Document Detail

An engineered monolignol 4-o-methyltransferase depresses lignin biosynthesis and confers novel metabolic capability in Arabidopsis.
MedLine Citation:
PMID:  22851762     Owner:  NLM     Status:  MEDLINE    
Although the practice of protein engineering is industrially fruitful in creating biocatalysts and therapeutic proteins, applications of analogous techniques in the field of plant metabolic engineering are still in their infancy. Lignins are aromatic natural polymers derived from the oxidative polymerization of primarily three different hydroxycinnamyl alcohols, the monolignols. Polymerization of lignin starts with the oxidation of monolignols, followed by endwise cross-coupling of (radicals of) a monolignol and the growing oligomer/polymer. The para-hydroxyl of each monolignol is crucial for radical generation and subsequent coupling. Here, we describe the structure-function analysis and catalytic improvement of an artificial monolignol 4-O-methyltransferase created by iterative saturation mutagenesis and its use in modulating lignin and phenylpropanoid biosynthesis. We show that expressing the created enzyme in planta, thus etherifying the para-hydroxyls of lignin monomeric precursors, denies the derived monolignols any participation in the subsequent coupling process, substantially reducing lignification and, ultimately, lignin content. Concomitantly, the transgenic plants accumulated de novo synthesized 4-O-methylated soluble phenolics and wall-bound esters. The lower lignin levels of transgenic plants resulted in higher saccharification yields. Our study, through a structure-based protein engineering approach, offers a novel strategy for modulating phenylpropanoid/lignin biosynthesis to improve cell wall digestibility and diversify the repertories of biologically active compounds.
Kewei Zhang; Mohammad-Wadud Bhuiya; Jorge Rencoret Pazo; Yuchen Miao; Hoon Kim; John Ralph; Chang-Jun Liu
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-07-31
Journal Detail:
Title:  The Plant cell     Volume:  24     ISSN:  1532-298X     ISO Abbreviation:  Plant Cell     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-08-24     Completed Date:  2013-02-14     Revised Date:  2013-07-12    
Medline Journal Info:
Nlm Unique ID:  9208688     Medline TA:  Plant Cell     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3135-52     Citation Subset:  IM    
Department of Biology, Brookhaven National Laboratory, Upton, NY 11973, USA.
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MeSH Terms
Arabidopsis / enzymology,  genetics,  growth & development,  metabolism*
Cell Wall / chemistry,  metabolism
Gene Expression
Genetic Engineering
Lignin / biosynthesis*
Methyltransferases / genetics*,  metabolism
Models, Molecular
Mutant Proteins / genetics,  metabolism
Phenols / metabolism*
Plant Proteins / genetics,  metabolism
Plants, Genetically Modified
Propanols / metabolism
Recombinant Proteins
Structure-Activity Relationship
Substrate Specificity
Reg. No./Substance:
0/Mutant Proteins; 0/Phenols; 0/Plant Proteins; 0/Propanols; 0/Recombinant Proteins; 0F897O3O4M/1-phenylpropanol; 9005-53-2/Lignin; E7SM92591P/coniferyl alcohol; EC 2.1.1.-/Methyltransferases

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