Uccelletti Daniela, Farina Francesca, Rufini Silvia, Magnelli Paula, Abeijon Claudia, Palleschi Claudio
Department of Developmental and Cell Biology, University La Sapienza, Rome, Italy.
FEMS Yeast Res. 2006 May;6(3):449-57. doi: 10.1111/j.1567-1364.2006.00027.x.
Mutants of Kluyveromyces lactis denominated vga (vanadate glycosylation affected) bear various combinations of glycosylation and cell-wall defects. The vga3 mutation of K. lactis was mapped in the KlOCH1 gene, encoding the functional homologue of the Saccharomyces cerevisiaealpha1,6-mannosyltransferase. Quantitative analysis of cell-wall components indicated a noticeable increase of chitin and beta1,6-glucans and a severe decrease of mannoproteins in the mutant cells as compared with the wild-type counterparts. Fine-structure determination of the beta1,6-glucan polymer indicated that, in the vga3-1 strain, the beta1,6-glucans are shorter and have more branches than in the wild-type strain. This suggests that cell-wall remodelling changes take place in K. lactis in the presence of glycosylation defects. Moreover, the vga3 cells showed a significantly improved capability of secreting heterologous proteins. Such a capability, accompanied by the highly reduced N-glycosylation, may be of biotechnological interest, especially when hyper-glycosylation of recombinant products must be avoided.
命名为vga（钒酸盐糖基化受影响）的乳酸克鲁维酵母突变体具有各种糖基化和细胞壁缺陷的组合。乳酸克鲁维酵母的vga3突变定位在KlOCH1基因中，该基因编码酿酒酵母α1,6-甘露糖基转移酶的功能同源物。细胞壁成分的定量分析表明，与野生型细胞相比，突变体细胞中的几丁质和β1,6-葡聚糖显著增加，而甘露糖蛋白严重减少。β1,6-葡聚糖聚合物的精细结构测定表明，在vga3-1菌株中，β1,6-葡聚糖比野生型菌株中的更短且分支更多。这表明在存在糖基化缺陷的情况下，乳酸克鲁维酵母中发生了细胞壁重塑变化。此外，vga3细胞分泌异源蛋白的能力显著提高。这种能力伴随着高度降低的N-糖基化，可能具有生物技术意义，特别是当必须避免重组产物的过度糖基化时。
