The U6 Biogenesis-Like I Plays an Important Role in Maize Kernel and Seedling Development by Affecting the 3＇ End Processing of U6 snRNA

• Published in: 分子植物：英文版 Vol. 10; no. 3; pp. 470 - 482
• Main Author: Jiankun Li Junjie Fu Yan Chen Kaijian Fan Cheng He Zhiqiang Zhang Li Li Yunjun Liu Jun Zheng Dongtao Ren Guoying Wang
• Format: Journal Article
• Language: English
• Published: 2017
• Subjects: RNA剪接; snRNA; 幼苗生长发育; 核酸外切酶; 玉米籽粒; 生物合成; 突变等位基因; 调控基因表达
• ISSN: 1674-2052

Regulation of gene expression at the post-transcriptional level is of crucial importance in the development of an organism. Here we present the characterization of a maize gene, U6 biogenesis-like 1 （UBL1）, which plays an important role in kernel and seedling development by influencing pre-mRNA splicing. The ubll mutant, exhibiting small kernel and weak seedling, was isolated from a Mutator-tagged population. Trans- genic complementation and three independent mutant alleles confirmed that UBL1, which encodes a putative RNA exonuclease belonging to the 2H phosphodiesterase superfamily, is responsible for the phenotype of ubll. We demonstrated that UBL1 possess the RNA exonuclease activity in vitro and found that loss of UBL1 function in ubll causes decreased level and abnormal 3＇ end constitution of snRNA U6, resulting in splicing defect of mRNAs. Through the in vitro and in vivo studies replacing two histidines with alanines in the H-X-T/S-X （X is a hydrophobic residue） motifs we demonstrated that these two motifs are essential for the normal function of UBL1. We further showed that the function of UBL1 may be conserved across a wide phylogenetic distance as the heterologous expression of maize UBL1 could complement the Arabidopsis ubll mutant.