Localization of type I myosin and F-actin to the leading edge region of the forespore membrane in Schizosaccharomyces pombe
Localization of type I myosin and F-actin to the leading edge region of the forespore membrane in Schizosaccharomyces pombe
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DOI：
10.1247/csf.06027
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发表时间：
2006-01-01
影响因子：
1.5
通讯作者：
Shimoda, Chikashi
中科院分区：
文献类型：
--
作者：
Itadani, Akiko;Nakamura, Taro;Shimoda, Chikashi
Myo 1是裂殖酵母裂殖酵母的I型肌球蛋白的重链，是孢子形成所必需的。在这里，我们已经分析了I型肌球蛋白轻链钙调蛋白，Cam 2，由cam 2（+）编码的表达，定位和细胞功能。cam 2（+）的转录是组成型的，在减数分裂中显著增强。cam 2无效突变体在28 ℃下正常存活并完成孢子形成，但在34 ℃下形成四孢子子囊较差。在这些孢子形成缺陷的细胞中，前孢子膜形成异常。Cam 2-GFP融合蛋白在间期细胞的细胞极和有丝分裂后细胞的内侧分隔部位积累，与Myo 1和F-actin斑块共定位。在交配过程中，在交配突起的尖端检测到单个Cam 2-GFP点。在减数分裂-I期间，Cam 2-GFP点分散到细胞周边和细胞质中。在中期II，强烈的Cam 2-GFP信号出现在Meu 14环附近，Meu 14环形成于扩展的前孢子膜的前缘。Cam 2的这种定位依赖于Myo 1，并且Cam 2 Delta在34 ℃下的孢子形成缺陷通过过表达Myo 1 Delta IQ而减轻。这些结果表明，Cam 2和Myo 1之间的密切关系。此外，F-actin和Myo 1都与Cam 2定位在前缘区域。总之，I型肌球蛋白和F-肌动蛋白积累在前孢子膜的前缘区域，并可能在其组装中发挥关键作用。
Myo1, a heavy chain of type I myosin of the fission yeast Schizosaccharomyces pombe, is essential for sporulation. Here we have analyzed the expression, localization and cellular function of the type I myosin light chain calmodulin, Cam2, encoded by cam2(+). Transcription of cam2(+) was constitutive and markedly enhanced in meiosis. The cam2 null mutant was viable and completed sporulation normally at 28 degrees C, but formed four-spored asci poorly at 34 degrees C. In those sporulation-defective cells, the forespore membrane was formed abnormally. A Cam2-GFP fusion protein accumulated at the cell poles in interphase cells and at the medial septation site in post-mitotic cells, colocalizing with Myo1 and F-actin patches. During the mating process, a single Cam2-GFP dot was detected at the tip of the mating projection. During meiosis-I, the Cam2-GFP dots dispersed into the cell periphery and the cytoplasm. At metaphase-II, intense Cam2-GFP signals appeared near Meu14 rings which were formed at the leading edge of expanding forespore membranes. This localization of Cam2 was dependent upon Myo1; and sporulation defect of cam2 Delta at 34 degrees C was alleviated by overexpressing Myo1 Delta IQ. These results suggest a close relationship between Cam2 and Myo1. In addition, both F-actin and Myo1 localized with Cam2 in the leading edge region. In summary, type I myosin and F-actin accumulate at the leading edge area of the forespore membrane and may play a pivotal role in its assembly.