Double-knockout of putative endo-β-N-acetylglucosaminidase (ENGase) genes in Arabidopsis thaliana: loss of ENGase activity induced accumulation of high-mannose type free N-glycans bearing N,N'-acetylchitobiosyl unit.

Endo-β-N-acetylglucosaminidase (ENGase) is involved in the production of high-mannose type free N-glycans during plant development and fruit maturation. In a previous study (K. Nakamura et al. Biosci. Biotechnol. Biochem., 73, 461-464 (2009)), we identified the tomato ENGase gene and found that gene expression remained relatively constant. In the present study, we constructed an Arabidopsis thaliana mutant in which the expression of two putative ENGase genes was suppressed. The mutant showed no ENGase activity, but produced high-mannose type free N-glycans carrying the N,N'-acetylchitobiosyl unit that is produced by peptide:N-glycanase, indicating that both these genes encode Arabidopsis ENGase.