Biology subjects

Tu, S.-L.

Publications and source records attributed to Tu, S.-L..

3 recordsLinked to original sources

bioRxiv2021

A high resolution single molecule sequencing-based Arabidopsis transcriptome using novel methods of Iso-seq analysis

BackgroundAccurate and comprehensive annotation of transcript sequences is essential for transcript quantification and differential gene and transcript expression analysis. Single molecule long read sequencing technologies provide improved integrity of transcript structures including alternative splicing, and transcription start and polyadenylation sites. However, accuracy is significantly affected by sequencing errors, mRNA degradation or incomplete cDNA synthesis. ResultsWe present a new and comprehensive Arabidopsis thaliana Reference Transcript Dataset 3 (AtRTD3). AtRTD3 contains over 160k transcripts - twice that of the best current Arabidopsis transcriptome and including over 1,500 novel genes. 79% of transcripts are from Iso-seq with accurately defined splice junctions and transcription start and end sites. We developed novel methods to determine splice junctions and transcription start and end sites accurately. Mis- match profiles around splice junctions provided a powerful feature to distinguish correct splice junctions and remove false splice junctions. Stratified approaches identified high confidence transcription start/end sites and removed fragmentary transcripts due to degradation. AtRTD3 is a major improvement over existing transcriptomes as demonstrated by analysis of an Arabidopsis cold response RNA-seq time-series. AtRTD3 provided higher resolution of transcript expression profiling and identified cold- and light-induced differential transcription start and polyadenylation site usage. ConclusionsAtRTD3 is the most comprehensive Arabidopsis transcriptome currently available. It improves the precision of differential gene and transcript expression, differential alternative splicing, and transcription start/end site usage from RNA-seq data. The novel methods for identifying accurate splice junctions and transcription start/end sites are widely applicable and will improve single molecule sequencing analysis from any species.

plant biology↗

bioRxiv2021

The U1 snRNP component RBP45d regulates temperature-responsive flowering in Arabidopsis thaliana

Pre-mRNA splicing is a crucial step of gene expression whereby the spliceosome produces constitutively and alternatively spliced transcripts that not only diversify the transcriptome but also play essential functions during plant development and responses to environmental changes. Numerous evidences indicate that regulation at the pre-mRNA splicing step is important for flowering time control, however the components and detailed mechanism underlying this process remain largely unknown. Here, we identified a previously unknown splicing factor in Arabidopsis thaliana, RNA BINDING PROTEIN 45d (RBP45d), a member of the RBP45/47 family. Using sequence comparison and biochemical analysis, we determined that RBP45d is a component of the U1 small nuclear ribonucleoprotein (U1 snRNP) with functions distinct from other family members. RBP45d associates with the U1 snRNP by interacting with pre-mRNA-processing factor 39a (PRP39a) and directly regulates alternative splicing (AS) for a specific set of genes. Plants with loss of RBP45d function exhibit defects in temperature-induced flowering potentially due to the mis-regulation of temperature-sensitive AS by RBP45d and PRP39a of the key flowering gene FLOWERING LOCUS M. Taken together, we report that RBP45d is a novel U1 snRNP component in plants that functions together with PRP39a in temperature-mediated flowering.

plant biology↗

bioRxiv2021

A new method to identify global targets of RNA-binding proteins in plants

BackgroundRNA-binding proteins (RBPs) play crucial roles in various aspects of post-transcriptional gene expression; their functions can vary between tissues, cell types, developmental stages, and environmental conditions. Identifying RBP target RNAs and investigating whether they are differentially bound by RBPs in different cell types, stages, or conditions could shed light on RBP functions. Although several strategies have been designed to identify RBP targets, they involve complicated biochemical steps and require large quantities of material, and only a few studies using these techniques have been performed in plants. The TRIBE (targets of RNA binding proteins identified by editing) method was recently developed to identify RBP targets using a RBP coupled to the catalytic domain of a Drosophila RNA editing enzyme and expressing this fusion protein in vivo. The resulting novel editing events can be identified by sequencing. This technique uses little material and does not require complex biochemical steps, however it is not yet adapted for use in plants. ResultsWe successfully applied an optimized genome-wide TRIBE method in plants. We selected the splicing regulator polypyrimidine tract-binding protein (PTB) as a model protein for testing the TRIBE system in the moss Physcomitrium patens. We demonstrated that 13.81% of protein-coding gene transcripts in P. patens are targets of PTB. Most potential PTB binding sites are located in coding sequences and 3 untranslated regions, suggesting that PTB performs multiple functions besides pre-mRNA splicing in this moss. In addition, TRIBE showed reproducible results compared to other methods. ConclusionsWe have developed an alternative method based on the TRIBE system to identify RBP targets in plants globally, and we provide guidance here for its application in plants.

plant biology↗