Fss1, a CTNS/PQ domain protein, has dual roles in promoting fertility in Schizosaccharomyces pombe
- 1Stowers Institute for Medical Research
Abstract
Sexual reproduction is critical in most eukaryotes, but many genes required for the process remain to be identified and characterized. A previous saturation mutagenesis study in Schizosaccharomyces pombe implicated several unnamed genes in having roles in sexual reproduction. In this work, we provide an initial characterization of 13 of these genes and an in-depth characterization of one gene, fss1 (facilitates starvation sex). Fss1 has high structural homology to the human PQ-loop repeat family PQLC2 transceptor (amino acid transporter plus membrane receptor), but likely lacks the ability to transport amino acids due to loss of a critical PQ motif. fss1{Delta} mutants have no defects in meiosis but have pronounced defects in packaging the products of meiosis into spores, particularly in nutrient-poor environments. The spore formation phenotypes are recessive as fss1{Delta} spores produced by a fss1+/fss1{Delta} heterozygote develop normally. Immuno-gold electron microscopy shows Fss1 localizes to vesicles that fuse to the ephemeral outer spore membrane as the spore wall matures below. Fss1 protein is also produced within spores and this population is required for normal vacuole morphology and timely germination. We propose a model in which Fss1 is a vesicle receptor that facilitates spore wall formation from diploid-expressed protein, while spore-expressed protein acts at the vacuole to promote an internal cellular environment that facilitates germination. This work expands our catalog of genes that contribute to sexual reproduction and identifies two previously unknown tasks in spore biology that are both facilitated by Fss1.
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BibTeX
@misc{bestul2026fss1,
title = {{Fss1, a CTNS/PQ domain protein, has dual roles in promoting fertility in Schizosaccharomyces pombe}},
author = {A. J. Bestul and J. J. Lange and S. H. Noworarski and W. B. Redwine and S. E. Zanders},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.26.761791},
url = {https://www.biorxiv.org/content/10.64898/2026.10.26.761791v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Fss1, a CTNS/PQ domain protein, has dual roles in promoting fertility in Schizosaccharomyces pombe
AU - A. J. Bestul
AU - J. J. Lange
AU - S. H. Noworarski
AU - W. B. Redwine
AU - S. E. Zanders
PY - 2026
DA - 2026/10/26
PB - bioRxiv
DO - 10.64898/2026.10.26.761791
UR - https://www.biorxiv.org/content/10.64898/2026.10.26.761791v1
AB - Sexual reproduction is critical in most eukaryotes, but many genes required for the process remain to be identified and characterized. A previous saturation mutagenesis study in Schizosaccharomyces pombe implicated several unnamed genes in having roles in sexual reproduction. In this work, we provide an initial characterization of 13 of these genes and an in-depth characterization of one gene, fss1 (facilitates starvation sex). Fss1 has high structural homology to the human PQ-loop repeat family PQLC2 transceptor (amino acid transporter plus membrane receptor), but likely lacks the ability to transport amino acids due to loss of a critical PQ motif. fss1{Delta} mutants have no defects in meiosis but have pronounced defects in packaging the products of meiosis into spores, particularly in nutrient-poor environments. The spore formation phenotypes are recessive as fss1{Delta} spores produced by a fss1+/fss1{Delta} heterozygote develop normally. Immuno-gold electron microscopy shows Fss1 localizes to vesicles that fuse to the ephemeral outer spore membrane as the spore wall matures below. Fss1 protein is also produced within spores and this population is required for normal vacuole morphology and timely germination. We propose a model in which Fss1 is a vesicle receptor that facilitates spore wall formation from diploid-expressed protein, while spore-expressed protein acts at the vacuole to promote an internal cellular environment that facilitates germination. This work expands our catalog of genes that contribute to sexual reproduction and identifies two previously unknown tasks in spore biology that are both facilitated by Fss1.
ER -