Szabo R
Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia.
Mol Genet Genomics. 2001 Mar;265(1):172-9. doi: 10.1007/s004380000405.
The non-conventional yeast Yarrowia lipolytica is a suitable model for the study of yeast dimorphism. In order to identify genes that may be involved in the regulation of this process, random mutagenesis was performed. This led to the isolation of monomorphic mutants that had lost the ability to grow in a hyphal form both in liquid and on solid medium. Filamentation was restored to one of the mutants by transformation with a fragment of Y. lipolytica genomic DNA containing a single 2766-bp ORF. The predicted protein has a molecular weight of 99.6 kDa and is highly homologous to the protein kinases Cla4 of Candida albicans and Saccharomyces cerevisiae, which are members of the p21-activated kinase (PAK) family. Analysis of the putative protein sequence identified conserved C-terminal catalytic, and internal Cdc42p-binding regions, as well as a pleckstrin homology domain typical of PAK kinases. The results indicate that CLA4 is a single-copy gene located on the chromosome V of Y. lipolytica. Deletion of CLA4 is not lethal, but completely eliminates the ability to form filaments and to invade agar. A strain lacking a functional CLA4 gene exhibits an aberrant distribution of chitin in the cell wall, indicating a possible role for the Cla4 protein kinase in the maintenance of cell polarity in Y. lipolytica.
非常规酵母解脂耶氏酵母是研究酵母二态性的合适模型。为了鉴定可能参与该过程调控的基因，进行了随机诱变。这导致分离出单态突变体，这些突变体在液体和固体培养基中均丧失了以菌丝形式生长的能力。通过用包含单个2766 bp开放阅读框的解脂耶氏酵母基因组DNA片段进行转化，其中一个突变体恢复了丝状化。预测的蛋白质分子量为99.6 kDa，与白色念珠菌和酿酒酵母的蛋白激酶Cla4高度同源，它们是p21激活激酶（PAK）家族的成员。对推定的蛋白质序列分析确定了保守的C末端催化区域和内部Cdc42p结合区域，以及PAK激酶典型的普列克底物蛋白同源结构域。结果表明，CLA4是位于解脂耶氏酵母V号染色体上的单拷贝基因。CLA4的缺失并不致命，但完全消除了形成菌丝和侵入琼脂的能力。缺乏功能性CLA4基因的菌株在细胞壁中几丁质分布异常，表明Cla4蛋白激酶在解脂耶氏酵母细胞极性维持中可能发挥作用。
