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Title: KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis

Abstract

Humans are unable to synthesize L-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity.

Authors:
 [1];  [1]; ORCiD logo [2];  [3];  [1];  [4];  [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [5]
  1. Saitama Univ. (Japan)
  2. Univ. of Cambridge (United Kingdom); RIKEN Center for Sustainable Resource Science, Yokohama (Japan); Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States)
  3. Joint BioEnergy Inst. (JBEI), Emeryville, CA (United States)
  4. Univ. of Cambridge (United Kingdom)
  5. Saitama Univ. (Japan); Univ. of Cambridge (United Kingdom)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1436989
DOE Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Plant Cell
Additional Journal Information:
Journal Volume: 27; Journal Issue: 12; Journal ID: ISSN 1040-4651
Publisher:
American Society of Plant Biologists
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Sawake, Shota, Tajima, Noriaki, Mortimer, Jenny C., Lao, Jeemeng, Ishikawa, Toshiki, Yu, Xiaolan, Yamanashi, Yukiko, Yoshimi, Yoshihisa, Kawai-Yamada, Maki, Dupree, Paul, Tsumuraya, Yoichi, and Kotake, Toshihisa. KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis. United States: N. p., 2015. Web. doi:10.1105/tpc.15.00379.
Sawake, Shota, Tajima, Noriaki, Mortimer, Jenny C., Lao, Jeemeng, Ishikawa, Toshiki, Yu, Xiaolan, Yamanashi, Yukiko, Yoshimi, Yoshihisa, Kawai-Yamada, Maki, Dupree, Paul, Tsumuraya, Yoichi, & Kotake, Toshihisa. KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis. United States. doi:10.1105/tpc.15.00379.
Sawake, Shota, Tajima, Noriaki, Mortimer, Jenny C., Lao, Jeemeng, Ishikawa, Toshiki, Yu, Xiaolan, Yamanashi, Yukiko, Yoshimi, Yoshihisa, Kawai-Yamada, Maki, Dupree, Paul, Tsumuraya, Yoichi, and Kotake, Toshihisa. Tue . "KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis". United States. doi:10.1105/tpc.15.00379.
@article{osti_1436989,
title = {KONJAC1 and 2 Are Key Factors for GDP-Mannose Generation and Affect l-Ascorbic Acid and Glucomannan Biosynthesis in Arabidopsis},
author = {Sawake, Shota and Tajima, Noriaki and Mortimer, Jenny C. and Lao, Jeemeng and Ishikawa, Toshiki and Yu, Xiaolan and Yamanashi, Yukiko and Yoshimi, Yoshihisa and Kawai-Yamada, Maki and Dupree, Paul and Tsumuraya, Yoichi and Kotake, Toshihisa},
abstractNote = {Humans are unable to synthesize L-ascorbic acid (AsA), yet it is required as a cofactor in many critical biochemical reactions. The majority of human dietary AsA is obtained from plants. In Arabidopsis thaliana, a GDP-mannose pyrophosphorylase (GMPP), VITAMIN C DEFECTIVE1 (VTC1), catalyzes a rate-limiting step in AsA synthesis: the formation of GDP-Man. In this study, we identified two nucleotide sugar pyrophosphorylase-like proteins, KONJAC1 (KJC1) and KJC2, which stimulate the activity of VTC1. The kjc1kjc2 double mutant exhibited severe dwarfism, indicating that KJC proteins are important for growth and development. The kjc1 mutation reduced GMPP activity to 10% of wild-type levels, leading to a 60% reduction in AsA levels. On the contrary, overexpression of KJC1 significantly increased GMPP activity. The kjc1 and kjc1kjc2 mutants also exhibited significantly reduced levels of glucomannan, which is also synthesized from GDP-Man. Recombinant KJC1 and KJC2 enhanced the GMPP activity of recombinant VTC1 in vitro, while KJCs did not show GMPP activity. Yeast two-hybrid assays suggested that the stimulation of GMPP activity occurs via interaction of KJCs with VTC1. These results suggest that KJCs are key factors for the generation of GDP-Man and affect AsA level and glucomannan accumulation through the stimulation of VTC1 GMPP activity.},
doi = {10.1105/tpc.15.00379},
journal = {Plant Cell},
issn = {1040-4651},
number = 12,
volume = 27,
place = {United States},
year = {2015},
month = {12}
}