated, toxic flavonols. Oxford University Press 2012-04 2012-01-16 /pmc/articles/PMC3346215/ /pubmed/22249996 http://dx.doi.org/10.1093/jxb/err416 Text en © 2012 The Author(s). http://creativecommons.org/licenses/by-nc/3.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details) |
| repository_type |
Open Access Journal |
| institution_category |
Foreign Institution |
| institution |
US National Center for Biotechnology Information |
| building |
NCBI PubMed |
| collection |
Online Access |
| language |
English |
| format |
Online |
| author |
Yin, Ruohe Messner, Burkhard Faus-Kessler, Theresa Hoffmann, Thomas Schwab, Wilfried Hajirezaei, Mohammad-Reza von Saint Paul, Veronica Heller, Werner Schäffner, Anton R. |
| spellingShingle |
Yin, Ruohe Messner, Burkhard Faus-Kessler, Theresa Hoffmann, Thomas Schwab, Wilfried Hajirezaei, Mohammad-Reza von Saint Paul, Veronica Heller, Werner Schäffner, Anton R. Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation |
| author_facet |
Yin, Ruohe Messner, Burkhard Faus-Kessler, Theresa Hoffmann, Thomas Schwab, Wilfried Hajirezaei, Mohammad-Reza von Saint Paul, Veronica Heller, Werner Schäffner, Anton R. |
| author_sort |
Yin, Ruohe |
| title |
Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation |
| title_short |
Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation |
| title_full |
Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation |
| title_fullStr |
Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation |
| title_full_unstemmed |
Feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-O-glycosylation |
| title_sort |
feedback inhibition of the general phenylpropanoid and flavonol biosynthetic pathways upon a compromised flavonol-3-o-glycosylation |
| description |
Flavonols, phenylalanine-derived secondary metabolites, have protective and regulatory functions in plants. In Arabidopsis thaliana, they are consecutively glycosylated at their 3-OH and 7-OH groups. UGT78D1 and UGT78D2 are the major flavonol 3-O-glycosyltransferases in Arabidopsis leaves. The ugt78d1 ugt78d2 double mutant, which was strongly compromised in the initial 3-O-glycosylation, showed a severe and specific repression of flavonol biosynthesis, retaining only one-third of the wild-type level. This metabolic phenotype was associated with a repressed transcription of several flavonol biosynthetic genes including the committed step chalcone synthase [(CHS) or TRANSPARENT TESTA 4 (TT4)]. Furthermore, the committed step of the upstream, general phenylpropanoid pathway, phenylalanine ammonia-lyase (PAL), was down-regulated in its enzyme activity and in the transcription of the flavonol-related PAL1 and PAL2. However, a complete blocking of flavonoid biosynthesis at CHS released PAL inhibition in a tt4 ugt78d1 ugt78d2 line. PAL activity was even enhanced in the flavonol synthase 1 mutant, which compromises the final formation of flavonol aglycones. The dependence of the PAL feedback inhibition on flavonols was confirmed by chemical complementation of tt4 ugt78d1 ugt78d2 using naringenin, a downstream flavonoid intermediate, which restored the PAL repression. Although aglycones were not analytically detectable, this study provides genetic evidence for a novel, flavonol-dependent feedback inhibition of the flavonol biosynthetic pathway and PAL. It was conditioned by the compromised flavonol-3-O-conjugation and a decrease in flavonol content, yet dependent on a residual, flavonol synthase 1 (FLS1)-related capacity to form flavonol aglycones. Thus, this regulation would not react to a reduced metabolic flux into flavonol biosynthesis, but it might prevent the accumulation of non-glycosylated, toxic flavonols. |
| publisher |
Oxford University Press |
| publishDate |
2012 |
| url |
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3346215/ |
| _version_ |
1611527901040082944 |