Horticultural Sciences Department, and Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, Florida 32611.
Department of Biological Sciences, Oakland University, Rochester, Michigan 48309.
Plant Cell. 2019 Mar;31(3):715-733. doi: 10.1105/tpc.18.00754. Epub 2019 Feb 13.
The last eukaryotic common ancestor had two classes of introns that are still found in most eukaryotic lineages. Common U2-type and rare U12-type introns are spliced by the major and minor spliceosomes, respectively. Relatively few splicing factors have been shown to be specific to the minor spliceosome. We found that the maize () RNA binding motif protein 48 (RBM48) is a U12 splicing factor that functions to promote cell differentiation and repress cell proliferation. RBM48 is coselected with the U12 splicing factor, zinc finger CCCH-type, RNA binding motif, and Ser/Arg rich 2/Rough endosperm 3 (RGH3). Protein-protein interactions between RBM48, RGH3, and U2 Auxiliary Factor (U2AF) subunits suggest major and minor spliceosome factors required for intron recognition form complexes with RBM48. Human RBM48 interacts with armadillo repeat containing 7 (ARMC7). Maize RBM48 and ARMC7 have a conserved protein-protein interaction. These data predict that RBM48 is likely to function in U12 splicing throughout eukaryotes and that U12 splicing promotes endosperm cell differentiation in maize.
最后一个真核生物的共同祖先拥有两类内含子，这两类内含子至今仍存在于大多数真核生物谱系中。常见的 U2 型内含子和罕见的 U12 型内含子分别由主要剪接体和次要剪接体进行剪接。已经证明，相对较少的剪接因子是次要剪接体所特有的。我们发现，玉米（）RNA 结合基序蛋白 48（RBM48）是一种 U12 剪接因子，它能够促进细胞分化并抑制细胞增殖。RBM48 与 U12 剪接因子、锌指 CCCH 型 RNA 结合基序和富含丝氨酸/精氨酸的 2/Rough 胚乳 3（RGH3）共选择。RBM48、RGH3 和 U2 辅助因子（U2AF）亚基之间的蛋白-蛋白相互作用表明，用于识别内含子的主要和次要剪接体因子与 RBM48 形成复合物。人类 RBM48 与富含角蛋白重复的 7（ARMC7）相互作用。玉米 RBM48 和 ARMC7 具有保守的蛋白-蛋白相互作用。这些数据预测，RBM48 可能在整个真核生物中发挥 U12 剪接的作用，并且 U12 剪接促进了玉米胚乳细胞的分化。
