Zhang Bowen, Teraguchi Erika, Imada Kazuki, Tahara Yuhei O, Nakamura Shuko, Miyata Makoto, Kagiwada Satoshi, Nakamura Taro
Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka 558-8585, Japan.
Department of Chemistry and Biochemistry, National Institute of Technology, Suzuka College, Suzuka 510-0294, Japan.
J Fungi (Basel). 2020 Nov 13;6(4):284. doi: 10.3390/jof6040284.
In , the spore wall confers strong resistance against external stress. During meiosis II, the double-layered intracellular forespore membrane (FSM) forms de novo and encapsulates the nucleus. Eventually, the inner FSM layer becomes the plasma membrane of the spore, while the outer layer breaks down. However, the molecular mechanism and biological significance of this membrane breakdown remain unknown. Here, by genetic investigation of an mutant (E22) with normal prespore formation but abnormal spores, we showed that Meu5, an RNA-binding protein known to bind to and stabilize more than 80 transcripts, is involved in this process. We confirmed that the E22 mutant does not produce Meu5 protein, while overexpression of in E22 restores the sporulation defect. Furthermore, electron microscopy revealed that the outer membrane of the FSM persisted in ∆ spores. Investigation of the target genes of showed that a mutant of encoding cytochrome also showed a severe defect in outer FSM breakdown. Lastly, we determined that outer FSM breakdown occurs coincident with or after formation of the outermost Isp3 layer of the spore wall. Collectively, our data provide novel insights into the molecular mechanism of spore formation.
在[具体情况未提及]中，孢子壁赋予了对外部压力的强大抵抗力。在减数分裂II期间，双层细胞内前孢子膜（FSM）重新形成并包裹细胞核。最终，FSM的内层成为孢子的质膜，而外层则分解。然而，这种膜分解的分子机制和生物学意义仍然未知。在这里，通过对一个前孢子形成正常但孢子异常的突变体（E22）进行基因研究，我们表明Meu5，一种已知能结合并稳定80多种转录本的RNA结合蛋白，参与了这一过程。我们证实E22突变体不产生Meu5蛋白，而在E22中过表达[具体基因未提及]可恢复孢子形成缺陷。此外，电子显微镜显示FSM的外膜在∆孢子中持续存在。对[具体基因未提及]的靶基因研究表明，编码细胞色素的[具体基因未提及]突变体在FSM外膜分解方面也存在严重缺陷。最后，我们确定FSM外膜分解与孢子壁最外层Isp3层的形成同时发生或在其之后发生。总的来说，我们的数据为孢子形成的分子机制提供了新的见解。
