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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
PubMed

Insights

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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