earticle

영어

Mannosylphosphorylated glycans, which confers negative charges on the cell surface, are only found in yeasts and fungi groups. Both MNN4 and MNN6 genes are required for mannosylphosphorylation in the traditional yeast Saccharomyces cerevisiae. Mnn4 protein has been known to be a positive regulator of Mnn6p, a real enzyme for mannosylphosphorylation. We constructed the quadruple-disrupted och1Δmnn1 Δmnn4Δmnn6Δ strain by disrupting MNN4 and MNN6 genes from the och1Δmnn1Δ strain in which yeast-specific hyper-mannosylated glycan and immunogenic α(1,3)-mannose structures were already abolished [1]. However, yeast-specific mannosylphosphorylated N-glycan structures were still observed in the och1Δmnn1Δmnn4Δmnn6Δ strain, which suggests that there is another gene involved in mannosylphosphorylation. From the och1Δmnn1Δmnn4Δmnn6Δ strain, we further disrupted the genes (MNN14, YUR1, KTR2, KTR4, KTR5, or KTR7) having homology with MNN4 or MNN6 genes. Analyses of N-glycans obtained from cell wall mannoproteins of six quintuple-disrupted strains indicated that mannosylphosphorylated glycan structure was completely abolished only in the och1Δmnn1Δmnn4Δ mnn6Δmnn14Δ strain. Since MNN14 has the homology with MNN4, the och1Δmnn1Δmnn14Δ and och1 Δmnn1Δmnn4Δmnn14Δ strains were constructed. While mannosylphoshorylated N-glycans were observed in och1Δmnn1Δmnn14Δ strain, there was no mannosylphosphorylation in the och1Δmnn1Δmnn4Δmnn14Δ strain, which clearly shows that disruption of both MNN4 and MNN14 genes was required to remove mannosylphosphorylated glycan structures. Complementation of one gene (either MNN4 or MNN14) restored mannosylphosphorylation in the och1Δmnn1Δmnn4Δmnn14Δ strain, which supports that MNN4 and MNN14 can play a redundant role on the deficiency of one gene. The och1Δmnn1Δmnn4Δmnn14Δ strain without any yeast-specific glycan structure will serve as an useful platform for production of glycoproteins with human-compatible N-glycans.