Abstract
The molecular mechanisms of the defining event in fertilization, gamete fusion, remain poorly understood. The FUS1 gene in the unicellular, biflagellated green alga Chlamydomonas is one of the few sex-specific eukaryotic genes shown by genetic analysis to be essential for gamete fusion during fertilization. In Chlamydomonas, adhesion and fusion of the plasma membranes of activated mt+ and mt- gametes is accomplished via specialized fusion organelles called mating structures. Herein, we identify the endogenous Fus1 protein, test the idea that Fus1 is at the site of fusion, and identify the step in fusion that requires Fus1. Our results show that Fus1 is a ∼95-kDa protein present on the external surface of both unactivated and activated mt+ gametes. Bioassays indicate that adhesion between mating type plus and mating type minus fusion organelles requires Fus1 and that Fus1 is functional only after gamete activation. Finally, immunofluorescence demonstrates that the Fus1 protein is present as an apical patch on unactivated gametes and redistributes during gamete activation over the entire surface of the microvillous-like activated plus mating structure, the fertilization tubule. Thus, Fus1 is present on mt+ gametes at the site of cell-cell fusion and essential for an early step in the fusion process.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 2530-2542 |
| Number of pages | 13 |
| Journal | Molecular Biology of the Cell |
| Volume | 14 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 1 2003 |
Fingerprint
ASJC Scopus subject areas
- Molecular Biology
- Genetics
- Cell Biology
Cite this
The Chlamydomonas Fus1 protein is present on the mating type plus fusion organelle and required for a critical membrane adhesion event during fusion with minus gametes. / Misamore, Michael J.; Gupta, Surabhi; Snell, William J.
In: Molecular Biology of the Cell, Vol. 14, No. 6, 01.06.2003, p. 2530-2542.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The Chlamydomonas Fus1 protein is present on the mating type plus fusion organelle and required for a critical membrane adhesion event during fusion with minus gametes
AU - Misamore, Michael J.
AU - Gupta, Surabhi
AU - Snell, William J.
PY - 2003/6/1
Y1 - 2003/6/1
N2 - The molecular mechanisms of the defining event in fertilization, gamete fusion, remain poorly understood. The FUS1 gene in the unicellular, biflagellated green alga Chlamydomonas is one of the few sex-specific eukaryotic genes shown by genetic analysis to be essential for gamete fusion during fertilization. In Chlamydomonas, adhesion and fusion of the plasma membranes of activated mt+ and mt- gametes is accomplished via specialized fusion organelles called mating structures. Herein, we identify the endogenous Fus1 protein, test the idea that Fus1 is at the site of fusion, and identify the step in fusion that requires Fus1. Our results show that Fus1 is a ∼95-kDa protein present on the external surface of both unactivated and activated mt+ gametes. Bioassays indicate that adhesion between mating type plus and mating type minus fusion organelles requires Fus1 and that Fus1 is functional only after gamete activation. Finally, immunofluorescence demonstrates that the Fus1 protein is present as an apical patch on unactivated gametes and redistributes during gamete activation over the entire surface of the microvillous-like activated plus mating structure, the fertilization tubule. Thus, Fus1 is present on mt+ gametes at the site of cell-cell fusion and essential for an early step in the fusion process.
AB - The molecular mechanisms of the defining event in fertilization, gamete fusion, remain poorly understood. The FUS1 gene in the unicellular, biflagellated green alga Chlamydomonas is one of the few sex-specific eukaryotic genes shown by genetic analysis to be essential for gamete fusion during fertilization. In Chlamydomonas, adhesion and fusion of the plasma membranes of activated mt+ and mt- gametes is accomplished via specialized fusion organelles called mating structures. Herein, we identify the endogenous Fus1 protein, test the idea that Fus1 is at the site of fusion, and identify the step in fusion that requires Fus1. Our results show that Fus1 is a ∼95-kDa protein present on the external surface of both unactivated and activated mt+ gametes. Bioassays indicate that adhesion between mating type plus and mating type minus fusion organelles requires Fus1 and that Fus1 is functional only after gamete activation. Finally, immunofluorescence demonstrates that the Fus1 protein is present as an apical patch on unactivated gametes and redistributes during gamete activation over the entire surface of the microvillous-like activated plus mating structure, the fertilization tubule. Thus, Fus1 is present on mt+ gametes at the site of cell-cell fusion and essential for an early step in the fusion process.
UR - http://www.scopus.com/inward/record.url?scp=0038508866&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0038508866&partnerID=8YFLogxK
U2 - 10.1091/mbc.E02-12-0790
DO - 10.1091/mbc.E02-12-0790
M3 - Article
VL - 14
SP - 2530
EP - 2542
JO - Molecular Biology of the Cell
JF - Molecular Biology of the Cell
SN - 1059-1524
IS - 6
ER -