Smits Gertien J, Schenkman Laura R, Brul Stanley, Pringle John R, Klis Frans M
Swammerdam Institute for Life Sciences, BioCentrum Amsterdam, University of Amsterdam, 1018 WV Amsterdam, The Netherlands.
Mol Biol Cell. 2006 Jul;17(7):3267-80. doi: 10.1091/mbc.e05-08-0738. Epub 2006 May 3.
The yeast cell wall is an essential organelle that protects the cell from mechanical damage and antimicrobial peptides, participates in cell recognition and adhesion, and is important for the generation and maintenance of normal cell shape. We studied the localization of three covalently bound cell wall proteins in Saccharomyces cerevisiae. Tip1p was found only in mother cells, whereas Cwp2p was incorporated in small-to-medium-sized buds. When the promoter regions of TIP1 and CWP2 (responsible for transcription in early G1 and S/G2 phases, respectively) were exchanged, the localization patterns of Tip1p and Cwp2p were reversed, indicating that the localization of cell wall proteins can be completely determined by the timing of transcription during the cell cycle. The third protein, Cwp1p, was incorporated into the birth scar, where it remained for several generations. However, we could not detect any role of Cwp1p in strengthening the birth scar wall or any functional interaction with the proteins that mark the birth scar pole as a potential future budding site. Promoter-exchange experiments showed that expression in S/G2 phase is necessary but not sufficient for the normal localization of Cwp1p. Studies of mutants in which septum formation is perturbed indicate that the normal asymmetric localization of Cwp1p also depends on the normal timing of septum formation, composition of the septum, or both.
酵母细胞壁是一种重要的细胞器，可保护细胞免受机械损伤和抗菌肽的侵害，参与细胞识别和黏附，对于正常细胞形态的形成和维持也很重要。我们研究了酿酒酵母中三种共价结合的细胞壁蛋白的定位。Tip1p仅在母细胞中发现，而Cwp2p则整合到中小型芽中。当TIP1和CWP2的启动子区域（分别负责G1早期和S/G2期的转录）交换时，Tip1p和Cwp2p的定位模式发生了逆转，这表明细胞壁蛋白的定位可以完全由细胞周期中的转录时间决定。第三种蛋白Cwp1p整合到出芽痕中，并在那里保留几代。然而，我们未检测到Cwp1p在加强出芽痕壁方面的任何作用，也未发现它与标记出芽痕极作为潜在未来出芽位点的蛋白质之间存在任何功能相互作用。启动子交换实验表明，S/G2期的表达对于Cwp1p的正常定位是必要的，但并不充分。对隔膜形成受到干扰的突变体的研究表明，Cwp1p的正常不对称定位也取决于隔膜形成的正常时间或隔膜的组成，或两者皆有。
