| A novel red clover hydroxycinnamoyl transferase has enzymatic activities consistent with a role in phaselic acid biosynthesis. | |
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MedLine Citation:
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PMID: 19525325 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Red clover (Trifolium pratense) leaves accumulate several mumol g(-1) fresh weight of phaselic acid [2-O-(caffeoyl)-l-malate]. Postharvest oxidation of such o-diphenols to o-quinones by endogenous polyphenol oxidases prevents breakdown of forage protein during storage. Forage crops like alfalfa (Medicago sativa) lack both polyphenol oxidase and o-diphenols, and breakdown of their protein upon harvest and storage results in economic losses and release of excess nitrogen into the environment. Understanding how red clover synthesizes o-diphenols such as phaselic acid will help in the development of forage crops utilizing this natural system of protein protection. A possible pathway for phaselic acid biosynthesis predicts a hydroxycinnamoyl transferase (HCT) capable of forming caffeoyl and/or p-coumaroyl esters with malate. Genes encoding two distinct HCTs were identified in red clover. HCT1 shares more than 75% amino acid identity with a number of well-characterized shikimate O-HCTs implicated in monolignol biosynthesis. HCT2 shares only 34% amino acid sequence identity with HCT1 and has limited sequence identity to any previously identified HCT. Expression analyses indicate that HCT1 mRNA accumulates to 4-fold higher levels in stems than in leaves, whereas HCT2 mRNA accumulates to 10-fold higher levels in leaves than in stems. Activity assays of HCT1 and HCT2 proteins expressed in Escherichia coli indicate that HCT1 transfers caffeoyl or p-coumaroyl moieties from a coenzyme A-thiolester to shikimate but not malate, whereas HCT2 transfers caffeoyl or p-coumaroyl moieties from a coenzyme A-thiolester to malate but not shikimate. Together, these results indicate that HCT1 is involved in monolignol biosynthesis and HCT2 is a novel transferase likely involved in phaselic acid biosynthesis. |
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Authors:
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Michaell Sullivan |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. Date: 2009-06-12 |
Journal Detail:
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Title: Plant physiology Volume: 150 ISSN: 0032-0889 ISO Abbreviation: Plant Physiol. Publication Date: 2009 Aug |
Date Detail:
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Created Date: 2009-08-06 Completed Date: 2009-09-24 Revised Date: 2010-09-27 |
Medline Journal Info:
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Nlm Unique ID: 0401224 Medline TA: Plant Physiol Country: United States |
Other Details:
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Languages: eng Pagination: 1866-79 Citation Subset: IM |
Affiliation:
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Dairy Forage Research Center, Agricultural Research Service, United States Department of Agriculture, Madison, Wisconsin 53706, USA. michael.sullivan@ars.usda.gov |
| Data Bank Information | |
Bank Name/Acc. No.:
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GENBANK/EU861218; EU861219; FJ151489 |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Acyltransferases
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chemistry,
genetics,
metabolism* Amino Acid Sequence Caffeic Acids / chemistry, metabolism* Chromatography, High Pressure Liquid Cloning, Molecular Escherichia coli / metabolism Gene Expression Profiling Gene Expression Regulation, Plant Genes, Plant Hydrogen-Ion Concentration Malates / chemistry, metabolism* Metabolic Networks and Pathways Molecular Sequence Data Organ Specificity Shikimic Acid / metabolism Trifolium / enzymology*, genetics |
| Chemical | |
Reg. No./Substance:
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0/Caffeic Acids; 0/Malates; 0/phaselic acid; 138-59-0/Shikimic Acid; EC 2.3.-/Acyltransferases |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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