Distinct mechanisms govern the phosphorylation of different SR protein splicing factors
| Autor: | Kristen Wing Yu Yung, Gordon Ho Ching Chan, Terrence Chi-Kong Lau, Chuyue Zeng, Jacky Chi Ki Ngo, Yunxin Long, Carmen O. K. Law, Weng Hong Sou, Haizhen Liu, Stephanie Winn Chee Wan, Qingyun Li |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Models
Molecular 0301 basic medicine Serine threonine protein kinase Protein Serine-Threonine Kinases SRPK1 Biochemistry Dephosphorylation 03 medical and health sciences SR protein Humans Protein phosphorylation Amino Acid Sequence Phosphorylation Protein kinase A Molecular Biology Serine-Arginine Splicing Factors 030102 biochemistry & molecular biology Kinase Chemistry fungi Cell Biology Cell biology HEK293 Cells 030104 developmental biology Enzymology Sequence Alignment |
| Zdroj: | Journal of Biological Chemistry. 294:1312-1327 |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.ra118.003392 |
| Popis: | Serine-arginine (SR) proteins are essential splicing factors containing a canonical RNA recognition motif (RRM), sometimes followed by a pseudo-RRM, and a C-terminal arginine/serine-rich (RS) domain that undergoes multisite phosphorylation. Phosphorylation regulates the localization and activity of SR proteins, and thus may provide insight into their differential biological roles. The phosphorylation mechanism of the prototypic SRSF1 by serine-arginine protein kinase 1 (SRPK1) has been well-studied, but little is known about the phosphorylation of other SR protein members. In the present study, interaction and kinetic assays unveiled how SRSF1 and the single RRM–containing SRSF3 are phosphorylated by SRPK2, another member of the SRPK family. We showed that a conserved SRPK-specific substrate-docking groove in SRPK2 impacts the binding and phosphorylation of both SR proteins, and the localization of SRSF3. We identified a nonconserved residue within the groove that affects the kinase processivity. We demonstrated that, in contrast to SRSF1, for which SRPK-mediated phosphorylation is confined to the N-terminal region of the RS domain, SRSF3 phosphorylation sites are spread throughout its entire RS domain in vitro. Despite this, SRSF3 appears to be hypophosphorylated in cells at steady state. Our results suggest that the absence of a pseudo-RRM renders the single RRM–containing SRSF3 more susceptible to dephosphorylation by phosphatase. These findings suggest that the single RRM– and two RRM–containing SR proteins represent two subclasses of phosphoproteins in which phosphorylation statuses are maintained by unique mechanisms, and pose new directions to explore the distinct roles of SR proteins in vivo. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|