Key Laboratory of Molecular and Developmental Biology, National Centre for Plant Gene Research, Institute of Genetics and Developmental Biology, the Chinese Academy of Sciences, Beijing, China.
J Integr Plant Biol. 2010 Sep;52(9):817-28. doi: 10.1111/j.1744-7909.2010.00972.x.
RNA helicases are adenosine tri-phosphatases that unwind the secondary structures of RNAs and are required in almost any aspect of RNA metabolism. They are highly conserved from prokaryotic to eukaryotic organisms. However, their precise roles in plant physiology and development remain to be clarified. Here we report that the mutation in the gene SLOW WALKER3 (SWA3) results in the slow and retarded progression of mitosis during megagametogenesis in Arabidopsis. SWA3 is a putative RNA helicase of the DEAD-box subfamily. Mutant megagametophyte development is arrested at four- or eight-nucleate stages, furthermore, one of the synergids in about half of the mutant embryo sacs displays abnormal polarity, with its nucleus locating at the chalazal end, instead of the micropylar end in the wild-type. Transmission of the mutation through female gametophytes is severely reduced in swa3. However, a small portion of mutant embryo sacs are able to develop into mature and functional female gametophytes when pollination was postponed. The SWA3 in Arabidopsis is a homolog of Dbp8 in yeast. Dbp8 interacts with Efs2 and is essential for biogenesis of 18S rRNA in yeast. Our data suggest that SWA3 may form a complex with AtEfs2 and take roles in ribosomal biogenesis as RNA helicase during megagametogenesis in Arabidopsis.
RNA 解旋酶是三磷酸腺苷酶，可解开 RNA 的二级结构，几乎在 RNA 代谢的任何方面都需要它们。它们在原核生物到真核生物中高度保守。然而，它们在植物生理学和发育中的精确作用仍有待阐明。在这里，我们报道 SLOW WALKER3（SWA3）基因突变导致拟南芥大配子发生过程中有丝分裂的缓慢和迟滞进展。SWA3 是 DEAD-box 亚家族的一种假定 RNA 解旋酶。突变体大配子体发育在四核或八核阶段停滞，此外，在大约一半的突变胚囊中，一个助细胞显示出异常的极性，其细胞核位于合点端，而不是在野生型中的珠孔端。在 swa3 中，通过雌性配子体的突变传递严重减少。然而，当授粉推迟时，一小部分突变胚囊能够发育成成熟和功能的雌性配子体。拟南芥中的 SWA3 是酵母中 Dbp8 的同源物。Dbp8 与 Efs2 相互作用，对于酵母中 18S rRNA 的生物发生是必需的。我们的数据表明，SWA3 可能与 AtEfs2 形成复合物，并作为 RNA 解旋酶在拟南芥大配子发生过程中参与核糖体生物发生。
