cDNA Isolation and Functional Characterization of UDP-d-glucuronic Acid 4-Epimerase Family from Ornithogalum caudatum.
d-Galacturonic acid (GalA) is an important component of GalA-containing polysaccharides inOrnithogalum caudatum. The incorporation of GalA into these polysaccharides from UDP-d-galacturonic acid (UDP-GalA) was reasonably known. However, the cDNAs involved in the biosynthesis of UDP-GalA were still unknown. In the present investigation, one candidate UDP-d-glucuronic acid 4-epimerase (UGlcAE) family with three members was isolated fromO. caudatumbased on RNA-Seq data. Bioinformatics analyses indicated all of the three isoforms, designated as OcUGlcAE1~3, were members of short-chain dehydrogenases/reductases (SDRs) and shared two conserved motifs. The three full-length cDNAs were then transformed toPichia pastorisGS115 for heterologous expression. Data revealed both the supernatant and microsomal fractions from the recombinantP. pastorisexpressingOcUGlcAE3can interconvert UDP-GalA and UDP-d-glucuronic acid (UDP-GlcA), while the other two OcUGlcAEs had no activity on UDP-GlcA and UDP-GalA. Furthermore, expression analyses of the three epimerases in varied tissues ofO. caudatumwere performed by real-time quantitative PCR (RT-qPCR). Results indicatedOcUGlcAE3, together with the other twoOcUGlcAE-like genes, was root-specific, displaying highest expression in roots. OcUGlcAE3 was UDP-d-glucuronic acid 4-epimerase and thus deemed to be involved in the biosynthesis of root polysaccharides. Moreover,OcUGlcAE3was proposed to be environmentally induced.
State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China. senyin@126.com.
Sen
S
Yin
State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China. sunnyyujia@imm.ac.cn.
Yu-Jia
YJ
Sun
State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China. mingliu@imm.ac.cn.
Ming
M
Liu
State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China. lena699@163.com.
Li-Na
LN
Li
State Key Laboratory of Bioactive Substance and Function of Natural Medicines & Ministry of Health Key Laboratory of Biosynthesis of Natural Products, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China. jianqiangk@imm.ac.cn.
Jian-Qiang
JQ
Kong
D002238:Carbohydrate Epimerases / Q000096:biosynthesis / Q000235:genetics; D018076:DNA, Complementary; D015870:Gene Expression; D031442:Ornithogalum / Q000201:enzymology / Q000235:genetics; D010843:Pichia; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics; D014539:Uridine Diphosphate Sugars / Q000235:genetics / Q000378:metabolism
D018076:DNA, Complementary; D010940:Plant Proteins; D011994:Recombinant Proteins; D014539:Uridine Diphosphate Sugars; D002238:Carbohydrate Epimerases
">d-galacturonic acid; ">d-glucuronic acid; ">d-glucuronic acid 4-epimerase; Ornithogalum caudatum; UDP-; polysaccharides