Influence of N<Emphasis Type="Italic">-</Emphasis>Glycosylation on <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> Morphology: A Golgi Glycosylation Mutant Shows Cell Division Defects

The N-glycosylation mutants (mnn1 and mnn1 och1) show different morphological characteristics at the restrictive and nonpermissive temperature. We deleted the MNN1 to eliminate the terminal α1, 3-linked mannose of hypermannosylation and deleted the OCH1 to block the elongation of the main backbone chain. The mnn1 cells exhibited no observable change with respect to the wild-type strain at 28°C and 37°C, but the mnn1 och1 double mutant exhibited defects in cell cytokinesis, showed a slower growth rate, and became temperature-sensitive. Meanwhile, the mnn1 och1 mutant tended to aggregate, which was probably due to the glycolsylation defect. Loss of mannosyl-phosphate-accepting sites in this mutant migth result in reduced charge repulsion between cell surfaces. Pyridylaminated glycans were profiled and purified through an NH₂ column by size-fractionation high-performance liquid chromatography. Matrix assisted laser desoption/ionization time of flight mass spectrometry (MALDI TOF/MS) analysis of the N-glycan structure of the mnn1 och1 mutant revealed that the main component is Man₈GlcNAc₂.