Cargando…
Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog
BACKGROUND: Down-regulation of the caffeic acid 3-O-methyltransferase EC 2.1.1.68 (COMT) gene in the lignin biosynthetic pathway of switchgrass (Panicum virgatum) resulted in cell walls of transgenic plants releasing more constituent sugars after pretreatment by dilute acid and treatment with glycos...
Autores principales: | , , , , , , , , , , , , , , , , |
---|---|
Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2012
|
Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3524654/ https://www.ncbi.nlm.nih.gov/pubmed/22998926 http://dx.doi.org/10.1186/1754-6834-5-71 |
_version_ | 1782253345939914752 |
---|---|
author | Tschaplinski, Timothy J Standaert, Robert F Engle, Nancy L Martin, Madhavi Z Sangha, Amandeep K Parks, Jerry M Smith, Jeremy C Samuel, Reichel Jiang, Nan Pu, Yunqiao Ragauskas, Arthur J Hamilton, Choo Y Fu, Chunxiang Wang, Zeng-Yu Davison, Brian H Dixon, Richard A Mielenz, Jonathan R |
author_facet | Tschaplinski, Timothy J Standaert, Robert F Engle, Nancy L Martin, Madhavi Z Sangha, Amandeep K Parks, Jerry M Smith, Jeremy C Samuel, Reichel Jiang, Nan Pu, Yunqiao Ragauskas, Arthur J Hamilton, Choo Y Fu, Chunxiang Wang, Zeng-Yu Davison, Brian H Dixon, Richard A Mielenz, Jonathan R |
author_sort | Tschaplinski, Timothy J |
collection | PubMed |
description | BACKGROUND: Down-regulation of the caffeic acid 3-O-methyltransferase EC 2.1.1.68 (COMT) gene in the lignin biosynthetic pathway of switchgrass (Panicum virgatum) resulted in cell walls of transgenic plants releasing more constituent sugars after pretreatment by dilute acid and treatment with glycosyl hydrolases from an added enzyme preparation and from Clostridium thermocellum. Fermentation of both wild-type and transgenic switchgrass after milder hot water pretreatment with no water washing showed that only the transgenic switchgrass inhibited C. thermocellum. Gas chromatography–mass spectrometry (GCMS)-based metabolomics were undertaken on cell wall aqueous extracts to determine the nature of the microbial inhibitors. RESULTS: GCMS confirmed the increased concentration of a number of phenolic acids and aldehydes that are known inhibitors of microbial fermentation. Metabolomic analyses of the transgenic biomass additionally revealed the presence of a novel monolignol-like metabolite, identified as trans-3, 4-dimethoxy-5-hydroxycinnamyl alcohol (iso-sinapyl alcohol) in both non-pretreated, as well as hot water pretreated samples. iso-Sinapyl alcohol and its glucoside were subsequently generated by organic synthesis and the identity of natural and synthetic materials were confirmed by mass spectrometric and NMR analyses. The additional novel presence of iso-sinapic acid, iso-sinapyl aldehyde, and iso-syringin suggest the increased activity of a para-methyltransferase, concomitant with the reduced COMT activity, a strict meta-methyltransferase. Quantum chemical calculations were used to predict the most likely homodimeric lignans generated from dehydration reactions, but these products were not evident in plant samples. CONCLUSIONS: Down-regulation of COMT activity in switchgrass resulted in the accumulation of previously undetected metabolites resembling sinapyl alcohol and its related metabolites, but that are derived from para-methylation of 5-hydroxyconiferyl alcohol, and related precursors and products; the accumulation of which suggests altered metabolism of 5-hydroxyconiferyl alcohol in switchgrass. Given that there was no indication that iso-sinapyl alcohol was integrated in cell walls, it is considered a monolignol analog. Diversion of substrates from sinapyl alcohol to free iso-sinapyl alcohol, its glucoside, and associated upstream lignin pathway changes, including increased phenolic aldehydes and acids, are together associated with more facile cell wall deconstruction, and to the observed inhibitory effect on microbial growth. However, iso-sinapyl alcohol and iso-sinapic acid, added separately to media, were not inhibitory to C. thermocellum cultures. |
format | Online Article Text |
id | pubmed-3524654 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2012 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-35246542013-01-08 Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog Tschaplinski, Timothy J Standaert, Robert F Engle, Nancy L Martin, Madhavi Z Sangha, Amandeep K Parks, Jerry M Smith, Jeremy C Samuel, Reichel Jiang, Nan Pu, Yunqiao Ragauskas, Arthur J Hamilton, Choo Y Fu, Chunxiang Wang, Zeng-Yu Davison, Brian H Dixon, Richard A Mielenz, Jonathan R Biotechnol Biofuels Research BACKGROUND: Down-regulation of the caffeic acid 3-O-methyltransferase EC 2.1.1.68 (COMT) gene in the lignin biosynthetic pathway of switchgrass (Panicum virgatum) resulted in cell walls of transgenic plants releasing more constituent sugars after pretreatment by dilute acid and treatment with