Functional Analysis of a Putative Signal Transduction Receptor Required for Mating in Tetrahymena

Marquette University, Milwaukee WI

Investigators

Abstract

Almost all cells read and respond to signals from the environment or from neighboring cells. The signal interacts with a signal receptor protein on the cell membrane. That interaction initiates a series of chemical reactions within the responding cell that determine its developmental fate and ultimate identity. The mating interactions between cells of the protozoan Tetrahymena provide a good model system to study signaling between cells because, in Tetrahymena, it is possible to specifically remove or "knock out" a gene of interest. By observing the behavior of the knockout cell lines, it is possible to determine what processes require the activity of that gene. Furthermore, specific regions of a gene that are essential for its activity, can be identified by replacing the gene with a slightly modified version of the same gene. A gene has been identified that is specifically active during sexual reproduction in Tetrahymena. The structure of the protein encoded by the gene, MCP1, was deduced from the gene sequence and comparison to known proteins. Structural analysis suggests that the gene encodes a signal receptor. The project has two specific goals. 1.) To determine whether MCP1 is required for mating in Tetrahymena. If so, mating knockout cells will be studied microscopically and biochemically to determine precisely what part of the mating process is defective in MCP1 knockouts. 2.) Specific predictions of the signal receptor model will be tested, including whether the gene product is a membrane protein. The broader impacts of the study will be primarily in the training of students at both the graduate and undergraduate levels. Two Ph.D candidates are currently doing dissertation research on the project. The laboratory tradition of independent research for undergraduates will continue. In the past, several of these students have published in peer-reviewed journals and/or gone on to postgraduate studies.