Engase, also known as endo-β-N-acetylglucosaminidase (ENGASE/NAG), is a de-N-glycosylating enzyme. It acts on the innermost N-acetylglucosamine (GlcNAc) residue of the chitobiose segment of certain N-glycans, playing important roles in protein glyco-engineering, N-glycan metabolism, and protein quality control systems [1,3,5-7]. It may also be involved in pathways related to plant development, fruit ripening, and mammalian embryonic development [1,2]. Genetic models, like knockout mice, are valuable for studying its functions.

In mice, knockout of the Ngly1-gene leads to embryonic lethality, but this is partially rescued by the additional deletion of the Engase gene. This indicates that Engase might have a compensatory or interacting role with Ngly1 in mammalian development, and suggests that Ngly1/Engase-deficient mice could be a useful animal model for studying NGLY1-deficiency pathogenesis, with Engase being a potential therapeutic target for this genetic disorder [2]. In tomato plants, CRISPR-Cas9 mediated knockout of the Engase gene led to the loss of ENGase activity and changes in the structure of high-mannose-type free N-glycans, though no significant difference in fruit maturation was observed [3].

In conclusion, Engase is crucial for N-glycan-related processes in both plants and animals. Mouse knockout models have been instrumental in revealing its role in mammalian embryonic development and its potential as a therapeutic target for NGLY1-deficiency. In plants, knockout studies have provided insights into N-glycan-modifying mechanisms, despite no direct link to fruit maturation being found in the tomato model studied.

References:

1. Maeda, Megumi, Kimura, Yoshinobu. 2014. Structural features of free N-glycans occurring in plants and functional features of de-N-glycosylation enzymes, ENGase, and PNGase: the presence of unusual plant complex type N-glycans. In Frontiers in plant science, 5, 429. doi:10.3389/fpls.2014.00429. https://pubmed.ncbi.nlm.nih.gov/25237315/

2. Fujihira, Haruhiko, Masahara-Negishi, Yuki, Tamura, Masaru, Funakoshi, Yoko, Suzuki, Tadashi. 2017. Lethality of mice bearing a knockout of the Ngly1-gene is partially rescued by the additional deletion of the Engase gene. In PLoS genetics, 13, e1006696. doi:10.1371/journal.pgen.1006696. https://pubmed.ncbi.nlm.nih.gov/28426790/

3. Okamoto, Naoko, Maeda, Megumi, Yamamoto, Chiharu, Ezura, Hiroshi, Kimura, Yoshinobu. 2022. Construction of tomato plants with suppressed endo-β-N-acetylglucosaminidase activity using CRISPR-Cas9 mediated genome editing. In Plant physiology and biochemistry : PPB, 190, 203-211. doi:10.1016/j.plaphy.2022.08.009. https://pubmed.ncbi.nlm.nih.gov/36130423/