Biochemical characterization and identification of a cinnamyl alcohol dehydrogenase from Artemisia annua.
It is well known in the literature that cinnamyl alcohol dehydrogenase (CAD) reduces hydroxycinnamyl aldehydes, such as coumaryl, coniferyl, and sinapyl aldehydes, to their corresponding alcohols in the presence of NADPH, and these alcohols act as the precursors of lignin biosynthesis. Here, we report the isolation of a cDNA encoding an NADP(+)-dependent CAD, designated as AaCAD, from the cDNA library using glandular secretory trichomes of Artemisia annua as the source of mRNA. A phylogenetic analysis indicated that AaCAD was clustered with AtCAD4 and AtCAD5, which were involved in monolignol biosynthesis from Arabidopsis. Semi-quantitative RT-PCR showed that the AaCAD transcript was abundant mostly in leaf and root, followed by flower, and lowest in stem. Functional and enzymatic assays showed that the recombinant enzyme was able to reversibly reduce a variety of common CADs substrates, namely geranial, cinnamyl aldehyde, sinapyl aldehyde, coniferyl aldehyde, and a sesquiterpenoid artemisinic aldehyde, to geraniol, cinnamyl alcohol, sinapyl alcohol, coniferyl alcohol, and artemisinic alcohol respectively. Besides, considering that AaCAD was identified from the glandular secretory trichomes of A. annua, and that the recombinant enzyme exhibited reductase activity by using artemisinic aldehyde as substrate, some possible role of AaCAD in artemisinin biosynthesis is also discussed.
Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
Xing
X
Li
Graduate University of Chinese Academy of Sciences, Beijing 100049, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, 100093 Beijing, China.
Dongming
D
Ma
Graduate University of Chinese Academy of Sciences, Beijing 100049, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, 100093 Beijing, China.
Jianlin
J
Chen
Shandong Yingcai University, 250104 Jinan, China.
Gaobin
G
Pu
Graduate University of Chinese Academy of Sciences, Beijing 100049, China.
Yunpeng
Y
Ji
College of Plant Protection, Henan Agricultural University, 450002 Zhengzhou, China.
Caiyan
C
Lei
Key Laboratory of Plant Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, 100093 Beijing, China.
Zhigao
Z
Du
Key Laboratory of Plant Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, 100093 Beijing, China.
Benye
B
Liu
Key Laboratory of Plant Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, 100093 Beijing, China.
Hechun
H
Ye
Graduate University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: hwang@gucas.ac.cn.
Hong
H
Wang
D000429:Alcohol Oxidoreductases / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics*; D000447:Aldehydes / Q000378:metabolism; D031172:Artemisia annua / Q000201:enzymology* / Q000235:genetics*; D037621:Artemisinins / Q000378:metabolism; D035264:Flowers / Q000201:enzymology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007783:Lactones / Q000378:metabolism; D008969:Molecular Sequence Data; D010937:Plant Growth Regulators / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics*; D018515:Plant Leaves / Q000201:enzymology; D018517:Plant Roots / Q000201:enzymology; D018547:Plant Stems / Q000201:enzymology; D030821:Plants, Genetically Modified / Q000201:enzymology
D000447:Aldehydes; D037621:Artemisinins; D007783:Lactones; D010937:Plant Growth Regulators; D000429:Alcohol Oxidoreductases; C018656:cinnamyl alcohol dehydrogenase; C075875:artemisin