Riboflavin Accumulation and Characterization of cDNAs Encoding Lumazine Synthase and Riboflavin Synthase in Bitter Melon (Momordica charantia)

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• 作者：Pham Anh Tuan ; Jae Kwang Kim ; Sanghyun Lee ; Soo Cheon Chae ; Sang Un Park
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2012
• 出版时间：December 5, 2012
• 年：2012
• 卷：60
• 期：48
• 页码：11980-11986
• 全文大小：485K
• 年卷期：v.60,no.48(December 5, 2012)
• ISSN：1520-5118

文摘

Riboflavin (vitamin B₂) is the universal precursor of the coenzymes flavin mononucleotide and flavin adenine dinucleotide鈥攃ofactors that are essential for the activity of a wide variety of metabolic enzymes in animals, plants, and microbes. Using the RACE PCR approach, cDNAs encoding lumazine synthase (McLS) and riboflavin synthase (McRS), which catalyze the last two steps in the riboflavin biosynthetic pathway, were cloned from bitter melon (Momordica charantia), a popular vegetable crop in Asia. Amino acid sequence alignments indicated that McLS and McRS share high sequence identity with other orthologous genes and carry an N-terminal extension, which is reported to be a plastid-targeting sequence. Organ expression analysis using quantitative real-time RT PCR showed that McLS and McRS were constitutively expressed in M. charantia, with the strongest expression levels observed during the last stage of fruit ripening (stage 6). This correlated with the highest level of riboflavin content, which was detected during ripening stage 6 by HPLC analysis. McLS and McRS were highly expressed in the young leaves and flowers, whereas roots exhibited the highest accumulation of riboflavin. The cloning and characterization of McLS and McRS from M. charantia may aid the metabolic engineering of vitamin B₂ in crops.

Keywords:

vitamin B₂; lumazine synthase; riboflavin synthase; cloning; characterization; Momordica charantia