Systematic characterization of the branch point binding protein, splicing factor 1, gene family in plant development and stress responses

Background: Among eukaryotic organisms, alternative splicing is an important process that can generate multiple transcripts from one same precursor messenger RNA, which greatly increase transcriptome and proteome diversity. This process is carried out by a super-protein complex defined as the spliceosome. Specifically, splicing factor 1/branchpoint binding protein (SF1/BBP) is a single protein that can bind to the intronic branchpoint sequence (BPS), connecting the 5′ and 3′ splice site binding complexes during early spliceosome assembly. The molecular function of this protein has been extensively investigated in yeast, metazoa and mammals. However, its counterpart in plants has been seldomly reported. Results: To this end, we conducted a systematic characterization of the SF1 gene family across plant lineages. In this work, a total of 92 sequences from 59 plant species were identified. Phylogenetic relationships of these sequences were constructed, and subsequent bioinformatic analysis suggested that this family likely originated from an ancient gene transposition duplication event. Most plant species were shown to maintain a single copy of this gene. Furthermore, an additional RNA binding motif (RRM) existed in most members of this gene family in comparison to their animal and yeast counterparts, indicating that their potential role was preserved in the plant lineage. Conclusion: Our analysis presents general features of the gene and protein structure of this splicing factor family and will provide fundamental information for further functional studies in plants.