Crystal Structures of Arabidopsis thaliana GDP-D-Mannose Pyrophosphorylase VITAMIN C DEFECTIVE 1

Chi Zhang; Shun Zhao; Yu-Shuai Li; Chao He; Xiao Wang; Lin Liu

doi:10.3389/fpls.2022.899738

Crystal Structures of Arabidopsis thaliana GDP-D-Mannose Pyrophosphorylase VITAMIN C DEFECTIVE 1

Front Plant Sci. 2022 May 23:13:899738. doi: 10.3389/fpls.2022.899738. eCollection 2022.

Authors

Chi Zhang¹, Shun Zhao², Yu-Shuai Li¹, Chao He^{1

3}, Xiao Wang^{1

3}, Lin Liu^{1

3}

Affiliations

¹ School of Life Sciences, Anhui University, Hefei, China.
² Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
³ Anhui Key Laboratory of Modern Biomanufacturing, Anhui University, Hefei, China.

Abstract

Plant GDP-D-mannose pyrophosphorylase (GMPase) catalyzes a committed step in ascorbic acid biosynthesis pathway. Arabidopsis thaliana VTC1 is the first genetically characterized plant GMPase and has unique properties when compared with bacterial and animal homologs. Here we present the crystal structures of VTC1 in the unliganded and product-bound states at resolutions of 2.8 and 3.0 Å, respectively. VTC1 dimerizes in a same way like other known GMPases, but dodecamerizes in a previously unobserved arrangement. The interactions to GDP-D-mannose and inorganic pyrophosphate are revealed by the product-bound VTC1 structure. An in vitro GMPase activity assay confirms the regulatory role of the C-terminal left-handed β-helix domain, and structural analyses suggest the models of VTC1 hetero-complex with its interacting proteins. The structural information advances our insights into the different mechanisms involved in VTC1 regulation.

Keywords: ascorbic acid; crystallography; guanylyltransferase; nucleotide sugar; oligomerization.