A homolog of splicing factor SF1 is essential for development and is involved in the alternative splicing of pre‐mRNA in Arabidopsis thaliana

Abstract

SUMMARYDuring initial spliceosome assembly, SF1 binds to intron branch points and interacts with U2 snRNP auxiliary factor 65 (U2AF65). Here, we present evidence indicating that AtSF1, the Arabidopsis SF1 homolog, interacts with AtU2AF65a and AtU2AF65b, the Arabidopsis U2AF65 homologs. A mutant allele of AtSF1 (At5g51300) that contains a T-DNA insertion conferred pleiotropic developmental defects, including early flowering and abnormal sensitivity to abscisic acid. An AtSF1 promoter-driven GUS reporter assay showed that AtSF1 promoter activity was temporally and spatially altered, and that full AtSF1 promoter activity required a significant proportion of the coding region. DNA chip analyses showed that only a small proportion of the transcriptome was altered by more than twofold in either direction in the AtSF1 mutant. Expression of the mRNAs of many heat shock proteins was more than fourfold higher in the mutant strain; these mRNAs were among those whose expression was increased most in the mutant strain. An RT-PCR assay revealed an altered alternative splicing pattern for heat shock transcription factor HsfA2 (At2g26150) in the mutant; this altered splicing is probably responsible for the increased expression of the target genes induced by HsfA2. Altered alternative splicing patterns were also detected for the transcripts of other genes in the mutant strain. These results suggest that AtSF1 has functional similarities to its yeast and metazoan counterparts.

Herboxidiene triggers splicing repression and abiotic stress responses in plants

“…We recently showed that PB induces transcriptional patterns similar to those induced by a variety of abiotic stresses, and intriguingly, PB induces significant repression of splicing along with significant levels of intron retention [26]. To investigate whether GEX1A triggers similar responses, we tested its effects on the splicing of a select group of genes that are alternatively spliced under unfavorable growth conditions [28–30]. For these genes, GEX1A treatment resulted in reduced splicing efficiency, leading to splicing repression with IR (Fig.…”

AtU2AF65b functions in abscisic acid mediated flowering via regulating the precursor messenger RNA splicing of ABI5 and FLC in Arabidopsis

“…U2AF65 facilitates U2 snRNP recruitment and stabilizes the interaction of U2 snRNP with the branch point of intron during assembly of spliceosomal complex A (Guth et al, 1999;Chusainow et al, 2005). Mammalian U2AF65 contains three RRMs domains and an arginine/serine-rich (RS) domain (Will & Luhrmann, 2011;Jang et al, 2014). The first and second RRMs function in the recognition of the polypyrimidine tract of intron, and the third RRM (UHM) domain interacts with SF1, which binds the branch point of intron (Corsini et al, 2007).…”

SF1 Phosphorylation Enhances Specific Binding to U2AF 65 and Reduces Binding to 3′-Splice-Site RNA

“…The importance of the U2AF subunits for spliceosome assembly in mammals has been firmly established by biochemical reconstitution experiments (e.g., (15,16), among others). In contrast, SF1 selectively regulates splicing of a subset of introns (26)(27)(28)(29). One possible explanation is a transient role and rapid recycling of SF1 (30,31), such that trace amounts are sufficient to support splicing of traditional pre-mRNA substrates.…”