Intra-domain Cross-talk Regulates Serine-arginine Protein Kinase 1-dependent Phosphorylation and Splicing Function of Transformer 2β1.

TitleIntra-domain Cross-talk Regulates Serine-arginine Protein Kinase 1-dependent Phosphorylation and Splicing Function of Transformer 2β1.
Publication TypeJournal Article
Year of Publication2015
JournalThe Journal of biological chemistry
Volume290
Issue28
Pagination17269-81
Date Published2015 Jul 10
ISSN0021-9258
AbstractTransformer 2β1 (Tra2β1) is a splicing effector protein composed of a core RNA recognition motif flanked by two arginine-serine-rich (RS) domains, RS1 and RS2. Although Tra2β1-dependent splicing is regulated by phosphorylation, very little is known about how protein kinases phosphorylate these two RS domains. We now show that the serine-arginine protein kinase-1 (SRPK1) is a regulator of Tra2β1 and promotes exon inclusion in the survival motor neuron gene 2 (SMN2). To understand how SRPK1 phosphorylates this splicing factor, we performed mass spectrometric and kinetic experiments. We found that SRPK1 specifically phosphorylates 21 serines in RS1, a process facilitated by a docking groove in the kinase domain. Although SRPK1 readily phosphorylates RS2 in a splice variant lacking the N-terminal RS domain (Tra2β3), RS1 blocks phosphorylation of these serines in the full-length Tra2β1. Thus, RS2 serves two new functions. First, RS2 positively regulates binding of the central RNA recognition motif to an exonic splicing enhancer sequence, a phenomenon reversed by SRPK1 phosphorylation on RS1. Second, RS2 enhances ligand exchange in the SRPK1 active site allowing highly efficient Tra2β1 phosphorylation. These studies demonstrate that SRPK1 is a regulator of Tra2β1 splicing function and that the individual RS domains engage in considerable cross-talk, assuming novel functions with regard to RNA binding, splicing, and SRPK1 catalysis.
URLhttp://www.jbc.org/cgi/pmidlookup?view=long&pmid=26013829
DOI10.1074/jbc.M115.656579
PubMed Linkhttp://www.ncbi.nlm.nih.gov/pubmed/26013829?dopt=Abstract
Short TitleJ Biol Chem