1. Academic Validation
  2. O-GlcNAcylation of Thr12/Ser56 in short-form O-GlcNAc transferase (sOGT) regulates its substrate selectivity

O-GlcNAcylation of Thr12/Ser56 in short-form O-GlcNAc transferase (sOGT) regulates its substrate selectivity

  • J Biol Chem. 2019 Nov 8;294(45):16620-16633. doi: 10.1074/jbc.RA119.009085.
Li Liu 1 Ling Li 1 Cheng Ma 2 Yangde Shi 1 Congcong Liu 1 Zikang Xiao 1 Yong Zhang 3 4 Fang Tian 3 Yang Gao 5 Jie Zhang 5 Wantao Ying 6 Peng George Wang 1 2 Lianwen Zhang 7
Affiliations

Affiliations

  • 1 College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300353, China.
  • 2 Center for Diagnostics and Therapeutics, Department of Chemistry, Georgia State University, Atlanta, Georgia 30303.
  • 3 State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 102206, China.
  • 4 West China-Washington Mitochondria and Metabolism Research Center, Key Laboratory of Transplant Engineering and Immunology, MOH, West China Hospital, Sichuan University, Chengdu 610041, China.
  • 5 School of medicine, Nankai University, Tianjin 300071, China.
  • 6 State Key Laboratory of Proteomics, Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 102206, China yingwantao@mail.ncpsb.org.cn.
  • 7 College of Pharmacy and Tianjin Key Laboratory of Molecular Drug Research, Nankai University, Tianjin 300353, China lianwen@nankai.edu.cn.
Abstract

O-GlcNAcylation is a ubiquitous protein glycosylation playing different roles on variant proteins. O-GlcNAc transferase (OGT) is the unique Enzyme responsible for the sugar addition to nucleocytoplasmic proteins. Recently, multiple O-GlcNAc sites have been observed on short-form OGT (sOGT) and nucleocytoplasmic OGT (ncOGT), both of which locate in the nucleus and cytoplasm in cell. Moreover, O-GlcNAcylation of Ser389 in ncOGT (1036 Amino acids) affects its nuclear translocation in HeLa cells. To date, the major O-GlcNAcylation sites and their roles in sOGT remain unknown. Here, we performed LC-MS/MS and mutational analyses to seek the major O-GlcNAcylation site on sOGT. We identified six O-GlcNAc sites in the tetratricopeptide repeat domain in sOGT, with Thr12 and Ser56 being two "key" sites. Thr12 is a dominant O-GlcNAcylation site, whereas the modification of Ser56 plays a role in regulating sOGT O-GlcNAcylation, partly through Thr12In vitro activity and pulldown assays demonstrated that O-GlcNAcylation does not affect sOGT activity but does affect sOGT-interacting proteins. In HEK293T cells, S56A bound to and hence glycosylated more proteins in contrast to T12A and WT sOGT. By proteomic and bioinformatics analyses, we found that T12A and S56A differed in substrate proteins (e.g. HNRNPU and PDCD6IP), which eventually affected cell cycle progression and/or cell proliferation. These findings demonstrate that O-GlcNAcylation modulates sOGT substrate selectivity and affects its role in the cell. The data also highlight the regulatory role of O-GlcNAcylation at Thr12 and Ser56.

Keywords

G2/M arrest; O-GlcNAcylation; O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT); cell cycle; cell proliferation; enzyme kinetics; sOGT; substrate selectivity.

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