title: Alternatively spliced, spliceosomal twin introns in Helminthosporium solani.
abstract: Spliceosomal twin introns, "stwintrons", have been defined as complex intervening sequences that carry a second intron ("internal intron") interrupting one of the conserved sequence domains necessary for their correct splicing via consecutive excision events. Previously, we have described and experimentally verified stwintrons in species of Sordariomycetes, where an "internal intron" interrupted the donor sequence of an "external intron". Here we describe and experimentally verify two novel stwintrons of the potato pathogen Helminthosporium solani. One instance involves alternative splicing of an internal intron interrupting the donor domain of an external intron and a second one interrupting the acceptor domain of an overlapping external intron, both events leading to identical mature mRNAs. In the second case, an internal intron interrupts the donor domain of the external intron, while an alternatively spliced intron leads to an mRNA carrying a premature chain termination codon. We thus extend the stwintron concept to the acceptor domain and establish a link of the occurrence of stwintrons with that of alternative splicing.
authors.affiliation: Dept. of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Norbert
authors.initials: N
authors.lastname: Ág
authors.affiliation: Dept. of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary. Electronic address: drir.michelflipphi@gmail.com.
authors.forename: Michel
authors.initials: M
authors.lastname: Flipphi
authors.affiliation: Dept. of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Levente
authors.initials: L
authors.lastname: Karaffa
authors.affiliation: Dept. of Microbiology, Imperial College, London SW7 2AZ, United Kingdom; Institut de Biologie Intégrative de la Cellule (I2BC), UMR CEA/CNRS/Université Paris-Sud, 91405 Orsay Cedex, France.
authors.forename: Claudio
authors.initials: C
authors.lastname: Scazzocchio
authors.affiliation: Dept. of Biochemical Engineering, Faculty of Science and Technology, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Erzsébet
authors.initials: E
authors.lastname: Fekete
mesh_terms: D017398:Alternative Splicing; D017124:Conserved Sequence; D006375:Helminthosporium / Q000235:genetics*; D007438:Introns / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D017381:Spliceosomes / Q000235:genetics*
chemical_list: D012333:RNA, Messenger
keywords: Alternative splicing; Filamentous ascomycetes; Helminthosporium solani; Premature stop codon; Sequential splicing; Spliceosomal twin introns