论文标题：Impact of poly(A)-tail G-content on Arabidopsis PAB binding and their role in enhancing translational efficiency
期刊：Genome Biology
作者：Taolan Zhao, Qing Huan, Jing Sun, Chunyan Liu, Xiuli Hou, Xiang Yu, Ian M. Silverman, Yi Zhang, Brian D. Gregory, Chun-Ming Liu, Wenfeng Qian Xiaofeng Cao
中国科学院遗传与发育生物学研究所曹晓风研究员和钱文峰研究员为论文的共同通讯作者；肇涛澜、郇庆、孙婧和刘春艳博士为共同第一作者；中科院植物所刘春明研究组、美国宾夕法尼亚大学Brian D. Gregory研究组参与了相关的研究工作。该研究得到国家自然科学基金委、科技部、中国科学院与植物基因组学国家重点实验室的资助。
摘要：
Background
Polyadenylation plays a key role in producing mature mRNAs in eukaryotes. It is widely believed that the poly(A)-binding proteins (PABs) uniformly bind to poly(A)-tailed mRNAs, regulating their stability and translational efficiency.
Results
We observe that the homozygous triple mutant of broadly expressed Arabidopsis thaliana PABs, AtPAB2, AtPAB4, and AtPAB8, is embryonic lethal. To understand the molecular basis, we characterize the RNA-binding landscape of these PABs. The AtPAB-binding efficiency varies over one order of magnitude among genes. To identify the sequences accounting for the variation, we perform poly(A)-seq that directly sequences the full-length poly(A) tails. More than 10% of poly(A) tails contain at least one guanosine (G); among them, the G-content varies from 0.8 to 28%. These guanosines frequently divide poly(A) tails into interspersed A-tracts and therefore cause the variation in the AtPAB-binding efficiency among genes. Ribo-seq and genome-wide RNA stability assays show that AtPAB-binding efficiency of a gene is positively correlated with translational efficiency rather than mRNA stability. Consistently, genes with stronger AtPAB binding exhibit a greater reduction in translational efficiency when AtPAB is depleted.
Conclusions
Our study provides a new mechanism that translational efficiency of a gene can be regulated through the G-content-dependent PAB binding, paving the way for a better understanding of poly(A) tail-associated regulation of gene expression.
