Journal article
The Enzyme Activity and Substrate Specificity of Two Major Cinnamyl Alcohol Dehydrogenases in Sorghum ( Sorghum bicolor ), SbCAD2 and SbCAD4
Plant physiology (Bethesda), Vol.174(4), pp.2128-2145
08/2017
Handle:
https://hdl.handle.net/2376/103817
PMID: 28606901
Abstract
Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step in monolignol biosynthesis, reducing sinapaldehyde, coniferaldehyde, and
-coumaraldehyde to their corresponding alcohols in an NADPH-dependent manner. Because of its terminal location in monolignol biosynthesis, the variation in substrate specificity and activity of CAD can result in significant changes in overall composition and amount of lignin. Our in-depth characterization of two major CAD isoforms, SbCAD2 (Brown midrib 6 [bmr6]) and SbCAD4, in lignifying tissues of sorghum (
), a strategic plant for generating renewable chemicals and fuels, indicates their similarity in both structure and activity to Arabidopsis (
) CAD5 and
sinapyl alcohol dehydrogenase, respectively. This first crystal structure of a monocot CAD combined with enzyme kinetic data and a catalytic model supported by site-directed mutagenesis allows full comparison with dicot CADs and elucidates the potential signature sequence for their substrate specificity and activity. The L119W/G301F-SbCAD4 double mutant displayed its substrate preference in the order coniferaldehyde >
-coumaraldehyde > sinapaldehyde, with higher catalytic efficiency than that of both wild-type SbCAD4 and SbCAD2. As SbCAD4 is the only major CAD isoform in
mutants, replacing SbCAD4 with L119W/G301F-SbCAD4 in
plants could produce a phenotype that is more amenable to biomass processing.
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Details
- Title
- The Enzyme Activity and Substrate Specificity of Two Major Cinnamyl Alcohol Dehydrogenases in Sorghum ( Sorghum bicolor ), SbCAD2 and SbCAD4
- Creators
- Se-Young Jun - Department of Chemistry, Washington State University, Pullman, Washington 99164Alexander M Walker - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164Hoon Kim - Department of Biochemistry and Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin 53726John Ralph - Department of Biochemistry and Department of Energy Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, Wisconsin 53726Wilfred Vermerris - University of Florida, Genetics Institute, Gainesville, Florida 32610Scott E Sattler - United States Department of Agriculture-Agricultural Research Service, Wheat, Sorghum, and Forage Research Unit, Lincoln, Nebraska 68583ChulHee Kang - School of Molecular Biosciences, Washington State University, Pullman, Washington 99164
- Publication Details
- Plant physiology (Bethesda), Vol.174(4), pp.2128-2145
- Academic Unit
- Chemistry, Department of
- Publisher
- United States
- Grant note
- R01 GM111254 / NIGMS NIH HHS
- Identifiers
- 99900546663701842
- Language
- English
- Resource Type
- Journal article