It's not just the poly(A) tail of A: A base purity affects protein translation efficiency| Genome Biology

Title: Impact of poly (A)-tail G-content on Arabidopsis PAB binding and their role in enhancing translational
journal:
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 and Xiaofeng Cao
Published time: 2019/09/03
DOI:
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poly (A) Tail is one of the most important features of the euthon nuclear mRNA, It is usually thought to consist of simple repetitions of adenotides (A). Recently,
teamed up with
to use a new poly (A) tail high-volume sequencing technique to reveal a new post-transcriptional regulatory mechanism for amoeba poly (A) tail mediatation , where bird nucleotides (G) scattered in poly (A) tails can reduce the translation efficiency of mRNA by inhibiting interactions with poly (A) binding proteins (PABs). The study was published
Journal.(A) tail has a key regulatory function for the poly (A) tail to the pornam rna and is an important determining element of its stability. Although poly(A) tails are important, accurate interpretation is difficult. The main technical barrier is that amplification of simple series of nucleotide sequences causes polymerases to slide, resulting in decoding and garbled sequencing results. In recent years, a number of high-volume sequencing techniques for mRNA tails have been gradually established: for example, PAL-seq estimates the poly(A) tail length of mRNA to be determined using a standard curve of samples of different poly (A) lengths. Tail-seq is an algorithm developed for the original image data of second generation sequencing, which infers the length and sequence of poly(A) tail by comparing with the standard. The results of Tail-seq in human cell line showed the presence of non-A nucleotides (G, U or C) in the tail of poly (A), with G accounting for the highest proportion. However, due to the difficulty of obtaining further mutants, there are still few reports of the molecular function and mechanism of action of G in poly (A) tail.
In this study, the researchers extracted high-quality sequencing information by sequencing the full-length poly (A) tail and developing downstream bioinsynomic algorithms, and found that non-A nucleotides were also present in the poly (A) tail of the model plant athropophymes, and also had the highest G content. The researchers then constructed a series of important mutants using AtPAB2, AtPAB4, and AtPAB8, core members of the amoeba poly (A) binding protein family.this study, by further integrating high-volume experimental techniques such as CLIP-seq, ribo-seq, and mRNA stability detection, systematically studied the molecular biology function of poly(A) tail and its binding protein PAB at the whole genome level, and came to the following conclusions:
1. AtPAB is widely combined with the poly(A) tail of mRNA in plants, but there are significant differences in the binding efficiency of different mRNA;
2. The poly (A) tail of 10% of the athropophymethyst mustard contains at least one G, with a distribution range of 0.8-28% in different mRNA;
3. The difference between AtPAB and different mRNA can be explained in part by the difference in G content in the tail of poly (A) - the higher the "purity" of A, the stronger its binding to atPAB;
4. The combination of AtPAB to mRNA can improve the translation efficiency of mRNA.
5. Correspondingly, in
mutants, the reduction in the translation efficiency of mRNA with G-free

"pure poly (A) tail
" is more pronounced;, the study fully demonstrates the powerful advantages of the combination of second-generation sequencing technology and bio-informational algorithms in the process of analyzing biometric regulation. The results illustrate that the G content in plant poly (A) tail can affect protein translation efficiency by inhibiting PAB binding, which is the expansion and innovation of the central law of modern molecular biology. This study is of great reference value for exploring the mechanism of post-transcription regulation of mRNA in other species.
Geneological and Developmental Biology Institute of China
and
are co-authors of the paper; Dr.
and
are co-authors; and the Liu Chunming Research Group of the
Plant Institute and the
Research Group of the University of Pennsylvania are involved in the research. The research was supported by the National Natural Science Foundation of China, the Ministry of Science and Technology,
National Key Laboratory of Chinese Science and Technology and Plant Genomics.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.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.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.
(Source: Science.com)