Structural and Biochemical Characterization of Cinnamoyl-CoA Reductases

Journal Article · Mon Dec 12 00:00:00 EST 2016 · Plant Physiology (Bethesda)

DOI:https://doi.org/10.1104/pp.16.01671· OSTI ID:1661475

Sattler, Steven A.  ^[1]; Walker, Alexander M. ^[1]; Vermerris, Wilfred  ^[2]; Sattler, Scott E.  ^[3]; Kang, ChulHee  ^[1]

---

1. Washington State Univ., Pullman, WA (United States)
2. Washington State Univ., Pullman, WA (United States). Genetics Inst.
3. US Dept. of Agriculture (USDA), Lincoln, NE (United States). Agriculture-Agricultural Research Service, Grain Forage and Bioenergy Research Unit

Cinnamoyl-coenzyme A reductase (CCR) catalyzes the reduction of hydroxycinnamoyl-coenzyme A (CoA) esters using NADPH to produce hydroxycinnamyl aldehyde precursors in lignin synthesis. Here, the catalytic mechanism and substrate specificity of cinnamoyl-CoA reductases from sorghum (Sorghum bicolor), a strategic plant for bioenergy production, were deduced from crystal structures, site-directed mutagenesis, and kinetic and thermodynamic analyses. Although SbCCR1 displayed higher affinity for caffeoyl-CoA or p-coumaroyl-CoA than for feruloyl-CoA, the enzyme showed significantly higher activity for the latter substrate. Through molecular docking and comparisons between the crystal structures of the Vitis vinifera dihydroflavonol reductase and SbCCR1, residues threonine-154 and tyrosine-310 were pinpointed as being involved in binding CoA-conjugated phenylpropanoids. Threonine-154 of SbCCR1 and other CCRs likely confers strong substrate specificity for feruloyl-CoA over other cinnamoyl-CoA thioesters, and the T154Y mutation in SbCCR1 led to broader substrate specificity and faster turnover. Through data mining using our structural and biochemical information, four additional putative CCR genes were discovered from sorghum genomic data. One of these, SbCCR2, displayed greater activity toward p-coumaroyl-CoA than did SbCCR1, which could imply a role in the synthesis of defense-related lignin. Taken together, these findings provide knowledge about critical residues and substrate preference among CCRs and provide, to our knowledge, the first three-dimensional structure information for a CCR from a monocot species.

• Research Organization: Univ. of Florida, Gainesville, FL (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Transportation Office. Bioenergy Technologies Office; National Science Foundation (NSF); National Institutes of Health (NIH); M.J. Murdock Charitable Trust
• DOE Contract Number: PI0000031; MCB 102114; CHE 118359; 1231085; 1R01GM11125401; 2011-1006-30358; 2011- 67009-30026; 3042-21220-032-00D
• OSTI ID: 1661475
• Journal Information: Plant Physiology (Bethesda), Vol. 173, Issue 2; ISSN 0032-0889
• Publisher: American Society of Plant Biologists
• Country of Publication: United States
• Language: English