In vivo binding by Arabidopsis SPLICING FACTOR 1 shifts 3′ splice-site choice, regulating circadian rhythms and immunity in plants

• 成果类型: Article
• 署名作者: Agrofoglio, Yamila Carla; Iglesias, Maria Jose; de Leone, Maria Jose; Hernando, Carlos Esteban; Lewinski, Martin; Torres, Sol Belen; Contino, Giuliana; Kohnke, Kim Joelle; Yanovsky, Marcelo Javier; Staiger, Dorothee; Mateos, Julieta Lisa
• 署名单位: University of Buenos Aires; Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET); Leloir Institute; University of Bielefeld
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.2531955123
• 发表日期: 2026-06-09
• 页码: e2531955123
• 关键词: splicing; arabidopsis; branch point; circadian clock; splice site; PRE-MESSENGER-RNA; FACTOR SF1; KH DOMAIN; clock; RECOGNITION; protein; reveals; RRM

摘要

Alternative splicing expands proteome diversity and enables phenotypic plasticity across eukaryotes. In plants, mutations in spliceosomal components impair development and stress responses, but the molecular mechanisms remain unclear. Here, we define the molecular function of SPLICING FACTOR 1 (AtSF1) in Arabidopsis thaliana using individual-nucleotide resolution UV crosslinking and immunoprecipitation combined with RNA sequencing of sf1 mutants. We identify the in vivo branch point sequences bound by AtSF1 and delineate its RNA-binding landscape, revealing pervasive splicing defects dominated by aberrant 3 ' splice-site selection. Structural comparison with human SF1 indicates that AtSF1 retains branch point recognition capacity but features a distinct domain organization, including a restructured C-terminal region absent in metazoans, suggesting a divergent RNA-binding mode that evolved to meet plant-specific splicing demands. AtSF1 targets are enriched for core circadian clock and defense genes, consistent with the long-period phenotype and immune-compromised phenotypes of sf1 mutants. Together, these findings establish that AtSF1 orchestrates alternative 3 ' splice-site choice through intron binding and branch point recognition, coupling RNA processing with circadian and immune regulation in plants.