Protein O‐GlcNAcylation impairment caused by N‐acetylglucosamine phosphate mutase deficiency leads to growth variations in Arabidopsis thaliana

Abstract

SUMMARYAs an essential enzyme in the uridine diphosphate (UDP)‐GlcNAc biosynthesis pathway, the significant role of N‐acetylglucosamine phosphate mutase (AGM) remains unknown in plants. In the present study, a functional plant AGM (AtAGM) was identified from Arabidopsis thaliana. AtAGM catalyzes the isomerization of GlcNAc‐1‐P and GlcNAc‐6‐P, and has broad catalytic activity on different phosphohexoses. UDP‐GlcNAc contents were significantly decreased in AtAGM T‐DNA insertional mutants, which caused temperature‐dependent growth defects in seedlings and vigorous growth in adult plants. Further analysis revealed that protein O‐GlcNAcylation but not N‐glycosylation was dramatically impaired in Atagm mutants due to UDP‐GlcNAc shortage. Combined with the results from O‐GlcNAcylation or N‐glycosylation deficient mutants, and O‐GlcNAcase inhibitor all suggested that protein O‐GlcNAcylation impairment mainly leads to the phenotypic variations of Atagm plants. In conclusion, based on the essential role in UDP‐GlcNAc biosynthesis, AtAGM is important for plant growth mainly via protein O‐GlcNAcylation‐level regulation.