glycosyl hydrolases from an added enzyme preparation and from Clostridium thermocellum. Fermentation of both wild-type and transgenic switchgrass after milder hot water pretreatment with no water washing showed that only the transgenic switchgrass inhibited C. thermocellum. Gas chromatography–mass spectrometry (GCMS)-based metabolomics were undertaken on cell wall aqueous extracts to determine the nature of the microbial inhibitors. RESULTS: GCMS confirmed the increased concentration of a number of phenolic acids and aldehydes that are known inhibitors of microbial fermentation. Metabolomic analyses of the transgenic biomass additionally revealed the presence of a novel monolignol-like metabolite, identified as trans-3, 4-dimethoxy-5-hydroxycinnamyl alcohol (iso-sinapyl alcohol) in both non-pretreated, as well as hot water pretreated samples. iso-Sinapyl alcohol and its glucoside were subsequently generated by organic synthesis and the identity of natural and synthetic materials were confirmed by mass spectrometric and NMR analyses. The additional novel presence of iso-sinapic acid, iso-sinapyl aldehyde, and iso-syringin suggest the increased activity of a para-methyltransferase, concomitant with the reduced COMT activity, a strict meta-methyltransferase. Quantum chemical calculations were used to predict the most likely homodimeric lignans generated from dehydration reactions, but these products were not evident in plant samples. CONCLUSIONS: Down-regulation of COMT activity in switchgrass resulted in the accumulation of previously undetected metabolites resembling sinapyl alcohol and its related metabolites, but that are derived from para-methylation of 5-hydroxyconiferyl alcohol, and related precursors and products; the accumulation of which suggests altered metabolism of 5-hydroxyconiferyl alcohol in switchgrass. Given that there was no indication that iso-sinapyl alcohol was integrated in cell walls, it is considered a monolignol analog. Diversion of substrates from sinapyl alcohol to free iso-sinapyl alcohol, its glucoside, and associated upstream lignin pathway changes, including increased phenolic aldehydes and acids, are together associated with more facile cell wall deconstruction, and to the observed inhibitory effect on microbial growth. However, iso-sinapyl alcohol and iso-sinapic acid, added separately to media, were not inhibitory to C. thermocellum cultures. BioMed Central 2012-09-21 /pmc/articles/PMC3524654/ /pubmed/22998926 http://dx.doi.org/10.1186/1754-6834-5-71 Text en Copyright ©2012 Tschaplinski et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Tschaplinski, Timothy J Standaert, Robert F Engle, Nancy L Martin, Madhavi Z Sangha, Amandeep K Parks, Jerry M Smith, Jeremy C Samuel, Reichel Jiang, Nan Pu, Yunqiao Ragauskas, Arthur J Hamilton, Choo Y Fu, Chunxiang Wang, Zeng-Yu Davison, Brian H Dixon, Richard A Mielenz, Jonathan R Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog |
title | Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog |
title_full | Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog |
title_fullStr | Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog |
title_full_unstemmed | Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog |
title_short | Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog |
title_sort | down-regulation of the caffeic acid o-methyltransferase gene in switchgrass reveals a novel monolignol analog |
topic | Research |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3524654/ https://www.ncbi.nlm.nih.gov/pubmed/22998926 http://dx.doi.org/10.1186/1754-6834-5-71 |
work_keys_str_mv | AT tschaplinskitimothyj downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT standaertrobertf downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT englenancyl downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT martinmadhaviz downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT sanghaamandeepk downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT parksjerrym downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT smithjeremyc downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT samuelreichel downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT jiangnan downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT puyunqiao downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT ragauskasarthurj downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT hamiltonchooy downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT fuchunxiang downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT wangzengyu downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT davisonbrianh downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT dixonricharda downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog AT mielenzjonathanr downregulationofthecaffeicacidomethyltransferasegeneinswitchgrassrevealsanovelmonolignolanalog |