Dissecting OGT's TPR domain to identify determinants of cellular function

• 成果类型: Article
• 署名作者: Potter, Sarah C.; Gibbs, Bettine E.; Hammel, Forrest A.; Joiner, Cassandra M.; Paulo, Joao A.; Janetzko, John; Levine, Zebulon G.; Fei, George Q.; Haggarty, Stephen J.; Walker, Suzanne
• 署名单位: Harvard University; Harvard Medical School; Harvard University; Harvard University Medical Affiliates; Massachusetts General Hospital; Harvard University; Harvard Medical School; Harvard University; Harvard Medical School; Harvard University; Saint Olaf College; Stanford University; Massachusetts Institute of Technology (MIT); Whitehead Institute
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-11373
• DOI: 10.1073/pnas.2401729121
• 发表日期: 2024-05-28
• 关键词: o-glcnac transferase; n-acetylglucosamine transferase; repeat domain; protein; cleavage; stress; ubiquitination; identification; proliferation; glycosylation

摘要

O - GlcNAc transferase (OGT) is an essential mammalian enzyme that glycosylates myriad intracellular proteins and cleaves the transcriptional coregulator Host Cell Factor 1 to regulate cell cycle processes. Via these catalytic activities as well as noncatalytic protein- protein interactions, OGT maintains cell homeostasis. OGT's tetratricopeptide repeat (TPR) domain is important in substrate recognition, but there is little information on how changing the TPR domain impacts its cellular functions. Here, we investigate how altering OGT's TPR domain impacts cell growth after the endogenous enzyme is deleted. We find that disrupting the TPR residues required for OGT dimerization leads to faster cell growth, whereas truncating the TPR domain slows cell growth. We also find that OGT requires eight of its 13 TPRs to sustain cell viability. OGT - 8, like the nonviable shorter OGT variants, is mislocalized and has reduced Ser/Thr glycosylation activity; moreover, its interactions with most of wild - type OGT's binding partners are broadly attenuated. Therefore, although OGT's five N - terminal TPRs are not essential for cell viability, they are required for proper subcellular localization and for mediating many of OGT's protein-protein interactions. Because the viable OGT truncation variant we have identified preserves OGT's essential functions, it may facilitate their identification.