State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, China.
Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Science, South China Normal University, Guangzhou 510631, China.
Plant Cell. 2020 Apr;32(4):1270-1284. doi: 10.1105/tpc.19.00791. Epub 2020 Feb 21.
Male and female gametophytes are generated from micro- or megaspore mother cells through consecutive meiotic and mitotic cell divisions. Defects in these divisions often result in gametophytic lethality. Gametophytic lethality was also reported when genes encoding ribosome-related proteins were mutated. Although numerous ribosomal proteins (RPs) have been identified in plants based on homology with their yeast and metazoan counterparts, how RPs are regulated, e.g., through dynamic subcellular targeting, is unknown. We report here that an Arabidopsis () importin β, KETCH1 (karyopherin enabling the transport of the cytoplasmic HYL1), is critical for gametogenesis. Karyopherins are molecular chaperones mediating nucleocytoplasmic protein transport. However, the role of KETCH1 during gametogenesis is independent of HYPONASTIC LEAVES 1 (HYL1), a previously reported KETCH1 cargo. Instead, KETCH1 interacts with several RPs and is critical for the nuclear accumulation of RPL27a, whose mutations caused similar gametophytic defects. We further showed that knocking down caused reduced ribosome biogenesis and translational capacity, which may trigger the arrest of mitotic cell cycle progression and lead to gametophytic lethality.
雄性和雌性配子体是由小孢子或大孢子母细胞通过连续的减数分裂和有丝分裂细胞分裂产生的。这些分裂中的缺陷常常导致配子体致死。当编码核糖体相关蛋白的基因发生突变时，也会报告配子体致死。尽管已经根据与酵母和后生动物对应物的同源性在植物中鉴定出了许多核糖体蛋白（RPs），但 RPs 是如何被调节的，例如通过动态的亚细胞靶向，目前尚不清楚。我们在这里报告，拟南芥（）输入蛋白β，KETCH1（核孔蛋白，使细胞质 HYL1 能够运输），对配子发生至关重要。核输入蛋白是介导核质蛋白运输的分子伴侣。然而，KETCH1 在配子发生过程中的作用不依赖于 HYPONASTIC LEAVES 1（HYL1），这是以前报道的 KETCH1 货物。相反，KETCH1 与几个 RPs 相互作用，对于 RPL27a 的核积累至关重要，其突变导致类似的配子体缺陷。我们进一步表明，敲低 导致核糖体生物发生和翻译能力降低，这可能触发有丝分裂细胞周期进程的停滞，并导致配子体致死。
