title: Differential GC content between exons and introns establishes distinct strategies of splice-site recognition.
abstract: During evolution segments of homeothermic genomes underwent a GC content increase. Our analyses reveal that two exon-intron architectures have evolved from an ancestral state of low GC content exons flanked by short introns with a lower GC content. One group underwent a GC content elevation that abolished the differential exon-intron GC content, with introns remaining short. The other group retained the overall low GC content as well as the differential exon-intron GC content, and is associated with longer introns. We show that differential exon-intron GC content regulates exon inclusion level in this group, in which disease-associated mutations often lead to exon skipping. This group's exons also display higher nucleosome occupancy compared to flanking introns and exons of the other group, thus "marking" them for spliceosomal recognition. Collectively, our results reveal that differential exon-intron GC content is a previously unidentified determinant of exon selection and argue that the two GC content architectures reflect the two mechanisms by which splicing signals are recognized: exon definition and intron definition.
authors: Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine, Tel-Aviv University, Ramat Aviv 69978, Israel.
authors: Maayan
authors: M
authors: Amit
authors: Maya
authors: M
authors: Donyo
authors: Dror
authors: D
authors: Hollander
authors: Amir
authors: A
authors: Goren
authors: Eddo
authors: E
authors: Kim
authors: Sahar
authors: S
authors: Gelfman
authors: Galit
authors: G
authors: Lev-Maor
authors: David
authors: D
authors: Burstein
authors: Schraga
authors: S
authors: Schwartz
authors: Benny
authors: B
authors: Postolsky
authors: Tal
authors: T
authors: Pupko
authors: Gil
authors: G
authors: Ast
mesh_terms: D001482:Base Composition / Q000235:genetics*; D004247:DNA / Q000235:genetics; D004274:DNA, Recombinant / Q000235:genetics; D019143:Evolution, Molecular; D005091:Exons / Q000235:genetics*; D006801:Humans; D007438:Introns / Q000235:genetics*; D008957:Models, Genetic; D009154:Mutation / Q000235:genetics; D022821:RNA Splice Sites / Q000235:genetics*; D012326:RNA Splicing / Q000235:genetics*; D017381:Spliceosomes / Q000235:genetics
chemical_list: D004274:DNA, Recombinant; D022821:RNA Splice Sites; D004247:DNA