RNA Recognition-like Motifs Activate a Mitogen-Activated Protein Kinase
Timothy Phillips1, Chong Wai Tio1, Gregory Omerza1
1Department of Biochemistry and Molecular Biology , Thomas Jefferson University , Philadelphia , Pennsylvania 19107 , United States.
Biochemistry
|November 20, 2018
Summary
RNA recognition motif-like domains in Ssp2 protein directly activate the Smk1 mitogen-activated protein kinase (MAPK) in yeast, controlling spore formation. These findings reveal a novel mechanism for protein kinase activation.
Area of Science:
- Molecular Biology
- Yeast Genetics
- Protein Kinase Signaling
Background:
- Smk1 (MAPK) regulates yeast spore formation.
- Ssp2 protein activates Smk1 during meiosis.
Purpose of the Study:
- To investigate the structural basis of Ssp2's activation of Smk1.
- To determine the role of RNA recognition motif (RRM)-like domains in Ssp2 activity.
Main Methods:
- Site-directed mutagenesis of Ssp2.
- Bacterial expression and purification of Ssp2 fragments.
- In vitro kinase assays.
- Cross-linking experiments.
Main Results:
- A fragment of Ssp2 containing two RRM-like motifs activates Smk1.
- Mutations in these motifs abolish Ssp2 activity.
- RRM-like motifs expressed separately activate Smk1.
- Motifs bind Smk1 near the ATP-binding pocket.
Conclusions:
- RRM-like motifs are essential for Ssp2-mediated Smk1 activation.
- These motifs directly interact with Smk1 to trigger kinase activity.
- This study uncovers a novel function for RRM-like domains in direct protein kinase activation.
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