Natural synchronisation for the study of cell division in the green unicellular alga Ostreococcus tauri
Natural synchronisation for the study of cell division in the green unicellular alga Ostreococcus tauri
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DOI：
10.1007/s11103-005-4066-1
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发表时间：
2006-01-01
影响因子：
5.1
通讯作者：
Moreau, H
中科院分区：
文献类型：
--
作者：
Farinas, B;Mary, C;Moreau, H
Tauri（Prasinophyceae）是一种海洋单细胞绿色球藻，在绿色谱系早期就分化了。O. Tauri作为研究植物细胞分裂的潜在模型是基于其关键的系统发育位置、其简单的二进制分裂、非常简单的细胞组织以及现在全基因组序列的可用性。此外，O.金牛座有一套最小但完整的细胞周期控制基因。在这里，我们表明，分裂可以自然同步的光/暗周期和细胞器分裂细胞核之前。这种自然的同步，虽然只是部分的，使整个细胞周期的CDK的表达的研究。在mRNA和蛋白水平上测定OtCDKA和OtCDKB的表达模式。单个OtCDKA基因在整个细胞周期中持续表达，而OtCDKB仅在S/G2/M期高度调节和表达。更令人惊讶的是，与在细胞分裂期间强烈磷酸化的OtCDKB相反，OtCDKA在酪氨酸残基处不磷酸化。OtCDKA激酶活性出现在S期之前，表明该蛋白在G1/S转换中可能起作用。OtCDKB激酶活性发生晚于OtCDKA，其酪氨酸磷酸化与G2/M相关，表明可能控制有丝分裂活性。据我们所知，这是绿色谱系中第一个在细胞周期进程中显示CDKB酪氨酸磷酸化的生物体。
Ostreococcus tauri (Prasinophyceae) is a marine unicellular green alga which diverged early in the green lineage. The interest of O. tauri as a potential model to study plant cell division is based on its key phylogenetic position, its simple binary division, a very simple cellular organisation and now the availability of the full genome sequence. In addition O. tauri has a minimal yet complete set of cell cycle control genes. Here we show that division can be naturally synchronised by light/dark cycles and that organelles divide before the nucleus. This natural synchronisation, although being only partial, enables the study of the expression of CDKs throughout the cell cycle. The expression patterns of OtCDKA and OtCDKB were determined both at the mRNA and protein levels. The single OtCDKA gene is constantly expressed throughout the cell cycle, whereas OtCDKB is highly regulated and expressed only in S/G2/M phases. More surprisingly, OtCDKA is not phosphorylated at the tyrosine residue, in contrast to OtCDKB which is strongly phosphorylated during cell division. OtCDKA kinase activity appears before the S phase, indicating a possible role of this protein in the G1/S transition. OtCDKB kinase activity occurs later than OtCDKA, and its tyrosine phosphorylation is correlated to G2/M, suggesting a possible control of the mitotic activity. To our knowledge this is the first organism in the green lineage which showed CDKB tyrosine phosphorylation during cell cycle progression.