Kapteyn J C, Van Egmond P, Sievi E, Van Den Ende H, Makarow M, Klis F M
Center for Fungal Cell Wall Research, University of Amsterdam, The Netherlands.
Mol Microbiol. 1999 Mar;31(6):1835-44. doi: 10.1046/j.1365-2958.1999.01320.x.
The cell wall of yeast contains a major structural unit, consisting of a cell wall protein (CWP) attached via a glycosylphosphatidylinositol (GPI)-derived structure to beta 1,6-glucan, which is linked in turn to beta 1, 3-glucan. When isolated cells walls were digested with beta 1,6-glucanase, 16% of all CWPs remained insoluble, suggesting an alternative linkage between CWPs and structural cell wall components that does not involve beta 1,6-glucan. The beta 1,6-glucanase-resistant protein fraction contained the recently identified GPI-lacking, O-glycosylated Pir-CWPs, including Pir2p/Hsp150. Evidence is presented that Pir2p/Hsp150 is attached to beta 1,3-glucan through an alkali-sensitive linkage, without beta 1,6-glucan as an interconnecting moiety. In beta 1,6-glucan-deficient mutants, the beta 1,6-glucanase-resistant protein fraction increased from 16% to over 80%. This was accompanied by increased incorporation of Pir2p/Hsp150. It is argued that this is part of a more general compensatory mechanism in response to cell wall weakening caused by low levels of beta 1,6-glucan.
酵母细胞壁含有一个主要结构单元，它由一种细胞壁蛋白（CWP）组成，该蛋白通过糖基磷脂酰肌醇（GPI）衍生结构与β-1,6-葡聚糖相连，而β-1,6-葡聚糖又与β-1,3-葡聚糖相连。当用β-1,6-葡聚糖酶消化分离的细胞壁时，所有CWP中有16%仍不溶，这表明CWP与细胞壁结构成分之间存在一种不涉及β-1,6-葡聚糖的替代连接。β-1,6-葡聚糖酶抗性蛋白组分包含最近鉴定出的缺乏GPI、O-糖基化的Pir-CWP，包括Pir2p/Hsp150。有证据表明，Pir2p/Hsp150通过一种对碱敏感的连接与β-1,3-葡聚糖相连，而没有β-1,6-葡聚糖作为连接部分。在β-1,6-葡聚糖缺陷型突变体中，β-1,6-葡聚糖酶抗性蛋白组分从16%增加到80%以上。这伴随着Pir2p/Hsp150掺入量的增加。有人认为，这是对低水平β-1,6-葡聚糖导致的细胞壁弱化的一种更普遍的补偿机制的一部分。
