The Metabolic Chemical Reporter Ac46AzGal Could Incorporate Intracellular Protein Modification in the Form of UDP-6AzGlc Mediated by OGT and Enzymes in the Leloir Pathway

Jiajia Wang; Biao Dou; Lu Zheng; Wei Cao; Peiyu Dong; Yingyi Chen; Xueke Zeng; Yinhang Wen; Wenxuan Pan; Jing Ma; Jingying Chen; Xia Li

doi:10.3389/fchem.2021.708306

The Metabolic Chemical Reporter Ac₄6AzGal Could Incorporate Intracellular Protein Modification in the Form of UDP-6AzGlc Mediated by OGT and Enzymes in the Leloir Pathway

Front Chem. 2021 Oct 12:9:708306. doi: 10.3389/fchem.2021.708306. eCollection 2021.

Authors

Jiajia Wang^{1

2}, Biao Dou¹, Lu Zheng¹, Wei Cao¹, Peiyu Dong¹, Yingyi Chen¹, Xueke Zeng¹, Yinhang Wen¹, Wenxuan Pan³, Jing Ma³, Jingying Chen¹, Xia Li¹

Affiliations

¹ Joint National Laboratory for Antibody Drug Engineering, the First Affiliated Hospital of Henan University, School of Basic Medicine Science, Henan University, Kaifeng, China.
² State Key Laboratory of Medicinal Chemical Biology, Haihe Education Park, Nankai University, Tianjin, China.
³ School of Pharmacy, Institute for Innovative Drug Design and Evaluation, Henan University, Kaifeng, China.

Abstract

Galactose is a naturally occurring monosaccharide used to build complex glycans that has not been targeted for labeling as a metabolic reporter. Here, we characterize the cellular modification of proteins by using Ac₄6AzGal in a dose- and time-dependent manner. It is noted that a vast majority of this labeling of Ac₄6AzGal occurs intracellularly in a range of mammalian cells. We also provided evidence that this labeling is dependent on not only the enzymes of OGT responsible for O-GlcNAcylation but also the enzymes of GALT and GALE in the Leloir pathway. Notably, we discover that Ac₄6AzGal is not the direct substrate of OGT, and the labeling results may attribute to UDP-6AzGlc after epimerization of UDP-6AzGal via GALE. Together, these discoveries support the conclusion that Ac₄6AzGal as an analogue of galactose could metabolically label intracellular O-glycosylation modification, raising the possibility of characterization with impaired functions of the galactose metabolism in the Leloir pathway under certain conditions, such as galactosemias.

Keywords: Ac46AzGalactose; GALE; GALT; Leloir pathway; OGT/OGA; metabolic chemical reporter.