Cell fusion and fusion induced lysis in Neurospora crassa: Role of the SO protein and its potential interaction partners

• Applicant: Professor Dr. André Fleißner
• Subject Area: Plant Genetics and Genomics
• Term: from 2009 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 157351802

Cell-cell fusion is an essential process for the propagation and development of most eukaryotic organisms. Despite their variable biological functions and the diversity of cells involved, most fusion events share common biological principles. The fusion partners have to recognize each other, establish physical contact, degrade extra cellular matrix or cell wall and finally merge their plasma membranes. Plasma membrane merger always comes with the risk of cell lysis, suggesting that mechanisms minimizing this risk must exist. The molecular mechanisms controlling these cellular reactions are only poorly understood.In the model system Neurospora crassa, we identified an unusual mechanism of fusion cell communication. The two fusion partners appear to switch between two physiological stages, probably related to signal sending and receiving, in a highly coordinated, alternating manner. This process involves the activity of two MAP kinase signaling cascades (MAK-1 and MAK-2) and SO, a protein of unknown molecular function. Recently, we identified an additional process employing the SO protein. Together with its interaction partner PEF-1, SO is recruited to sites of plasma membrane damage in lysing cells. This reaction can be induced either by lysis occuring in association with cell fusion, but also by addition of polyen fungicides, which cause pore formation. In the proposed project, we will further investigate the role of SO and its interaction partners in cell fusion and the membrane damage response. By using a combination of classical and molecular genetics, biochemical analysis, fluorescent microscopy and live cell imaging we will further characterize the function, subcellular localization and dynamic of these factors. By using yeast two hybrid assays and immunoprecipitation and mass spectrometry we will analyze the molecular composition of SO and PEF-1 complexes. Furthermore, we will investigate the functional relationship between SO and the MAP kinase cascades.The results of this study will further our understanding of eukaryotic cell fusion, the cellular response to membrane damage and the fungal reaction to polyen antibiotics.

• DFG Programme: Research Grants
• Participating Person: Dr. Ines Teichert