title: Microexon-based regulation of ITSN1 and Src SH3 domains specificity relies on introduction of charged amino acids into the interaction interface.
abstract: SH3 domains function as protein-protein interaction modules in assembly of signalling and endocytic protein complexes. Here we report investigations of the mechanism of regulation of the binding properties of the SH3 domains of intersectin (ITSN1) and Src kinase by alternative splicing. Comparative sequence analysis of ITSN1 and Src genes revealed the conservation of alternatively spliced microexons affecting the structure of the SH3 domains in vertebrates. We show that neuron-specific ITSN1 transcripts containing the microexon 20 that encodes five amino acid residues within the SH3A domain are expressed in zebrafish from the earliest stages of the development of the nervous system. Models of alternative isoforms of the ITSN1 SH3A domain revealed that the insertion encoded by the microexon is located at the beginning of the n-Src loop of this domain causing a shift of negatively charged amino acids towards the interaction interface. Mutational analysis confirmed the importance of translocation of these negatively charged amino acids for interaction with dynamin 1. We also identified a residue within the microexon-encoded insert in the SH3 domain of brain-specific variant of Src that abolishes interaction of the domain with dynamin 1. Thus microexons provide a mechanism for the control of tissue-specific interactions of ITSN1 and Src with their partners.
authors.affiliation: Institute of Molecular Biology and Genetics, 150 Zabolotnogo Street, Kyiv 03680, Ukraine. m.dergai@gmail.com
authors.forename: Mykola
authors.initials: M
authors.lastname: Dergai
authors.forename: Lyudmila
authors.initials: L
authors.lastname: Tsyba
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Dergai
authors.forename: Igor
authors.initials: I
authors.lastname: Zlatskii
authors.forename: Inessa
authors.initials: I
authors.lastname: Skrypkina
authors.forename: Vitalii
authors.initials: V
authors.lastname: Kovalenko
authors.forename: Alla
authors.initials: A
authors.lastname: Rynditch
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism*; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D000818:Animals; D005091:Exons; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009420:Nervous System / Q000254:growth & development / Q000378:metabolism; D014158:Transcription, Genetic; D015027:Zebrafish; D018909:src Homology Domains; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; D000596:Amino Acids; C485568:ITSN1 protein, human; D019061:src-Family Kinases