Yeast yapsins and cell wall assembly

我们的实验室感兴趣的是一个独特的真菌酶家族，统称为‘yapsins’，在酵母细胞壁的组装中的调节和功能作用。这种结构非常复杂，对所有真菌的生存都是必不可少的，包括人类机会主义病原体，如白色念珠菌。这个家族的第一个成员是Yps1酶，我们和其他人十年前在酿酒酵母中发现了这种酶。我们现在知道这些酶中有五个成员在酿酒酵母中表达，它们都定位在细胞表面。最近的研究表明，这些酶与细胞壁组装的某些方面有关，但直到最近，还没有发现这些酶的底物。我们最近在酿酒酵母中鉴定了一些Yps1的天然底物，这些底物的性质清楚地证实了Yps1参与了细胞壁的组装。我们最近的研究还表明：1)在它们在细胞内运输到达细胞表面的过程中，这些酶与大多数其他注定要分泌的蛋白质保持分离；2)环境pH调节这种酶的活性。在目前的提案中，我们设计了实验以：1)确定额外的Yps1底物；2)确认和了解这种酶所进行的特定细胞内转运的意义；以及3)了解是什么控制了这种酶的活性。除了加深我们对真菌Yapsins如何调节酵母细胞壁组装的理解外，拟议的研究还将有助于设计特定的抑制剂，从而可能导致新的抗真菌药物的开发。

Our laboratory is interested in the regulation and functional role of a unique family of fungal enzymes, collectively known as 'yapsins', in the assembly of the yeast cell wall. This structure is highly complex and essential for the viability of all fungi, including human opportunist pathogens such as C. albicans. The first member of this family is the Yps1 enzyme that we, and others, identified in the brewer yeast S. cerevisiae a decade ago. We now know that five members of theses enzymes are expressed in S. cerevisiae, all of them are localized at the cell surface. Recent studies suggested that these enzymes were implicated in some aspects of cell wall assembly, but until recently, no substrate for any of these enzymes had been identified. We recently identified some natural substrates for Yps1 in S. cerevisiae and the nature of these substrates clearly confirmed that Yps1 participate in the cell wall assembly. Our recent study also suggested that: 1) during their intracellular transport to reach the cell surface, these enzymes are kept apart from most other proteins destined for secretion; and 2) the environmental pH regulates the activity of this enzyme. In the current proposal we have designed experiments to: 1) identify additional Yps1 substrates; 2) confirm and understand the significance of the particular intracellular transport that this enzyme is taking; and 3) understand what controls the activity of this enzyme. In addition to deepen our understanding on how fungal yapsins regulate cell wall assembly in yeast, the proposed studies should help designing specific inhibitors that may lead to the development of novel antifungal agents.