Cell Polarity Processes in Yeast Requiring a Novel Paxillin-like Protein

Syracuse University, Syracuse NY

Investigators

Abstract

The mechanisms that nucleate and maintain cell polarity cues at distinct sites of the eucaryotic cell cortex remain poorly understood. In higher eucaryotes, a class of proteins which includes vertebrate paxillin act as adapter proteins or molecular scaffolds, organizing proteins controlling signaling and cytoskeletal reorganization. Paxillin is localized to focal adhesions, sites of signaling and cytoskeletal rearrangement, due to the presence of motifs termed LIM domains that occur in the carboxy terminus of the protein. Preliminary studies have been performed of a novel yeast gene, YKR090w, that encodes a protein which contains LIM domains similar to those found in paxillin. Preliminary data indicate that the gene functions in cell polarity events during the yeast life cycle and that a GFP fusion to the gene product localizes to sites of polarized cell growth. The gene has been named gene PXL1 (Paxillin-like protein 1) because of its similarity to paxillin in sequence, localization and general function in cell polarity. Studies will be performed to determine the mechanism by which the PXL1 gene product, Pxl1p, becomes localized at polarized growth sites. A major focus of the studies will be to identify proteins that are associated with Pxl1p and that may participate in its function in cell polarity, particularly with respect to Rho1 pathway function. The interactions of these proteins with Pxl1p will be characterized by biochemical, genetic and cell biological methods. Graduate students and undergraduate researchers will receive training through the proposed activities. These studies are expected to increase our understanding of the role of LIM domains in regulators of the eucaryotic cytoskeleton and to further our knowledge of the mechanisms that localize and assemble cell polarity proteins at sites of signaling and cytoskeletal reorganization.