TY - JOUR
T1 - Intra-domain cross-talk regulates serine-arginine protein kinase 1-dependent phosphorylation and splicing function of transformer 2β1
AU - Jamros, Michael A.
AU - Aubol, Brandon E.
AU - Keshwani, Malik M.
AU - Zhang, Zhaiyi
AU - Stamm, Stefan
AU - Adams, Joseph A.
N1 - Publisher Copyright:
© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.
PY - 2015/7/10
Y1 - 2015/7/10
N2 - Transformer 2β1 (Tra2β1) is a splicing effector protein composed of a core RNA recognition motif flanked by two arginineserine-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.
AB - Transformer 2β1 (Tra2β1) is a splicing effector protein composed of a core RNA recognition motif flanked by two arginineserine-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.
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U2 - 10.1074/jbc.M115.656579
DO - 10.1074/jbc.M115.656579
M3 - Article
C2 - 26013829
AN - SCOPUS:84940094447
SN - 0021-9258
VL - 290
SP - 17269
EP - 17281
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 28
ER -