Description
- Abstract:
- Gamete fusion is an essential step in sexual reproduction, requiring the merger of plasma membranes and genetic material from two gametes to produce a single zygote. Fusion proteins function directly in vesicle, viral, and cell-cell fusion events, by providing a mechanism to drive two membranes closer together and promote lipid mixing. HAP2 is a gamete-specific cell fusion protein, and it is required for fusion in a broad range of eukaryotic organisms, including the flowering plant Arabidopsis thaliana. I have identified the membrane interaction surface of HAP2 from Arabidopsis thaliana as an amphipathic helix, and I identified a cluster of hydrophobic residues with this fusion helix that are required for HAP2 function in gamete fusion. I have demonstrated functional conservation of this fusion helix in flowering plants. I also ectopically expressed HAP2 in female gametes as a method to further interrogate the sufficiency of HAP2 to mediate fusion in plant cells. Since HAP2 is structurally homologous to class II viral fusion proteins, which require a change in pH to initiate fusion, I investigated potential pH changes in the environment surrounding the sperm before and during fusion. My results suggest the sperm are exposed to different pH environments, including a potential decrease in pH after release from the pollen tube to the site of fusion. Altogether, my analysis revealed important insights into how Arabidopsis HAP2 interacts with a target membrane via the hydrophobic face of an amphipathic helix and provides several opportunities to further investigate the HAP2-mediated gamete fusion mechanism, including analysis of the gamete fusion environment and modes of HAP2 sufficiency. Furthermore, my research highlights the importance of understanding how HAP2 is regulated and how that regulation may differ across species that undergo gamete fusion in a variety of sexual environments.
- Notes:
- Thesis (Ph. D.)--Brown University, 2018
Access Conditions
- Rights
- In Copyright
- Restrictions on Use
- All rights reserved. Collection is open to the Brown community for research.
Citation
Forcina, Jennifer,
"Functional Analysis of HAP2 Reveals Insights into a Gamete Fusion Mechanism"
(2018).
Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.26300/xb83-gt55
Relations
Collection:
-
Molecular Biology, Cell Biology, and Biochemistry Theses and Dissertations
Theses and Dissertations for the Molecular Biology, Cell Biology, and Biochemistry department....