Phenotype of a Mechanosensitive Channel Mutant, mid-1, in a Filamentous Fungus, Neurospora crassa
Phenotype of a Mechanosensitive Channel Mutant, mid-1, in a Filamentous Fungus, Neurospora crassa
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DOI：
10.1128/ec.00411-07
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发表时间：
2008-02
期刊：
影响因子：
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通讯作者：
R. Lew;Zohaib Abbas;M. I. Anderca;S. Free
中科院分区：
文献类型：
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作者：
R. Lew;Zohaib Abbas;M. I. Anderca;S. Free
摘要 在酿酒酵母中，MID1（交配诱导死亡）基因编码成功交配所需的拉伸激活通道；突变表型可以通过细胞外钙的升高来挽救。 MID1 基因的同源物存在于与酵母相比形态复杂的真菌中，包括担子菌和子囊菌。我们探索了丝状子囊菌粗糙脉孢菌中 mid-1 敲除突变体的表型。突变体表现出比野生型（不能通过补充钙来挽救）更低的生长活力，并且可以成功交配。因此，MID-1 蛋白的作用不同于酵母中同源基因产物的作用。 mid-1突变体的菌丝细胞学、在不同碳源上的生长、膨压调节和昼夜节律都与野生型相似。然而，基础膨压低于野生型，质膜 H+-ATP 酶的活性也低于野生型（通过氰化物 [CN−] 诱导的膜电位能量依赖性成分的去极化来测量）。此外，该突变体无法在细胞外 Ca2+ 水平较低或 Ca2+ 离子载体 A23187 升高细胞质 Ca2+ 时生长。我们得出结论，MID-1 蛋白通过 Ca2+ 稳态和信号传导在离子转运调节中发挥作用。在缺乏正常离子转运活性的情况下，突变体表现出较差的生长。
ABSTRACT In the yeast Saccharomyces cerevisiae, the MID1 (mating-induced death) gene encodes a stretch-activated channel which is required for successful mating; the mutant phenotype is rescued by elevated extracellular calcium. Homologs of the MID1 gene are found in fungi that are morphologically complex compared to yeast, both Basidiomycetes and Ascomycetes. We explored the phenotype of a mid-1 knockout mutant in the filamentous ascomycete Neurospora crassa. The mutant exhibits lower growth vigor than the wild type (which is not rescued by replete calcium) and mates successfully. Thus, the role of the MID-1 protein differs from that of the homologous gene product in yeast. Hyphal cytology, growth on diverse carbon sources, turgor regulation, and circadian rhythms of the mid-1 mutant are all similar to those of the wild type. However, basal turgor is lower than wild type, as is the activity of the plasma membrane H+-ATPase (measured by cyanide [CN−]-induced depolarization of the energy-dependent component of the membrane potential). In addition, the mutant is unable to grow at low extracellular Ca2+ levels or when cytoplasmic Ca2+ is elevated with the Ca2+ ionophore A23187. We conclude that the MID-1 protein plays a role in regulation of ion transport via Ca2+ homeostasis and signaling. In the absence of normal ion transport activity, the mutant exhibits poorer growth.