hap2(gcs1)-dependent gamete fusion requires a positively charged carboxy-terminal domainhap2(gcs1)端依赖配子融合需要一个带正电的carboxy-terminal域.pdfVIP

HAP2(GCS1)-Dependent Gamete Fusion Requires a Positively Charged Carboxy-Terminal Domain Julian L. Wong, Alexander R. Leydon, Mark A. Johnson* Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, Rhode Island, United States of America Abstract HAP2(GCS1) is a deeply conserved sperm protein that is essential for gamete fusion. Here we use complementation assays to define major functional regions of the Arabidopsis thaliana ortholog using HAP2(GCS1) variants with modifications to regions amino(N) and carboxy(C) to its single transmembrane domain. These quantitative in vivo complementation studies show that the N-terminal region tolerates exchange with a closely related sequence, but not with a more distantly related plant sequence. In contrast, a distantly related C-terminus is functional in Arabidopsis, indicating that the primary sequence of the C-terminus is not critical. However, mutations that neutralized the charge of the C-terminus impair HAP2(GCS1)- dependent gamete fusion. Our results provide data identifying the essential functional features of this highly conserved sperm fusion protein. They suggest that the N-terminus functions by interacting with female gamete-expressed proteins and that the positively charged C-terminus may function through electrostatic interactions with the sperm plasma membrane. Citation: Wong JL, Leydon AR, Johnson MA (2010) HAP2(GCS1)-Dependent Gamete Fusion Requires a Positively Charged Carboxy-Terminal Domain. PLoS Genet 6(3): e1000882. doi:10.1371/journal.pgen.1000882 Editor: Gregory S. Barsh, Stanford University School of Medicine, United States of America Received October 28, 2009; Accepted February 12, 2010; Published March 19, 2010 Copyright: 2010 Wong et al. This is an open-access article distributed under the