Department of Molecular Genetics and Microbiology
Amino Acid Sequence; Binding Sites; Carrier Proteins; Cell Membrane; Hydrophobicity; Molecular Sequence Data; Protein Binding; Protein-Serine-Threonine Kinases; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; cdc42 GTP-Binding Protein
Life Sciences | Medicine and Health Sciences
The Rho-type GTPase Cdc42 is a central regulator of eukaryotic cell polarity and signal transduction. In budding yeast, Cdc42 regulates polarity and mitogen-activated protein (MAP) kinase signaling in part through the PAK-family kinase Ste20. Activation of Ste20 requires a Cdc42/Rac interactive binding (CRIB) domain, which mediates its recruitment to membrane-associated Cdc42. Here, we identify a separate domain in Ste20 that interacts directly with membrane phospholipids and is critical for its function. This short region, termed the basic-rich (BR) domain, can target green fluorescent protein to the plasma membrane in vivo and binds PIP(2)-containing liposomes in vitro. Mutation of basic or hydrophobic residues in the BR domain abolishes polarized localization of Ste20 and its function in both MAP kinase-dependent and independent pathways. Thus, Cdc42 binding is required but is insufficient; instead, direct membrane binding by Ste20 is also required. Nevertheless, phospholipid specificity is not essential in vivo, because the BR domain can be replaced with several heterologous lipid-binding domains of varying lipid preferences. We also identify functionally important BR domains in two other yeast Cdc42 effectors, Gic1 and Gic2, suggesting that cooperation between protein-protein and protein-membrane interactions is a prevalent mechanism during Cdc42-regulated signaling and perhaps for other dynamic localization events at the cell cortex.
DOI of Published Version
Mol Biol Cell. 2007 Dec;18(12):4945-56. Epub 2007 Oct 3. Link to article on publisher's site
Molecular biology of the cell
Takahashi, Satoe and Pryciak, Peter M., "Identification of novel membrane-binding domains in multiple yeast Cdc42 effectors" (2007). Open Access Articles. 1320.