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Geranylgeranyltransferase Cwg2-Rho4/Rho5 module is implicated in the Pmk1 MAP kinase-mediated cell wall integrity

Akira Doi1, Ayako Kita, Yuki Kanda

  • 1Laboratory of Molecular Pharmacogenomics, School of Pharmaceutical Sciences, Kinki University, Kowakae 3-4-1, Higashi-Osaka, 577-8502, Japan; Japan Society for the Promotion of Science, 1-8 Chiyoda-ku, Tokyo, 102-8472, Japan.

Genes to Cells : Devoted to Molecular & Cellular Mechanisms
|February 6, 2015
PubMed

Insights

The study identifies Cwg2, a geranylgeranyltransferase I subunit, as crucial for Pmk1 MAPK pathway signaling in yeast. Impaired Cwg2 function disrupts small GTPase localization and affects cell wall integrity.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Yeast Genetics

Background:

  • Pmk1 MAPK pathway is essential for cell wall integrity in fission yeast.
  • Geranylgeranyltransferase I (GGTase I) modifies small GTPases for membrane localization.
  • Previous screens identified calcineurin and Pmk1 MAPK pathway regulators.

Purpose of the Study:

  • To identify novel regulators of the Pmk1 MAPK signaling pathway.
  • To investigate the role of Cwg2 in Pmk1 pathway function and cell wall integrity.
  • To elucidate the involvement of small GTPases Rho4 and Rho5 in Pmk1 signaling.

Main Methods:

  • Genetic screening for viable mutants (vic) in fission yeast.
  • Characterization of the vic2-1 mutant with a mutation in cwg2+.
  • Analysis of small GTPase localization using microscopy.
  • Assessing Pmk1 MAPK phosphorylation levels.
  • Investigating genetic interactions and protein associations.

Main Results:

  • The vic2-1 mutant harbors a mutation in cwg2+, encoding a GGTase I beta subunit.
  • Cwg2 is essential for proper localization of Rho1, Rho4, Rho5, and Cdc42 to cellular membranes.
  • Deletion of Rho4 and Rho5 phenocopies Cwg2 defects, including the vic phenotype and cell wall integrity issues.
  • Pmk1 MAPK phosphorylation is reduced in cwg2-v2, rho4-null, and rho5-null cells.
  • Rho4 and Rho5 associate with Pck1/Pck2.

Conclusions:

  • Cwg2 plays a critical role in the Pmk1 MAPK pathway by facilitating the membrane localization of key small GTPases.
  • Rho4 and Rho5 are important downstream effectors or regulators within the Pmk1 pathway, influencing cell wall integrity.
  • This study reveals a novel link between GGTase I activity and Pmk1 MAPK signaling in fission yeast.

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