Investigating the functionality of Opy2 extracellular Cysteine-Rich region in fMAPK pathway in S. cerevisiae

Sam Zheng

Yeast cells undergoing filamentous growth.

Yeast cells undergoing filamentous growth.

Undergraduate Student Project


What would our streets become if we did not have traffic lights? Cars bumping into each other and transportation would literally be paralyzed. Well, down to the molecular level, cells require likewise traffic order. Greetings! My name is Sam Zheng, a Junior Biology major student, and I've been doing research in Dr. Paul Cullen's lab at the Department of Biological Sciences since my freshman summer. One of the major focuses of Dr. Cullen lab's is to understand how cells can regulate signaling pathways in a complex and shared network. I was fortunate enough to start my independent project focusing on one key regulatory protein for the network - Opy2. Specifically, I'm interested in an extracellular region of the Opy2 found to be rich with amino acid cystines. I want to understand if this region is responsible for regulating multiple pathways and which part of it allows it to do so. Furthermore, if it is one part of the molecular traffic lights, what is the mechanism helping it to do its job?


The filamentous growth (fMAPK) pathway is an essential signaling pathway that allows fungal species to adapt to nutrient-depleted conditions and promote virulence in pathogenic strains. Notably, the fMAPK pathway shares regulatory proteins with other signaling pathways. We used Saccharomyces cerevisiae (i.e., Baker's yeast) to study an extracellular cysteine-rich region in the transmembrane protein Opy2 - a key regulatory protein that functions in multiple pathways. We hypothesize the cysteine-rich region is critical for the fMAPK pathway, and certain parts of the region are specifically important for the pathway. Genes were altered through site-directed mutagenesis and the fMAPK pathway was measured with transcriptional reporters by beta-galactosidase assays and colony growth. Our preliminary results identified cysteines required for Opy2 function in the filamentous growth pathway. Also, we found different cysteines affect the fMAPK level differently. Additional experiments are in progress to examine the role of the cysteine-rich region in pathway differentiation and opy2 localization.

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