The formation of actin rods composed of actin tubules in Dictyostelium discoideum spores.
The formation of actin rods composed of actin tubules in Dictyostelium discoideum spores.
复制标题
盘基网柄菌孢子中由肌动蛋白小管组成的肌动蛋白棒的形成。
DOI：
10.1006/jsbi.2001.4424
复制
发表时间：
2001
影响因子：
3
通讯作者：
D. Cotter
中科院分区：
文献类型：
--
作者：
M. Sameshima;Y. Kishi;M. Osumi;R. Minamikawa;D. Mahadeo;D. Cotter
在胞核和胞浆中形成的一种新型肌动蛋白棒，以及肌动蛋白的酪氨酸磷酸化，与盘状网柄菌孢子休眠的维持和活力有关。在这里，我们观察了肌动蛋白的超微结构及其与肌动蛋白磷酸化的关系。杆状物最早出现在未成熟的孢子中，出现在顶峰中期，是由六角形交叉的肌动蛋白小管组成的束。直径13 nm的肌动蛋白束由3根肌动蛋白细丝组成。肌动蛋白棒的形成始于末梢阶段，一直持续到子实体完成后2天。物理事件按下列顺序发生：几个束模块的结合、紧密堆积和肌动蛋白小管直径减小、杆状延伸穿过细胞核或细胞质。肌动蛋白的磷酸化水平在顶峰后期升高，12h后达到最高水平。在孢子萌发被激活后，肌动蛋白立即被迅速去磷酸化，随后不久杆状突起消失。缩短的肌动蛋白小管再次呈六角形排列。肌动蛋白小管的这种六角形排列可能参与了视杆的形成和消失，并不依赖于肌动蛋白的磷酸化。相反，杆状成熟过程可能与肌动蛋白的磷酸化有关。
A new type of actin rod formed in both the nucleus and the cytoplasm, as well as tyrosine phosphorylation of actin, is implicated in the maintenance of dormancy and viability of Dictyostelium discoideum spores. Here the ultrastructure of the rods and their relationship to the phosphorylation of actin were examined. The rods first appeared in premature spores at the midculmination stage as bundles composed of actin tubules hexagonally cross-linked. The 13-nm-diameter bundles were composed of three actin filaments. Formation of the actin rods begins during the late culmination stage and proceeds until 2 days after completion of fruiting bodies. The physical events occur in the following order; association of several modules of bundles, close packing and decrease in diameter of actin tubules, elongation of rods across the nucleus or the cytoplasm. Actin phosphorylation levels increased at the late culmination stage and reached a maximum level 12 h later. Immediately following activation of spore germination, actin was rapidly dephosphorylated, followed shortly thereafter by the disappearance of rods. Shortened actin tubules once again became arranged in a hexagonal pattern. This hexagonal arrangement of actin tubules is possibly involved in rod formation and disappearance and does not depend upon actin phosphorylation. In contrast, rod-maturation processes may correlate with actin phosphorylation.