Hossain Tanim Jabid, Hirayama Hiroto, Harada Yoichiro, Suzuki Tadashi
a Glycometabolome Team, Systems Glycobiology Research Group , RIKEN-Max Planck Joint Research Center for Systems Chemical Biology, Global Research Cluster , Saitama , Japan.
b Graduate School of Science and Engineering , Saitama University , Saitama , Japan.
Biosci Biotechnol Biochem. 2016;80(1):152-7. doi: 10.1080/09168451.2015.1072464. Epub 2015 Aug 11.
In the cytosol of Saccharomyces cerevisiae, most of the free N-glycans (FNGs) are generated from misfolded glycoproteins by the action of the cytoplasmic peptide: N-glycanase (Png1). A cytosol/vacuole α-mannosidase, Ams1, then trims the FNGs to eventually form a trisaccharide composed of Manβ1,4GlcNAc β1,4GlcNAc (Man1GlcNAc2). Whether or not the resulting Man1GlcNAc2 is enzymatically degraded further, however, is currently unknown. The objective of this study was to unveil the fate of Man1GlcNAc2 in S. cerevisiae. Quantitative analyses of the FNGs revealed a steady increase in the amount of Man1GlcNAc2 produced in the post-diauxic and stationary phases, suggesting that this trisaccharide is not catabolized during this period. Inoculation of the stationary phase cells into fresh medium resulted in a reduction in the levels of Man1GlcNAc2. However, this reduction was caused by its dilution due to cell division in the fresh medium. Our results thus indicate that Man1GlcNAc2 is not enzymatically catabolized in S. cerevisiae.
在酿酒酵母的细胞质中，大多数游离N-聚糖（FNGs）是由细胞质肽：N-聚糖酶（Png1）作用于错误折叠的糖蛋白产生的。然后，一种细胞质/液泡α-甘露糖苷酶Ams1对FNGs进行修剪，最终形成由Manβ1,4GlcNAc β1,4GlcNAc（Man1GlcNAc2）组成的三糖。然而，目前尚不清楚由此产生的Man1GlcNAc2是否会被进一步酶解。本研究的目的是揭示酿酒酵母中Man1GlcNAc2的命运。对FNGs的定量分析表明，在二次生长后期和稳定期产生的Man1GlcNAc2量稳步增加，这表明这种三糖在此期间不会被分解代谢。将稳定期细胞接种到新鲜培养基中会导致Man1GlcNAc2水平降低。然而，这种降低是由于新鲜培养基中细胞分裂导致其稀释所致。因此，我们的结果表明，Man1GlcNAc2在酿酒酵母中不会被酶解。
