Septins localize to microtubules during nutritional limitation in Saccharomyces cerevisiae.
BACKGROUND
In Saccharomyces cerevisiae, nutrient limitation stimulates diploid cells to undergo DNA replication and meiosis, followed by the formation of four haploid spores. Septins are a family of proteins that assemble a ring structure at the mother-daughter neck during vegetative growth, where they control cytokinesis. In sporulating cells, the septin ring disassembles and septins relocalize to the prospore membrane.


RESULTS
Here, we demonstrate that nutrient limitation triggers a change in the localization of at least two vegetative septins (Cdc10 and Cdc11) from the bud neck to the microtubules. The association of Cdc10 and Cdc11 with microtubules persists into meiosis, and they are found associated with the meiotic spindle until the end of meiosis II. In addition, the meiosis-specific septin Spr28 displays similar behavior, suggesting that this is a common feature of septins. Septin association to microtubules is a consequence of the nutrient limitation signal, since it is also observed when haploid cells are incubated in sporulation medium and when haploid or diploid cells are grown in medium containing non-fermentable carbon sources. Moreover, during meiosis II, when the nascent prospore membrane is formed, septins moved from the microtubules to this membrane. Proper organization of the septins on the membrane requires the sporulation-specific septins Spr3 and Spr28.


CONCLUSIONS
Nutrient limitation in S. cerevisiae triggers the sporulation process, but it also induces the disassembly of the septin bud neck ring and relocalization of the septin subunits to the nucleus. Septins remain associated with microtubules during the meiotic divisions and later, during spore morphogenesis, they are detected associated to the nascent prospore membranes surrounding each nuclear lobe. Septin association to microtubules also occurs during growth in non-fermentable carbon sources.
Pablo-Hernando
M Evangelina
ME
Instituto de Microbiología Bioquímica, Departamento de Microbiología y Genética, CSIC/Universidad de Salamanca, 37007, Salamanca, Spain. pablo.eva@inia.es
Arnaiz-Pita
Yolanda
Y
Tachikawa
Hiroyuki
H
del Rey
Francisco
F
Neiman
Aaron M
AM
Vázquez de Aldana
Carlos R
CR
D000818:Animals; D018797:Cell Cycle Proteins / Q000032:analysis / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000032:analysis / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000032:analysis / Q000378:metabolism; D008540:Meiosis; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000378:metabolism; D013172:Spores, Fungal / Q000378:metabolism
C099502:CDC11 protein, S cerevisiae; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C512892:CDC10 protein, S cerevisiae; D020558:GTP Phosphohydrolases