University of Louisville

Poster Title

Gene Disruptions to Examine Interactions in Fungal Signal Transduction Pathways

Institution

University of Louisville

Abstract

The fungus, Ustilago maydis, is a pathogen of corn and an excellent model system for analyzing the interactions between host and pathogen. It is also useful for study of signal transduction pathways leading to development and differentiation of fungi. We have been examining two parallel pathways whereby externally-provided signals result in morphological changes, including the ability to cause disease on corn. The purpose of this project is to investigate how combinations of mutations in these pathways will affect the fungus in its development and interactions with its host. One pathway involves the MAPK protein kinase cascade, where successive phosphorylation of proteins leads to an alteration of gene expression. We found that both fungal mating and subsequent filamentation to penetrate host tissue require this pathway, which includes two necessary related kinases, Smu1 and Cla4. However, it is unknown how defects in both genes simultaneously would affect the fungus. The cAMP-dependent protein kinase A (PKA) pathway is a second route required for development. It appears linked to a program that senses available nitrogen and triggers a change in cell growth. Again, we want to generate mutations simultaneously in both parts of the pathway to assess how the components act in concert. We have employed a unique systematic approach to generate complete deletions of each gene alone or in combination with another player in the pathways we investigate. These studies will allow a clearer picture to emerge of the interplay between varied cellular proteins in fungal development leading to pathogenesis.

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Gene Disruptions to Examine Interactions in Fungal Signal Transduction Pathways

The fungus, Ustilago maydis, is a pathogen of corn and an excellent model system for analyzing the interactions between host and pathogen. It is also useful for study of signal transduction pathways leading to development and differentiation of fungi. We have been examining two parallel pathways whereby externally-provided signals result in morphological changes, including the ability to cause disease on corn. The purpose of this project is to investigate how combinations of mutations in these pathways will affect the fungus in its development and interactions with its host. One pathway involves the MAPK protein kinase cascade, where successive phosphorylation of proteins leads to an alteration of gene expression. We found that both fungal mating and subsequent filamentation to penetrate host tissue require this pathway, which includes two necessary related kinases, Smu1 and Cla4. However, it is unknown how defects in both genes simultaneously would affect the fungus. The cAMP-dependent protein kinase A (PKA) pathway is a second route required for development. It appears linked to a program that senses available nitrogen and triggers a change in cell growth. Again, we want to generate mutations simultaneously in both parts of the pathway to assess how the components act in concert. We have employed a unique systematic approach to generate complete deletions of each gene alone or in combination with another player in the pathways we investigate. These studies will allow a clearer picture to emerge of the interplay between varied cellular proteins in fungal development leading to pathogenesis.