Böer Erik, Wartmann Thomas, Dlubatz Karen, Gellissen Gerd, Kunze Gotthard
Institut für Pflanzengenetik und Kulturpflanzenforschung, Corrensstrasse 3, 06466 Gatersleben, Germany.
Curr Genet. 2004 Nov;46(5):269-76. doi: 10.1007/s00294-004-0535-3.
Arxula adeninivorans is an osmo-resistant yeast species that can tolerate high levels of osmolytes like NaCl, PEG400 and ethylene glycol. As in other yeast species, this tolerance is elicited by components of the high osmolarity glycerol (HOG) response pathway. In the present study, we isolated and characterized as a key component of this pathway the A. adeninivorans AHOG1 gene encoding the mitogen-activated protein (MAP) kinase Ahog1p, an enzyme of 45.9 kDa. The gene includes a coding sequence of 1,203 bp disrupted by a 57-bp intron. The identity of the gene was confirmed by complementation of a hog1 mutation in a Saccharomyces cerevisiae mutant strain and the high degree of homology of the derived amino acid sequence with that of MAP kinases from other yeasts and fungi. Under stress-free conditions, the inactive Ahoglp is present in low levels. When exposed to osmotic stress, Ahoglp is rendered active by phosphorylation. In addition, AHOG1 expression is increased. Assessment of the AHOG1 promoter activity with a lacZ reporter gene confirmed its inducibility by osmolytes, a characteristic not observed in homologous HOG1 genes of other yeast species. This specific property could account for the fast adaptation and high osmo-resistance encountered in this species.
嗜腺嘌呤阿氏酵母是一种耐渗透压的酵母物种，能够耐受高浓度的渗透压剂，如氯化钠、聚乙二醇400和乙二醇。与其他酵母物种一样，这种耐受性是由高渗甘油（HOG）应答途径的组分引发的。在本研究中，我们分离并鉴定了嗜腺嘌呤阿氏酵母AHOG1基因，它编码丝裂原活化蛋白（MAP）激酶Ahog1p，该酶分子量为45.9 kDa，是该途径的关键组分。该基因包含一个1203 bp的编码序列，被一个57 bp的内含子打断。通过对酿酒酵母突变株中hog1突变的互补以及推导的氨基酸序列与其他酵母和真菌的MAP激酶的高度同源性，证实了该基因的身份。在无应激条件下，无活性的Ahoglp水平较低。当暴露于渗透胁迫时，Ahoglp通过磷酸化而被激活。此外，AHOG1的表达增加。用lacZ报告基因评估AHOG1启动子活性证实了它可被渗透压剂诱导，这一特性在其他酵母物种的同源HOG1基因中未观察到。这种特殊性质可以解释该物种所具有的快速适应和高耐渗透压能力。
