New publication on gamete fusion from the Sprunck lab, in collaboration with the M.-X. Sun lab in Wuhan, China.
DMP8 and 9 regulate HAP2/GCS1 trafficking for the timely acquisition of sperm fusion competence.
PNAS 119, Vol. 45, e2207608119. doi.org/10.1073/pnas.2207608119
Wei Wang, Hanxian Xiong, Philipp Cyprys, Raphael Malka, María Flores-Tornero, Peng Zhao, Xiongbo Peng, Stefanie Sprunck, Meng-Xiang Sun (2022).
Sexual reproduction involves the fusion of two gametes of opposite sex. Although the sperm-expressed fusogen HAPLESS 2 (HAP2) or GENERATIVE CELL SPECIFIC 1 (GCS1) plays a vital role in this process in many eukaryotic organisms and an understanding of its regulation is emerging in unicellular systems [J. Zhang et al., Nat. Commun. 12, 4380 (2021); J. F. Pinello et al. Dev. Cell 56, 3380–3392.e9 (2021)], neither HAP2/GCS1 interactors nor mechanisms for delivery and activation at the fusion site are known in multicellular plants. Here, we show that Arabidopsis thaliana HAP2/GCS1 interacts with two sperm DUF679 membrane proteins (DMP8 and DMP9), which are required for the EGG CELL 1 (EC1)-induced translocation of HAP2/GCS1 from internal storage vesicle to the sperm plasma membrane to ensure successful fertilization. Our studies in Arabidopsisand tobacco provide evidence for a conserved function of DMP8/9-like proteins as HAP2/GCS1 partner in seed plants. Our data suggest that seed plants evolved a DMP8/9-dependent fusogen translocation process to achieve timely acquisition of sperm fusion competence in response to egg cell–derived signals, revealing a previously unknown critical step for successful fertilization.
